What is biosurveillance? |

Definition

Biosurveillance is a systematic process of surveying the environment for viruses, bacteria, fungi, and other pathogens to detect disease in humans, animals, and plants. The process also characterizes outbreaks of such disease.

Overview

Biosurveillance combines disease surveillance with public health surveillance,
both of which depend upon data collection and analysis with the goal of early
disease detection to thwart a potential outbreak. Diseases may be defined by
incubation and infectious periods, source, and transmission route, while outbreak
characterization uses general analytic techniques, such as spatiotemporal
distribution, incidence, mortality, and cohort or case-control studies.
Biosurveillance proceeds from continuous data collection to confirmation of cases
with a feedback loop back to data aggregation. Environmental investigations
include food chains, vectors, weather, geography, the number of people who became
ill, and those at risk.

In the United States, the major use of biosurveillance is to track emerging and
reemerging infectious diseases such as H1N1 influenza, food-borne diseases
caused by resistant strains of Escherichia coli and
Salmonella, sexually transmitted diseases (STDs),
and human
immunodeficiency virus infection, which may also be
transmitted by contaminated blood products or through maternal transmission.

In the United States, government agencies conduct biosurveillance at the levels
of state and local health departments, which then report to federal agencies such
as the Centers
for Disease Control and Prevention (CDC), a division of the Department of Health and Human Services
(HHS). The CDC is responsible for collecting, analyzing, and distributing national
disease occurrence and mortality rates to state and local health authorities and
to the public. Other federal agencies conducting biosurveillance include the
Department of Defense (DoD), the Department of Homeland Security (DHS), and, globally, U.S. collaborative partners such as the
World Health
Organization (WHO), the Pan American Health Organization (PAHO), and the South East Asia Regional Office (SEARO).

Before 2000, biosurveillance systems included the National Electronic
Telecommunications System for Surveillance (NTESS) and PulseNet, the national
subtyping network comprising state and local public health laboratories and
federal food regulatory laboratories that perform molecular surveillance of
food-borne infections. Systems in place after 2000 include BioSense and other
early warning systems, such as the Real-time Outbreak and Disease Surveillance
System (RODS).

Numerous decision-making tools, such as Bayesian
inference, may be applied to the detection of an outbreak of
infectious disease. The importance of the decision-making process cannot be
overestimated when providing alerts to the public. The costs versus benefits of
false alerts must be weighed against the goal of protecting the population at
risk.

Influenza Surveillance

The CDC maintains a comprehensive surveillance system for influenza
viruses, which mutate from year to year, requiring the collection and
characterization of varying types of pathogens. Flu vaccines have to be annually
updated in accordance with surveillance data to include relevant strains.
Treatment for influenza is determined by laboratory surveillance for antiviral
resistance. The impact of influenza on hospitalizations and mortality must also be
assessed.

The epidemiology and prevention branch of the influenza division at the CDC collects and analyzes information on influenza activity throughout the year in the United States. This surveillance results in “FluView,” a weekly report, which is issued from October through mid-May of each year. The influenza surveillance system is a collaborative effort between the CDC and its many partners in state, local, and territorial health departments; public health and clinical laboratories; health care providers; clinics; and emergency departments.

The CDC employs five categories of influenza surveillance: viral, outpatient influenza-like illness (ILI), mortality, hospitalization, and Flu-SurvNET. ILI is defined as a fever (100° Fahrenheit or 37.8° Celsius or greater) and a cough or sore throat (or both) in the absence of a known cause other than influenza. Flu-SurvNET provides population-based, laboratory-confirmed estimates of influenza-related hospitalizations. Each week, approximately eighteen hundred outpatient care sites around the United States provide data to the CDC. This data includes the total number of patients with ILI, according to age group. The data by age had confirmed, for example, that young people were more adversely affected by H1N1 influenza in 2009, relative to those age sixty-five years and older (when compared with seasonal flu).

Also included in national data are human infections with novel influenza A viruses, pneumonia, influenza mortality from the 122 Cities Mortality System, influenza-associated pediatric deaths, and Aggregate Hospitalizations and Death Reporting Activity. The Emerging Infections Program (EIP) is a population-based network of the CDC and state health departments that assesses the public health impact of emerging infections and examines ways to prevent and control these infections.

Viral Surveillance

Approximately eighty U.S. and WHO collaborating laboratories and sixty labs from the National Respiratory and Enteric Virus Surveillance System (NREVSS) participate in influenza surveillance. The U.S.-WHO and NREVSS collaborating labs report to the CDC the total number of respiratory specimens tested and the number of positives for influenza types A and B each week. Reports from both U.S.-WHO and NREVSS are combined and presented in “FluView.”

Routine seasonal surveillance does not count individual flu cases, hospitalizations, or deaths (except for pediatric influenza deaths); rather, it monitors flu activity levels, trends, and viral characteristics through a nationwide surveillance system. The reporting of hospitalizations and deaths by state health departments was initiated at the start of the pandemic H1N1 outbreak in 2009. To avoid the underestimation of cases, the CDC altered this system and asked states to report both laboratory confirmed hospitalizations and deaths and presumed influenza or pneumonia deaths on cases coded as ICD-9 (International Classification of Diseases). The CDC also created a Web-based data application for states to submit their numbers each week. This data is compiled for publication in the CDC’s Morbidity and Mortality Weekly Report (MMWR) and in “FluView.”

HIV and AIDS Surveillance

The annual HIV Surveillance Report
provides an overview of the most up-to-date epidemiology data on HIV infection in the United States and five U.S. territories. The CDC funds state and territorial health departments so they can collect data on persons with HIV infection; all personal identifiers are removed before data is transmitted to the CDC through a secure data network. Data are analyzed by the CDC and then displayed by age, race and ethnicity, gender, and transmission category, a significant change in the operation of the surveillance system. Moreover, the HIV Surveillance Report for 2012 (to be issued in 2014) marks the first time that data is included from each of the fifty states.

In 2008, changes were made to the case definition of HIV infection. To
accurately track the epidemic, emphasis is now be placed on HIV surveillance
rather than on acquired immunodeficiency disease syndrome (AIDS)
surveillance. HIV testing and linkage to care are essential for identifying
persons early.

Approximately 1.1 million persons in the United States are HIV-positive. The CDC used 2001 to 2009 data from the National Health Interview Survey to estimate percentages of persons age eighteen through sixty-four years who reported being tested (at any time) for HIV in the United States. Data from the national HIV surveillance system were employed to estimate cases and rates of HIV infection, AIDS diagnoses, and late diagnoses of HIV infection. In turn, these data were used to determine the populations and regions most affected by HIV and AIDS and to determine the trends in HIV testing and late diagnoses.

Food-borne Disease Outbreak Surveillance

Food-borne pathogens cause an estimated seventy-six million illnesses annually in the United States. Data from outbreak surveillance provides insights into the etiology of these illnesses, the foods in question, and their settings. State, local, and territorial health departments use a standard, Web-based form to report food-borne outbreaks to the Foodborne Disease Outbreak Surveillance System.

As reported to the CDC, 1,097 food-borne outbreaks occurred in 2007, which
resulted in 21,244 cases of illness and 18 deaths; of the single, laboratory
confirmed agents of outbreak-associated illnesses, 12,767 were caused by norovirus
(47 percent) and Salmonella (27 percent). In July, 2010, the CDC
collaborated with public health officials in several states and with the HHS, FDA,
and the Department of Agriculture (USDA) Food Safety and Inspection
Service to investigate a nationwide rise in S. enteritidis (SE)
infections. Investigators used deoxyribonucleic acid (DNA) analysis of SE bacteria
obtained through diagnostic testing to identify cases of illness. They also
identified restaurant and event clusters that may have been associated with this
outbreak. Investigators determined that eggs contaminated by
Salmonella were responsible for the outbreak. In late
November, 2010, following a recall and ban, the FDA issued permits to some of the
affected farms, allowing the resumption of egg sales.

Impact on Global Public Health

The age of public health globalization has arrived. Global health and global
health surveillance have come to the fore, in part because of newly emerging and
reemerging infectious diseases. In addition, climate change, poor hygiene and
sanitation, lack of economic and food security, political unrest, war, and
accelerating threats of bioterrorism have greatly increased global morbidity and mortality from
infectious diseases, especially in developing countries.

To counter these challenges, global health surveillance procedures have been updated. Changes were made to the new International Health Regulations (IHR), new global networks were developed, and specific guidelines to monitor emerging diseases and acts of bioterrorism were developed. Global surveillance now provides real-time information about potential outbreaks and epidemics.

Global response to the 2009 H1N1 influenza pandemic demonstrated the benefits of the new global monitoring systems and the importance of WHO in coordinating the global public-health community. As a result, valuable models were developed on how to respond to novel strains of influenza and other pathogenic entities, such as the severe acute respiratory syndrome (SARS) virus. As the number of cases H1N1 influenza cases increased and rapidly spread, it was apparent that significant resources, intervention, and biosurveillance at the international level would be necessary.

Bibliography

Burkle, F. M., Jr, and P. G. Greenough. “Impact of Public Health Emergencies on Modern Disaster Taxonomy, Planning, and Response.” Disaster Medicine and Public Health Preparedness 2 (2008): 192-199. Examines disaster taxonomy and how it defines variability, unique characteristics, and classification of disasters. Also looks at how compromised publichealth infrastructure and systems may impact public health consequences, especially those that are “widespread, population dense, and prolonged.”

DeFraites, Robert F., and William C. Chambers. “Gaining Experience with Military Medical Situational Awareness and Geographic Information Systems in a Simulated Influenza Epidemic.” Military Medicine 172 (2007): 1071-1076. Examines the practice of medical situational awareness in integrating relevant medical and operational information to bolster decision making.

Giles-Vernick, Tamara, and Susan Craddock, eds. Influenza and Public Health: Learning from Past Pandemics. London: Earthscan, 2010. Discusses from a historical perspective the lessons learned from past flu pandemics about transmission patterns and successful (and not so successful) interventions.

Lazarus, R., et al. “Using Automated Medical Records for Rapid Identification of Illness Syndromes (Syndromic Surveillance): The Example of Lower Respiratory Infection.” BMC Public Health 1 (2001): 9. Discusses how information gleaned from automated medical records complements current surveillance programs by evaluating most episodes of illness for which no etiologic agent is defined.

Lober, W. B., L. Trigg, and B. Karras. “Information System Architectures for Syndromic Surveillance.” Morbidity and Mortality Weekly Report 5, suppl. (2004): 203-208. Describes the information-architecture components of a particular surveillance data system.Discusses existing and potential approaches to data integration.

O’Neil, Eileen A., and Elena N. Naumova. “Defining Outbreak: Breaking Out of Confusion.” Journal of Public Health Policy 28 (2007): 442-455. Illustrates the complexity of defining terms used to describe emerging and reemerging infectious diseases that have resulted in the use of emotionally charged terms such as “outbreak.” Argues that public health may benefit from strengthening the definitions of key terms.

What is a heart valve replacement?

Indications and Procedures

Valve replacement surgery is a procedure used when a heart
valve no longer functions properly. There are several reasons that a heart valve may fail. Sometimes, a major defect present at birth must be repaired immediately. Minor defects present at birth may go undetected for years. When and if these minor defects become worse as a result of aging, valve replacement surgery may be necessary. Another cause of heart valve damage is infection. Rheumatic fever
can cause the scarring of a valve. These scars can become more of a problem with age, and surgery may eventually be necessary. Bacterial endocarditis
is another type of infection that can damage the heart very quickly. Valve replacement surgery is often needed as a result of this type of infection.

When a heart valve is damaged, the result is usually stenosis or regurgitation. Stenosis
occurs when the valve becomes thick and hard. As a result, normal blood flow through the valve is obstructed. A valve that becomes stretched or weak may not close properly, resulting in blood flowing backward through the valve; this is called regurgitation. When the blood flows through an abnormal valve, turbulence occurs and a sound is made. This sound, called a murmur, generally can be heard with a stethoscope.

When a heart valve fails to function properly, the ability of the heart to do work is impaired. In an attempt to maintain normal work levels, the heart begins to enlarge, or experience hypertrophy
. When further hypertrophy is no longer possible, the heart fails. This condition will result in permanent damage to the heart muscle and eventually death. Some of the symptoms of valve problems include chest pain or tightness, shortness of breath, temporary blindness, slurred speech, weakness, numbness, lack of coordination, unusually rapid weight gain, fatigue, and loss of consciousness. These symptoms are typically the result of inadequate blood flow, particularly to the brain.

In some cases, surgery can be used to repair the valve. Many times, however, the damage is too extensive for this type of surgery, and the valve must be replaced. The replacement valve may come from a deceased person’s heart or from an animal’s heart (usually that of a pig), or it may be a mechanical (prosthetic) valve. Prosthetic valves are made from metal, plastic, or carbon ceramic.

During valve replacement surgery, the chest is opened to expose the heart. Blood flow through the heart is diverted through an oxygenator and a pump that maintains the flow of oxygenated blood throughout the body. The surgeon removes the damaged valve and sutures a replacement valve to the heart. Upon completion of the surgery, if the replaced valve functions effectively, normal blood flow is restored through the heart.

Uses and Complications

Heart valve replacement is a very reliable procedure. Although problems with the new valve are possible, the majority of these surgeries are quite effective. Nevertheless, there are two long-term concerns for the patient. Blood thinners or anticoagulants—drugs that slow the clotting process and may prevent blood clots—are usually required with prosthetic valves. These drugs help prevent blood from coagulating in and around the new valve. Some patients must also take antibiotics to prevent additional infections in the heart. Antibiotics are needed especially when patients visit the dentist, when bleeding is likely. If bleeding occurs, bacteria may enter the blood and become lodged in the replacement valve. The ensuing infection can cause further damage to the heart.

When one compares the use of tissue versus mechanical (prosthetic) valves for replacement, some differences emerge. In general, tissue valves work better. In addition, they are less likely to require drugs to increase blood-clotting time. On the other hand, they are harder to obtain. With more people acting as donors and with better preservation techniques becoming available, tissue replacements are preferred.

Perspective and Prospects

Mechanical valves were first used as replacements for damaged valves in the early 1960s. In 1962, the initial clinical use of tissue valves was described. Tissue valve replacements were conducted simultaneously by Donald Ross in England and Sir Brian Barratt-Boyes in New Zealand. The acceptance of tissue valve use was slow because the number of donors was small and the methods for preserving valves for later use were poor. The result was shorter survival times for the replacement valves used in the 1960s and early 1970s.

By the 1980s, better preservation techniques were developed, which allowed surgeons to use living human tissue. These replacements have been found to be superior to nonliving tissues and mechanical valves. In the future, both mechanical and tissue replacements will continue to be used, based on availability and the specific needs of the patient. Newer, less invasive surgical approaches are being investigated in clinical trials.

Bibliography

Alpert, Joseph S., James E. Dalen, and Shahbudin H. Rahimtoola, eds. Valvular Heart Disease. 3d ed. Philadelphia: Lippincott Williams & Wilkins, 2000.

Altunkaya, Sabri, Sadik Kara, Niyazi Görmüş, and Saadetdin Herdem. "Comparison of First and Second Heart Sounds after Mechanical Heart Valve Replacement." Computer Methods in Biomechanics & Biomedical Engineering 16, no. 4 (April 2013): 368–380.

Bonhoeffer, Philipp, et al. “Percutaneous Replacement of Pulmonary Valve in a Right-Ventricle to Pulmonary-Artery Prosthetic Conduit with Valve Dysfunction.” The Lancet 356, no. 9239 (October 21, 2000): 1403–1405.

"Choosing the Right Replacement Heart Valve." Harvard Heart Letter 21, no. 2 (October 2010): 4–5.

Crawford, Michael, ed. Current Diagnosis and Treatment—Cardiology. 3d ed. New York: McGraw-Hill Medical, 2009.

Eagle, Kim A., and Ragavendra R. Baliga, eds. Practical Cardiology: Evaluation and Treatment of Common Cardiovascular Disorders. 2d ed. Philadelphia: Lippincott Williams & Wilkins, 2008.

"Heart Valve Replacement." Health Library, May 8, 2013.

Kramer, Gerri Freid, and Shari Mauer. Parent’s Guide to Children’s Congenital Heart Defects: What They Are, How to Treat Them, How to Cope with Them. New York: Three Rivers Press, 2001.

Mitka, Mike. “Final Report on Mechanical vs. Bioprosthetic Heart Valves.” Journal of the American Medical Association 283, no. 15 (April 19, 2000): 1947–1948.

Nauer, Kathleen A., Barbara Schouchoff, and Kathleen Demitras. “Minimally Invasive Aortic Valve Surgery.” Critical Care Nursing Quarterly 23, no. 1 (May, 2000): 66–71.

Otto, Catherine M. “Timing of Aortic Valve Surgery.” Heart 84, no. 2 (August, 2000): 211.

What are vaccine types? |

Definition

A vaccine is a suspension of immunogens (molecules that produce an immune
response or stimulate production of antibodies) such as weakened or dead
pathogenic (disease-causing) cells or cellular components. The act of
administering a vaccine, or immunization, is called vaccination. Persons who
receive a vaccine are considered immunized against a particular pathogen.
Vaccines may contain a pathogen, suspending fluid, adjuvants, excipients, and preservatives.

Several types of vaccines are given to humans. These types include live attenuated, inactivated, component or subunit, toxoid, conjugate, deoxyribonucleic acid (DNA), and recombinant vector vaccines. Live attenuated vaccines contain living but altered bacteria or viruses that do not cause disease. Inactivated or killed vaccines contain killed bacteria or inactivated viruses that do not cause disease. Component or subunit vaccines contain parts of the whole bacteria or viruses. Toxoid vaccines contain toxins (or poisons) produced by the pathogen that have been made harmless. Conjugate vaccines allow the immune system to recognize certain bacteria disguised by a polysaccharide outer coating and therefore respond. DNA and recombinant vector vaccines are in the experimental stage and both use genetic material to stimulate an antibody response.

Some vaccines are combinations of pathogens for different diseases, such as that for measles, mumps, and rubella (or MMR vaccine). Most vaccines are administered by injection into the muscle (intramuscular); however, some may be given into the skin (subcutaneous), by mouth, or into the nose (intranasal).

Active immunity is classified as natural (after pathogen exposure and
infection) or acquired (after vaccination). Passive immunity is also classified as natural (across the placenta
during pregnancy) or acquired (injection of antibodies or immunoglobulins pooled
from several donors). Immunoglobulins are prepared antibodies that are given to a
person who has already been infected or who is at risk of acquiring an infection,
thereby providing passive immunization. In this case, the immune system
does not need to produce antibodies protecting the body.

Herd immunity occurs when most of, but not all, the people in a given population are immune to a pathogen. If there is an outbreak or exposure to a pathogen, those who are immune will sometimes naturally protect those who are not immune from getting the disease; however, those who are not immune are still more likely to get the disease and spread it to others.

Mechanisms of Action

A vaccine is given to intentionally expose the immune system to a pathogen in a safe, controlled manner, so that the
immune system can react and develop antibodies to that pathogen or
antigen. Antibodies are large proteins that help fight infection and control
disease. Many antibodies disappear after destroying the invading antigens, but the
cells involved in antibody production remain and become memory cells. Memory cells “remember” the original antigen and then
defend against it if the antigen attempts to reinfect a person. This protection is
called immunity. Therefore, after sufficient antibodies have been developed,
the immune system that is re-exposed to that pathogen will react within minutes to
hours; the pathogen will be destroyed before a full-fledged infection and organ
damage can occur. B cells are a type of lymphocyte (white blood
cell) that makes antibodies. B cells use antibodies to
identify, inactivate, and help destroy these pathogens.

Vaccines, which provide protection from the disease without the serious symptoms, have a high effectiveness rate (usually 95 to 99 percent). Vaccine failure, meaning that the vaccine administration did not result in antibody production, is uncommon. Several factors can lead to vaccine failure, including having an already compromised immune system and the inadequate storage or administration of the vaccine. The immune response to a pathogen may decrease over time, so vaccines known as boosters are sometimes given to restore antibodies. Protective immunity lasts longer with boosters.

A suspending fluid (such as sterile water or saline) is needed to allow the
vaccine to be administered. Preservatives and stabilizers, such as albumin,
phenols, and glycine, keep the vaccine from being changed. Adjuvants, or
enhancers, help the vaccine work. Adjuvants help promote an earlier, more potent
response and a more persistent immune response to the vaccine. Antibiotics
prevent the growth of bacteria during production and storage of the vaccine. Eggs
are used to grow the pathogen, and egg protein is found in influenza and
yellow fever
vaccines. Formaldehyde is used to inactivate bacterial
products for toxoid vaccines and to kill unwanted viruses and bacteria that might
contaminate the vaccine during production. Monosodium glutamate and
2-phenoxy-ethanol are preservatives that help the vaccine remain unchanged during
the vaccine’s exposure to heat, light, acidity, or humidity. Thimerosal is a
mercury-containing preservative that helps prevent contamination and growth of
bacteria.

Most vaccines are given to prevent disease and are effective only if
administered to the person before he or she is exposed to the pathogen or disease;
most vaccines must be given by a certain age to ensure effectiveness. Also, most
vaccine-preventable diseases can cause serious or life-threatening infections in
infants and young children. For example, exposure and infection with
polio can occur at a very young age and can cause paralysis,
so the vaccine should be given to infants as soon as possible. Immunity to some
pathogens can be transferred from a pregnant woman to her fetus, but this immunity
wanes once the newborn is older than six months of age. Breast feeding can also
help extend immunity to some diseases, but even this is limited.

Certain vaccines (such as pneumococcal or hepatitis B vaccines) are given once in a lifetime, unless a booster is needed. The seasonal influenza vaccine, however, is given annually because hundreds of influenza-like viruses exist; also, the seasonal variations or types of virus that are prevalent change every year. Vaccination schedules have been developed for children, adolescents, and adults that indicate when these persons should receive doses of required vaccinations or boosters.

Vaccine Types

The selection of the type of vaccine depends on fundamental information or factors about the pathogen. These factors include how the pathogen infects cells and how the immune system responds to it. Practical considerations include the regions of the world where the vaccine would be used. Pros and cons are associated with each type of vaccine.

Live attenuated vaccines. Live attenuated vaccines are usually created from the naturally occurring pathogen. The pathogen’s ability to cause serious infection is attenuated, or weakened, by manipulating the virus or bacteria in a laboratory environment, but these vaccines can still induce antibody production or a protective immune response. Attenuation of the pathogen usually is done by “passing” or growing the virus or bacteria from culture to culture before it is formulated into a vaccine. Live attenuated vaccines elicit strong cellular and antibody responses and often confer lifelong immunity with only one or two doses. Not everyone can safely receive live attenuated vaccines, however. People with weakened immune systems cannot be given live vaccines because of the risk they will develop disease symptoms.

These types of vaccines usually need to be refrigerated to stay potent. Proper storage then becomes critical in maintaining vaccine efficacy. Examples of live attenuated vaccines include measles, mumps, and rubella (MMR vaccine), oral polio vaccine (OPV), the nasal form of the influenza (flu) vaccine, and the varicella vaccine (chickenpox vaccine).

Inactivated vaccines. Inactivated vaccines contain a killed pathogen that cannot cause the disease but can stimulate antibody production. Pathogens can be inactivated with chemicals such as formaldehyde. Inactivated vaccines are more stable and safer than live vaccines. These vaccines usually do not require refrigeration and are easily stored and transported in freeze-dried form, making them useful in situations requiring long transportation or with less-developed medical infrastructure. Most inactivated vaccines, however, produce a weaker immune response than do live vaccines. Several additional doses or booster shots, therefore, are needed to maintain immunity. Examples of inactivated vaccines include inactivated polio vaccine (IPV) and inactivated (injectable form) influenza vaccine.

Component or subunit vaccines. Component or subunit
vaccines are made by using only parts of the pathogen. These vaccines
cannot cause disease, but they can stimulate the body to produce an immune
response against the disease. Component vaccines contain only the essential
antigens, but not all the other molecules, of the pathogen, so the chance of an
adverse reaction to the vaccine is lessened.

These vaccines can contain anywhere from one to twenty or more antigens.
Identifying what antigens best stimulate the immune system can be a tricky,
time-consuming process. A recombinant component vaccine has been created for the
hepatitis
B virus. Hepatitis B genes that code for important antigens
were inserted into common baker’s yeast. The yeast then produced the antigens,
which were collected and purified for use in the vaccine.

A conjugate vaccine is another type of component vaccine that has been developed for bacterium that possesses an outer coating of sugar molecules called polysaccharides. The polysaccharide coating disguises the internal antigens of the bacterium so that the immune system does not recognize or respond to it. Vaccines help the immune system link the polysaccharide coating to the bacterium and, therefore, allow antibodies to produce immunity to that pathogen. Examples of component vaccines include Haemophilus influenzae type B (Hib) vaccine, hepatitis B (Hep B) vaccine, hepatitis A (Hep A) vaccine, and pneumococcal conjugate vaccine.

Toxoid vaccines. Toxoid
vaccines are made by treating the toxin produced by the pathogen with
heat or chemicals, such as formalin (a solution of formaldehyde and sterilized
water). For pathogens that secrete toxins or harmful chemicals, a toxoid vaccine
may be used when the toxoid is the main cause of illness. Toxins are inactivated
and do not produce disease. Detoxified toxins are called toxoids. After
vaccination with a toxoid vaccine, the immune system produces antibodies that
block the toxin. Examples of toxoid vaccines include those against
diphtheria and tetanus.

DNA vaccines. DNA
vaccines, which are experimental, contain the genes that code for antigens. This requires that the genes from the pathogen be analyzed. DNA vaccines would stimulate an immune response to the free-floating antigen secreted by cells and would stimulate a response against the antigens displayed on cell surfaces. DNA vaccines would contain copies of a few of the pathogen’s genes, so the vaccine would not cause disease.

DNA vaccines are relatively easy and inexpensive to design and produce. Naked DNA vaccines, which consist of DNA that is administered directly into the body, could be mixed with molecules that facilitate its uptake by the body’s cells. Naked DNA vaccines for influenza and herpesviruses are being investigated.

Recombinant vector vaccines. Recombinant vector vaccines, also experimental, use an attenuated pathogen to introduce DNA to cells of the body. A vector in this case is a harmless virus or bacterium used as a carrier. Certain harmless or attenuated viruses are used to carry portions of the genetic material from other microbes. The carrier viruses then ferry the microbial DNA to cells and display the antigens of the pathogen on the cell’s surface. The harmless organism mimics a pathogen and provokes an immune response. Recombinant vector vaccines closely mimic a natural infection, effectively stimulating the immune system. Recombinant vector vaccines for human immunodeficiency virus (HIV), rabies, and measles are under investigation.

Controversy

State laws in the United States mandate that children in day care and students
be immunized against certain diseases. Some exceptions are allowed. Still, many
parents are refusing to immunize their children for fear of a link between
autism, for example, and the use of vaccines containing thimerosal, a mercury-based preservative. Although scientific
evidence does not support this link, thimerosal is no longer used in the
production of most vaccines in the United States. To alert persons to adverse
effects associated with vaccine administration, and to educate parents and others
about what to expect after receiving a vaccine, an information sheet must be given
to each person before he or she can be vaccinated.

Impact

Disease prevention is the key to public health, and it is always better to prevent a disease than to have to treat it. Vaccination is considered one of the most important medical discoveries in all of human history. Diseases can cause suffering, permanent disability, and death. Vaccines prevent disease in those who get vaccinated and protect those who come into contact with unvaccinated persons. Vaccination has controlled many infectious diseases that were once common, including polio, measles, diphtheria, pertussis (whooping cough), rubella (German measles), mumps, tetanus, and influenza. It even led to the complete eradication of smallpox from the human population.

Not all countries have the same level of vaccination requirements as the United States. Given the current global nature of travel and business, exposure to many diseases is likely. Vaccination minimizes the risk of developing a disease and its associated complications. When persons travel outside the United States, additional vaccinations may be needed. One should consult a physician within a minimum of four weeks of traveling to determine what vaccines, if any, are needed.

Bibliography

Centers for Disease Control and Prevention. “General Recommendations on Immunization: Recommendations of the Advisory Committee on Immunization Practices.” Morbidity and Mortality Weekly Report 55 (December 1, 2006): 1-48. Print.

Centers for Disease Control and Prevention. “Immunization Schedules.” Available at http://www.cdc.gov/vaccines/recs/schedules.

Centers for Disease Control and Prevention. “Understanding the Basics: General Recommendations on Immunization.” Available at http://www2a.cdc.gov/nip/isd/ycts/mod1/courses/genrec/10300.asp.

Merino, Noël. Vaccines. Farmington Hills: Greenhaven, 2015. Print.

Plotkin, Stanley A., Walter A. Orenstein, and Paul A. Offit. Vaccines. 5th ed. Philadelphia: Saunders/Elsevier, 2008. Print.

Shoenfeld, Yehuda, and Nancy Agmon-Levin. Vaccines and Autoimmunity. Hoboken: Wiley, 2015.

"Types of Vaccines." National Institute of Allergy and Infectious Disease. National Institutes of Health, 3 Apr. 2012. Web. 31 Dec. 2015.

How can being a white female matter in how you read "Theme for English B" by Langston Hughes, or does it matter at all? Do you think these...

This is such an interesting question!  I do not want to hedge in my answer, but there are ways in which it does matter and ways it does not matter.  I will certainly explain that as I go along. The keys to understanding the poem are in the audience and in the use of the second person.   

What I asked myself first as I decided to respond to this question is to whom is Hughes addressing his poem.  As a matter of common sense, he surely anticipates a readership well beyond one older English teacher, so on one level, it does not matter at all.  He is not really "talking" to this person.  But on another level, it matters a great deal.  It is quite likely that he did have a white English teacher, and he may very well have been the only student of color in the classroom.  This is the person he has in his mind as he writes his "truth."  And this person is a symbol of what may not be exactly racism, but of the larger world that has no insight into young people who are "other." 

As someone who has been that white, older English teacher, certainly, I understand the poem in a way that is different from someone who has not been in that position. For example, there is the slight mocking of the teacher's advice,

Go home and write
a page tonight.
And let that page come out of you---
Then, it will be true (lines 2-5).

English teachers are prone to giving advice like this or saying things like "Write what you know."  These are not always the most helpful of instructions for students.  And as someone white and far older than the African-American students I have had in class, Hughes also needs this teacher as his foil, so to speak, to make the point that "truth" is likely to be quite different for him from the truth of his teacher, as he says,

It's not easy to know what is true for you or me
at twenty-two, my age...(lines 16-17).

So, in addition to mocking these instructions, he is also making clear the idea that they are unlikely to have the same "truth."  

However, I can't imagine that anyone else's understanding of the poem is diminished in some way by not being a white English teacher because while on one level, Hughes is addressing that teacher, on another level, he is asking the reader to understand how it is to be a black student in a white world, with a very different kind of truth from those around him.  A white reader who is not an English teacher is fully capable of understanding this, and a black reader can often easily identity with these feelings, even today.  He is saying to the reader, "I am other," and "This is part of my truth." 

Using the second person point of view, Hughes accomplishes a great deal. First, so many students write in the second person, as though they were addressing their teacher only. This makes his poem feel like an authentic student response.  Second, using the second person point of view gives the poem some immediacy that it would lack if Hughes had written all of this information in the third person point of view, saying, for instance, "My teacher is older and white."  Finally, the use of the second person point of view provides a direct and personal relationship with the reader, a familiarity that really makes us feel he is speaking directly to us.  I think the success of the poem depends to some degree on the direct address to the teacher. 

So, you see, it matters not at all whether or not the reader is a white English teacher, puts him or herself in the shoes on a white English teacher, or simply reads the poem as a human being.  The poem works because it is on two levels, first, what feels like an authentic response from a student who is "other," and second, because every reader can gain some empathy and insight into what this feels like.  It is one of my favorites of his and always has been.  Perhaps I have a bias because of my background! 

What is cross-cultural psychology? |

Introduction

Cross-cultural psychology is a broad term for the scientific study of human behavior and mental or cognitive processes within different cultures. In general, this field addresses similarities and differences between cultures. According to the American social psychologists Richard Nisbett and Ara Norenzayan, the view that there are differences between cultures, at least in terms of cognitive processes, was not widely held in the twentieth century. Instead, most psychologists assumed that basic cognitive processes were universal—that the fundamental aspects of thinking and perceiving that involve attention, memory, learning, and reasoning operated in the same way among all cultures. Based on their research and that of other scholars, Nisbett and Norenzayan concluded that the basic processes of thinking and behavior are shaped by culture, although there are aspects of thinking and perceiving that may be innate (genetic or possessed at birth) and that limit or constrain the degree to which such shaping is possible.

How Thinking Constrains Culture

In the field of developmental psychology, there is much evidence to suggest that very young children have sets of basic building blocks that they use to understand human minds, important entities, and world events. These sets of building blocks are thought to be innate and domain specific (for example, one set helps children understand how other people think, and another set helps them understand the properties of objects). Evidently, they are common to all infants across cultures and limit the types of thinking about the world that can exist in any culture.

For example, the American developmental psychologist Elizabeth Spelke describes an experiment in which infants were shown a single toy animal placed on a stage. A curtain was lowered to hide or occlude the toy, and a second toy was shown to the infants and then placed behind the screen. Next, the screen was raised, revealing either both toys or only one of the toys. Infants looked longer at the single toy than the two toys. This finding shows that the infants were able to keep track of the two objects in their minds, even when the objects were hidden, and were surprised that one of the toys had disappeared. It also suggests that infants do not need to learn that objects do not spontaneously disappear. Related experiments by American developmental psychologist Renee Baillargeon show that without being taught, infants understand that objects cannot spontaneously appear, break apart, coalesce, or change size, shape, pattern, or color. This findings illustrate one of the basic building blocks of all cultures, the principle of persistence, which states that certain object changes are impossible.

Another type of thinking that may constrain cultures involves ideas about religion. American anthropologist and psychologist Pascal Boyer notes that religions share many similar beliefs across cultures—for example, the belief that something nonphysical, such as an invisible spirit, survives after a person’s death and can be contacted by a select few individuals. These ideas arise from basic beliefs shared among cultures about physics, biology, and the mind.

How Culture Shapes Thinking

Differences between cultures lead to different ways of thinking. Consider the differences between individualistic and collectivistic cultures. In an
individualistic culture, people view themselves more as individuals and are taught to act independently, taking personal responsibility for their successes and failures. In a collectivistic culture, people view themselves more as members of groups and are taught to act interdependently, favoring the needs of the group over their own individual needs. The United States is an example of an individualistic culture, while most East Asian cultures are collectivistic.

These different cultural perspectives affect thinking in many ways. For example, one important finding in social psychology is the fundamental attribution error, which is the tendency to overestimate how much a person’s behavior is due to dispositional factors and to underestimate how much it is due to situational factors. Dispositional factors refer to a person’s internal characteristics, such as personality traits, abilities, and motives; situational factors refer to external causes. For example, students might explain that they did well on an exam because they are intelligent (a dispositional factor) or because the teacher gave an easy exam (a situational factor). Collectivistic cultures are less likely to make the fundamental attribution error than individualistic cultures. For example, cultural psychologists Michael Morris and Kaiping Peng examined newspaper reports of two mass murders and found that an American newspaper was more likely to describe the mass murders in terms of dispositional factors, such as a very bad temper, whereas a Chinese newspaper was more likely to focus on situational factors, such as isolation from the Chinese community due to having been recently fired.

Cultures arise in different geographical regions and environments, which can lead to important differences between cultures. One area of differences is the family structure. Most families across societies have parents who are monogamous (one man married to one woman). However, in some families, there is polygamy, which includes polyandry (one woman married to more than one man) and polygyny (one man married to more than one woman). According to American social psychologists Douglas Kenrick, Steven Neuberg, and Robert Cialdini, polygamy arises in cultures because of survival needs. For example, a polyandrous woman in Tibet may marry several men who are brothers because the harsh environment in the high Himalayan desert makes it difficult for a single man and woman to survive. The brothers in turn share the wife so that they can preserve the family estate from generation to generation. This family structure, which is called fraternal polyandry, appears to be driven by economic conditions originating from the environment.

Bibliography

Berry, John W., et al. Cross-Cultural Psychology: Research and Applications. 3rd ed. Cambridge: Cambridge UP, 2011. Print.

Goldstein, Susan. Cross-Cultural Explorations: Activities in Culture and Psychology. 2nd ed. Boston: Pearson, 2008. Print.

Heine, Steven J. Cultural Psychology. 2nd ed. New York: Norton, 2012. Print.

Keith, Kenneth D., ed. Cross-Cultural Psychology: Contemporary Themes and Perspectives. Malden: Blackwell, 2011. Print.

Krumov, Krum, and Knud S. Larsen. Cross-Cultural Psychology: Why Culture Matters. Charlotte: Information Age, 2013. Print.

Laungani, Pittu D. Understanding Cross-Cultural Psychology: Eastern and Western Perspectives. Thousand Oaks: Sage, 2007. Print.

Matsumoto, David, and Fons J. R. van de Vijver, eds. Cross-Cultural Research Methods in Psychology. New York: Cambridge UP, 2011. Print.

Nisbett, Richard E. The Geography of Thought: How Asians and Westerners Think Differently . . . and Why. New York: Free, 2003. Print.

Shiraev, Eric B., and David A. Levy. Cross-Cultural Psychology: Critical Thinking and Contemporary Applications. 5th ed. Boston: Pearson, 2013. Print.

How is complementary alternative medicine regulated?

Overview

Systems of rules and guidelines comprise the legal framework enforced by institutions to regulate economics, politics, and many other aspects of modern society. While all legal systems deal with comparable basic issues, each respective country recognizes, classifies, and interprets its legal components and topics differently. Typically, the purpose of a law is to restrict and control harm to others by serving as a social mediator among the parties involved. Thus, focusing on public protection, which includes patient and health consumer safety, governments regulate affairs in the public health arena and in the care provided by health professionals.

Consumers appropriately want to have confidence in their health professionals, whether those professionals are practicing conventional Western medicine or complementary alternative medicine (CAM). When people need care, they entrust themselves to doctors, nurses, and a whole range of other trained health care professionals, including CAM practitioners. People want to know that their trust is appropriately placed and that they will not be mistreated or harmed. The preservation of trust is the foundation for the care provided. Through regulation and oversight, a framework of guidelines, rules, and controls are built into the system to maintain patient safety and efficacy of treatments, products, therapies, and practices.

CAM is a $34 billion annual industry, according the 2007 National Health Survey conducted by the Centers for Disease Control and Prevention’s National Center for Health Statistics. Most of this spending for therapies, products, office visits, classes, and relaxation techniques is not covered by health insurance in the United States. The safety and efficacy of these products and therapies are not the only pressing issues that require regulatory attention.

Despite CAM’s popularity, strong debates surround its practice because of the unclear nature of some of its therapies and because of the broad array of claims different practitioners make. Some of the ingredients and claims of natural products and practices contribute to greater controversy because of the lack of formal quality standards and clinical trials, which are normally expected by the scientific community.

Although CAM use has been rising around the world through the years, the evolution of CAM regulation has been ineffective, failing to keep up with the expansion of its use, demands, and needs. Generally, existing CAM regulatory models have either been absent or been inadequate. CAM advocates defend consumer freedom and their right to have access to healing alternatives compatible with their own values, beliefs, and philosophies toward health and life. However, government regulators are still trying to find a regulatory balance to protect consumers from negative outcomes, adulteration, or misbranding of products or therapies. At the same time, regulators are trying to avoid limiting access to holistic, nonbiomedical therapies.

Federal Legal Authority

The U.S. Food and Drug Administration (FDA) issued the “Guidance for Industry: Complementary and Alternative Medicine Products and Their Regulation by the Food and Drug Administration” (2006) in response to the increased use of CAM practices and products in the United States. This document also addresses rising public confusion about whether certain therapies or products used are subject to regulation.

“The Guidance” has two main regulatory points. First, a CAM product might be subject to regulation as a drug, a biological or cosmetic device, or a food (including food additives and dietary supplements) under the Federal Food, Drug and Cosmetic (FFDC) Act or the Public Health Service (PHS) Act. These statutory classifications cover several CAM products.

Second, neither FFDC nor PHS relieves CAM products from regulation. As the FDA receives its laws from the U.S. Congress, it has legal authority based on the legal tools Congress has given the agency. In deciding law-science issues, FDA efforts are based on sound scientific rationale related to ensuring safe therapies and products for consumers, while balancing access to the highest reasonable standard of health.

The FFDC is a federal law enacted by Congress that establishes the legal framework for how the FDA works. The FFDC is found in the United States Code (starting at 21 U.S.C. 301). The FDA develops regulations based on the laws under which it operates. The agency, guided by the Administrative Procedure Act (a federal law), follows procedures to issue its regulations. FDA regulations are also federal laws, although they are not part of the FFDC. FDA regulations are found in Title 21 of the Code of Federal Regulations. The agency adheres to procedures in its “Good Guidance Practice.” Guidelines, however, are not legally binding.

Some CAM advocates oppose any legal intervention in their affairs, considering guidances and regulations to be governmental restrictions. Regulation critics state that the FDA’s criteria for experimental evaluation methods are orthodox and that it obstructs CAM practioners attempting to bring valuable and effective treatments to the public. CAM advocates argue that their contributions and breakthroughs are often unjustly dismissed, unnoted, or stifled. CAM providers acknowledge that health fraud does occur, and they agree that it should be appropriately addressed and curtailed. However, they also argue that restrictive regulations should not spread to valid CAM health practices and products.

Standards and Science-Based Regulation

Conventional biomedical drugs obtain FDA market approval only after clinical trials establish their efficacy. Safety testing is another legal requirement. Biopharmaceutical manufacturing standards are strictly regulated to guarantee a given medicine has uniform and standard quantity, identity, purity, and strength of an active ingredient in its formulation, and that it is not contaminated or adulterated. Because alternative health products are not governed by the same quality-control standards as non-CAM products, one might see inconsistencies among doses. As result, CAM products are susceptible to contamination, adulteration, misbranding, and fraud.

Because there are no global, harmonized CAM regulatory guidelines, world commerce amplifies the problem, as each country may or may not have its own quality standards, levels of regulation, and legal authority to enforce compliance. The FDA believes that all of this puts consumers in an unfair and difficult position: how to properly evaluate the risks and qualities of natural treatments.

CAM proponents assure consumers that their healing therapies are natural, harmless, and effective. From the CAM perspective, regulations personify a dividing model within the healing arts flanked by traditional medicine and unconventional health care. Proponents argue that the law endorses and favors biomedicine. Some CAM promoters state that guidance language is confusing to the consumer and is unconstitutional. They are concerned that regulations are restricting access to natural therapies. Proponents want the FDA to better articulate the equilibrium between consumer protection and consumer freedom.

Regulation of CAM Therapies

The National Center for Complementary and Alternative Medicine (NCCAM) is part of the National Institutes of Health (NIH). The FDA’s CAM guidance expanded on the CAM categories of NCCAM for its development and issuance. The five major regulated categories are whole medical systems, mind-body medicine, biologically based practices, manipulative and body-based practices, and energy medicine. The intended use of a product plays a vital role in the way it is regulated. Therefore, when a product satisfies the statutory definition of a drug, device, food, or biological product, it will face regulation under FFDC or PHS, or both.

Manufacturers of natural goods as well as holistic practitioners cannot promote their products or services as cures or treatments. They are allowed only to claim that the products or practices may promote a specific outcome. They also must include on the product’s label or on a practitioner’s advertisement an FDA disclaimer. Likewise, there is no assurance that natural goods are consistently formulated to guarantee strength, amount, and purity of the active ingredient in each dose. When using health therapies, choosing a suitable manufacturer is vital to confirm safety, intended use, and end result.

Future Challenges and Goals

CAM regulation affects a number of constituents, including health care providers trying to reduce the legal risks of integrating CAM into their biomedical practices; FDA officials and judges, attorneys, and legislators; credentialing and licensing agencies and organizations that standardize CAM-practice qualifications; consumers and patients hoping to access available wellness options; and insurers, clinics, and hospitals striving to integrate CAM therapies in health plans. As the FDA’s guidance is relatively young, these constituent groups are reshaping the developing legal authority for the coexistence of the safe and effective exercise of integrated health care. The FDA pursues a scientific regulatory model.

For CAM proponents, an ideal future includes forward-thinking regulation that sustains a broad, nonbiomedical, holistic, and neutral move that embraces wellness alternatives. The type of regulation needed will help integrate biomedicine and CAM so that consumers will be protected from fraudulent and dangerous therapies.

Bibliography

Astin, J. A. “Why Patients Use Alternative Medicine.” Journal of the American Medical Association 279 (1998): 1548-1553. Provides survey results of a study assessing what prompts consumers to use alternative medicine.

Briggs, J. P., and R. L. Nahin. “Cost of Complementary and Alternative Medicine and Frequency of Visits to CAM Practitioners.” Atlanta: Centers for Disease Control and Prevention, 2007. Results from the National Health Survey of 2007 regarding CAM-related spending in the United States.

Cohen, M. H., and K. J. Kemper. “Complementary Therapies in Pediatrics: A Legal Perspective.” Pediatrics 115, no. 3 (2005): 774-780. Examines the legal considerations of CAM therapies for pediatric patients.

Eisenberg, D. M., et al. “Credentialing Complementary and Alternative Medical Providers.” Annals of Internal Medicine 137, no. 12 (2002): 965-973. A review discussing the status and mechanisms of licensing and the establishment of standards of practice to protect patients.

Fontanarosa, P. B., and G. D. Lundberg. “Alternative Medicine Meets Science.” Journal of the American Medical Association 280 (1998): 1618-1619. An editorial that promotes scientific evidence-based methods for determining quality medicines and therapies.

Hutt, Peter B., Richard A. Merrill, and Lewis A. Grossman. Food and Drug Law: Cases and Materials. 3d ed. New York: Foundation Press, 2007. A brief account of the FDA’s administrative law. Deals with governmental attempts to protect public health and individual welfare in the development and marketing of essential products.

National Center for Complementary and Alternative Medicine. “Statistics on CAM Costs: 2007 National Health Interview Survey.” Available at http://nccam.nih.gov/news/camstats/costs. Provides statistics on CAM costs in the United States from the 2007 National Health Survey.

U.S. Food and Drug Administration. “Guidance for Industry on Complementary and Alternative Medicine Products and Their Regulation by the Food and Drug Administration.” Rockville, Md.: Author, December, 2006. The first FDA guidance on CAM in the United States.

What is acquired immunodeficiency syndrome (AIDS)?

Causes and Symptoms

Acquired immunodeficiency syndrome (AIDS) is caused by the human immunodeficiency
virus (HIV), a member of the lentivirus family of
retroviruses. This virus is thought to have arisen in Africa
in the early to mid-twentieth century from related viruses in the chimpanzee and
the sooty mangabey monkey. The virus cannot survive long in the air and cannot be
transmitted by casual contact. Individuals can be infected only by the exchange of
certain body fluids, including semen, vaginal fluid, blood, and breast milk. Other
body fluids such as sweat, tears, saliva, urine, and feces may contain HIV, but
the virus exists in such low concentrations that these fluids are completely
ineffective in transmitting an infection. The most common mode of transmission is
through vaginal and anal sex; it is also possible to transmit HIV by performing
oral sex, although this is less common than with vaginal or anal sex. The presence
of other sexually
transmitted diseases (STDs), such as gonorrhea, syphilis,
chlamydia, genital herpes, or human papillomavirus, dramatically increases the
risk of acquiring an HIV infection through sexual contact.

The second most common mode of transmission is through the sharing of needles or
syringes contaminated with HIV-positive blood. An HIV-positive pregnant woman may
transmit the virus to her child in utero, or more commonly during childbirth.
Mother-to-child transmission may also occur through breast-feeding in which the virus is present in the milk.
Early in the AIDS epidemic and before a blood test for HIV was available, blood
and blood products from blood banks were sometimes contaminated with HIV that
subsequently infected recipients. Indeed, more than 90 percent of patients with
hemophilia at this time became infected with HIV through injections of
HIV-contaminated clotting factor VIII. Because of the development of a heat
treatment for clotting factor VIII and the screening of the blood supply, patients
with hemophilia and other blood-transfusion recipients are no longer at high risk
for HIV infection. Although the blood supply is relatively safe today, a very low
probability of acquiring HIV through a transfusion of contaminated blood still
exists, as a recently infected donor may not yet test positive for HIV, although
this is phenomenon is extremely rare in developed countries.

Although HIV can infect virtually all cells of the body, it has a strong affinity
for cells of the immune system. The virus uses a cell surface receptor called
CD4 to bind to the membrane of a cell. The CD4 receptor is found on many cells in
the body but is in relatively high concentrations on the surface of a class of
T
lymphocytes called T4 or CD4 cells. The virus uses a
coreceptor called CXCKR4, also found on the membrane, that promotes the fusion of
the membrane of the virus particle with the membrane of the cell, thereby allowing
entry of the virus. Persons who lack the coreceptor on their cells appear to
resist infection by the virus. The T4 cells are also known as T-helper cells, as
they produce a series of chemical signals called lymphokines that are needed for
the development and maintenance of the entire immune system. While the body
constantly makes new T4 cells, HIV has a very small edge in the rate at which
these T4 cells are infected and destroyed. Thus, there is a slow but progressive
decrease in T4 lymphocytes in the body and loss of immune function. This process
may take ten or more years.

The clinical course of infection occurs in three stages. Initially upon infection,
HIV produces an acute retroviral syndrome referred to as the prodromal stage,
beginning about three to four weeks after initial infection and lasting for two to
three weeks. During a retroviral syndrome, the patient experiences flulike or
mononucleosis-like symptoms. The patient will believe that
he or she simply has a moderate-to-severe case of influenza or, if the symptoms
are prolonged, mononucleosis. During this period, HIV is rapidly proliferating,
disseminating throughout the body and infecting lymphoid tissues. Viral load is
high at this stage, and the patient is highly infectious. At the same time, the T4
cell count, which normally is about 1,000 per cubic millimeter, drops by about
half. The patient’s immune system will mount an antibody response against HIV, but
these antibodies are ineffective in stopping the infection. When such antibodies
are detectable, the patient is then said to have seroconverted. Anti-HIV antibody
detection by a simple blood test is the basis for assigning HIV-positive status.
In most cases, seroconversion occurs between six to eighteen weeks after
initial infection, although, in rare cases, antibodies may not be detectable until
later. By three months, 95 percent of patients will have seroconverted; by six
months, more than 99 percent will have detectable circulating antibodies to
HIV.

The second stage is called the clinical latency period or asymptomatic stage.
Without anti-HIV therapy, this period may last ten or more years. It is during
this time that the patient usually has no AIDS symptoms. Early in the latent
period, T4 cell counts usually recover somewhat during the first year of
infection, averaging approximately 700 per cubic millimeter. After that, there is
a very slow decline. In the meantime, viral loads, which were high during the
acute retroviral syndrome stage, drop by several orders of magnitude as the T4
count rises. At about one year into the infection, the viral load very slowly
increases as the latent period progresses.

The third phase of HIV infection is the development of AIDS. This usually occurs
when the T4 count drops below 200 per cubic millimeter. Opportunistic
infections and cancers become common, and patients may have
several infections simultaneously. Many of these diseases are rare in healthy
individuals. Most common is
Pneumocystis jiroveci

pneumonia, a form caused by a fungus that is virtually unseen in individuals with
a normal immune system. Indeed, the fungus is present in a majority of the
population yet almost never causes pneumonia unless the immune system is
compromised or suppressed. As one of the functions of the immune system is to
destroy cancer cells when they arise, patients with AIDS are at a
substantially higher risk of developing some types of cancers compared to
uninfected individuals of the same age. One of these cancers is Kaposi sarcoma, a
normally very rare tumor of blood vessels characterized by pink to purple spots or
slightly raised areas on the skin. These lesions may
also arise on internal organs, where they can impair function. Kaposi’s sarcoma is
caused by human herpes virus 8 (HHV8) and is sexually transmitted. Individuals
with AIDS are several thousand times more likely to develop Kaposi sarcoma than
uninfected individuals. The other cancer commonly associated with AIDS is
non-Hodgkin
lymphoma, often in the brain. Patients with AIDS are nearly
seventy times more likely to be diagnosed with non-Hodgkin lymphoma.

In 1987, the US Centers for Disease Control (CDC) published the criteria for the
diagnosis of AIDS, including the appearance of one or more opportunistic
infections or cancers. Twenty-three different conditions were listed in the
definition: candidiasis of the bronchi, trachea, or lungs; esophageal
candidiasis; disseminated or extrapulmonary coccidiomycosis; extrapulmonary
cryptococcosis; chronic intestinal cryptosporidosis (greater than one month in
duration); cytomegalovirus disease (other than liver, spleen, or lymph
nodes); cytomegalovirus retinitis (with loss of vision); HIV encephalopathy;
herpes simplex causing chronic ulcers (greater than one month in
duration) or bronchitis, pneumonitis, or esophagitis; disseminated or
extrapulmonary histoplasmosis; chronic intestinal isosporiasis
(greater than one month in duration); Kaposi sarcoma; Burkitt
lymphoma; immunoblastic lymphoma; primary lymphoma of the
brain; Mycobacterium avium complex or M.
kansasii; extrapulmonary infection due to Mycobacterium
tuberculosis; other or unidentified Mycobacterium
species; Pneumocystis jiroveci pneumonia; progressive multifocal
leukoencephalopathy (PML); recurrent
Salmonella
septicemia; toxoplasmosis of the brain; and wasting
syndrome caused by HIV. In 1993, three conditions were added to the criteria:
pulmonary tuberculosis, recurrent pneumonia, and invasive cervical carcinoma.
Moreover, the definition was expanded to include any HIV-positive person whose T4
count had dropped to 200 per cubic millimeter or lower or whose level of T4
lymphocytes had fallen to 14 percent or less of total lymphocytes.

For the diagnosis of HIV infection, the CDC recommends laboratory evidence from a
positive HIV antibody screening test, such as a reactive enzyme immunoassay, that
is confirmed by a positive result from a supplemental HIV antibody test or a
positive result from HIV nucleic acid detection test such as polymerase chain
reaction (PCR) or HIV virologic tests such as HIV p24 antigen
test or HIV viral culture. The Infectious Disease Society of America recommends
diagnosing HIV infection by a rapid HIV test or conventional enzyme-linked
immunosorbent assay (ELISA) and confirmed by Western blot or indirect
immunofluorescence assay; if the initial testing is negative or indeterminate it
should be repeated four weeks later.

Treatment and Therapy

As of 2014, no effective vaccine had been developed to prevent HIV infection.
While a number of candidate vaccines have been under development and in clinical
trials, none has proven successful. The usual strategies used with most antiviral
vaccines in the past, immunization with attenuated or inactivated viruses, have so
far proven ineffective for HIV given its significant rate of mutation. Control of
the epidemic has shifted significantly toward preventing exposure and decreasing
infectivity by treating to reduce viral load, a measure of the number of viruses
in blood and in body fluids.

AIDS treatment and therapy fall into two categories: prophylaxis and the
prevention and treatment of opportunistic infections to slow progression to
full-blown AIDS. Treatment of opportunistic infections must follow established
guidelines for the individual disease. Thus, in the treatment of Kaposi sarcoma,
surgery, chemotherapy, and radiation treatment singly or in
combination are utilized. Bacterial and yeast or other fungal infections are
treated with antibiotics or antifungal agents. Although some medications
may reduce the severity of viral infections, such infections are
not easily treated. Because a person with AIDS might suffer from more than one
opportunistic infection and/or cancer at the same time, simultaneous treatments
often take a severe toll on the patient. Without treatment, individuals who
progress to AIDS survive approximately three years. Death typically results from
an opportunistic infection or cancer. However, HIV-positive individuals who
undergo antiretroviral therapy (ART) to maintain a low viral load typically have a
life expectancy similar to HIV-negative individuals and never progress to
AIDS.

This strategy for HIV treatment involves interfering with the viral life cycle
with the aim of slowing viral replication. Anti-HIV drugs target several steps in
the life cycle, primarily at the levels of reverse transcription or assembly. In
1987, the first generation of drugs was developed to treat HIV. The first
effective treatment utilized zidovudine (ZDV), commonly called azidothymidine
(AZT), a drug originally developed for chemotherapy of cancer. ZDV inhibits the
viral encoded enzyme, reverse transcriptase, involved in copying the RNA viral
genome into a DNA copy. As a result, a nucleoside analogue is inserted into the
growing DNA, which stops further synthesis of the DNA copy. Other nucleoside
reverse transcriptase inhibitors (NRTIs) that have a similar effect include
emtricitabine, tenofovir, and abacavir. In a similar manner, the nucleotide
analogue tenofovir blocks DNA replication. Nevirapine and efavirenz are
non-nucleoside drugs that bind directly to and inhibit reverse transcriptase.
Although this group of drugs inhibits reverse transcriptase, their mode of action
is different from nucleoside or nucleotide analogues.

The final step in HIV replication involves the cleavage of a large precursor
protein into smaller structural proteins, an event taking place at the cell
surface and followed by release of the completed virus. The cleaving enzyme is
called a protease and is encoded by the virus. The second generation of anti-HIV
drugs, which were developed in the 1990s, were protease inhibitors, drugs that
interfere with cleavage of the precursor and prevent viral assembly. As a result,
functional virions cannot be made. Atazanavir, darunavir, fosamprenavir,
indinavir, lopinavir, and ritonavir are approved drugs in this class. Other types
of anti-HIV drugs called fusion inhibitors (for example, enfuvirtide) interfere
with entry of the virus into a cell. In addition, integrase inhibitors, such as
raltegravir, may be used. Integrase inhibitors prevent the DNA copy of the virus
from inserting itself into one of the cell’s chromosomes. Thus the anti-HIV
arsenal includes drugs that act at different sites or stages in the HIV life
cycle.

The HIV reverse transcriptase makes numerous mutations during the synthesis of
DNA. Consequently, resistance to individual anti-HIV drugs arises easily and
frequently. Beginning in 1995, a new strategy for anti-HIV therapy called highly
active antiretroviral therapy (HAART), also known as AIDS cocktail therapy, was
developed. HAART consists of using a combination of three or more anti-HIV drugs,
including two reverse transcriptase inhibitors and at least one protease
inhibitor. HAART therapy is very effective, as it has been
estimated that it prolongs the life expectancy of a person with AIDS by three to
ten years. Moreover, many patients with AIDS and in terminal stages of the disease
have made remarkable recoveries when placed on HAART. In many cases, viral loads
were dramatically reduced, T4 cells made some recovery, and the incidence of
opportunistic infections was reduced. Another advantage of multiple drug therapy
is that the probability of HIV developing simultaneous resistance to three or four
different drugs is very low, extending the useful therapeutic life of the
individual drugs.

The long-term effectiveness of HAART is underscored by an examination of the AIDS
deaths in the United States. In 1981, the CDC began to track the number of AIDS
deaths. Each year, the number of deaths climbed steadily, reaching a peak of
50,610 in 1995. In 1996, the first full year of widespread HAART therapy, AIDS
deaths dropped by 25 percent, and they have continued to drop every year since. In
2012, an estimated 1.6 million people died of the disease worldwide, down from
approximately 2.3 million in 2005.

Perspective and Prospects

AIDS was first recognized as a new disease in the United States in late 1980.
Michael Gottlieb at the University of California, Los Angeles (UCLA) diagnosed men
who have had sex with men with Pneumocystis carinii pneumonia and
Kaposi sarcoma, diseases that in the past were extremely rare. In June 1981, the
CDC alerted doctors in a report on this new epidemic for the first time in the
CDC Weekly Morbidity and Mortality Report. Shortly thereafter,
the New York Times reported on the new “gay cancer.” At first,
the disease was called gay-related immunodeficiency (GRID). The name GRID was changed to
acquired immunodeficiency syndrome, or AIDS, in an August 8,
1982, article in the New York Times, representing the first time
that the term was used in a publication. The change reflected the fact that this
new disease was not restricted to men who have had sex with men; cases involving
intravenous drug users, individuals with hemophilia and other blood-transfusion
recipients, and infants were being diagnosed. In January 1983, Luc
Montagnier and colleagues at the Pasteur Institute in Paris
were the first to isolate the virus causing AIDS. It was given the name human
immunodeficiency virus, or HIV, in 1985; previously, the virus had been given
several names by different researchers. With the isolation of the virus, a blood
test could be developed.

Testing of blood and blood products started in March 1985. A test called
enzyme-linked immunosorbent assay (ELISA) screens for the presence of anti-HIV
antibodies. Results once took weeks, but the test is now automated and is
performed within hours.

HIV has been confirmed in the United States since at least 1969. At that time, a
physician in St. Louis, Missouri, had a young male patient with a variety of AIDS
symptoms. After the patient died, the pathologist took samples of his tissues and
froze them. Later, when tests to detect HIV became available, the tissue samples
were tested and found positive for HIV. The oldest positively identified HIV
sample came from blood collected from a male patient by a Belgian physician in
Kinshasa, Democratic Republic of the Congo. The doctor had saved many blood
samples taken between 1959 and 1982; thus, the earliest confirmation of HIV
infection in Africa dates from 1959. The virus has probably been present in the
human population for much longer, but without blood or tissue samples, this cannot
be confirmed.

Two major classes of HIV have been identified: HIV-1, which arose in Central
Africa, and HIV-2, which arose in Western Africa. HIV-1 and HIV-2 have long been
known to be genetically similar to viruses know as simian immunodeficiency viruses
(SIV) in chimpanzees (SIVcmp) and the sooty mangabey monkey (SIVsm). In 2006,
scientists determined that in all likelihood, HIV-1 originated in chimpanzees from
regions of the nation of Cameroon; as many as one-third of chimpanzees from some
colonies were found to carry SIV. The first confirmed human infection was that of
a man from the nearby Congo, who developed AIDS in 1959. However, evidence
suggests that HIV may have emerged in humans as early as 1930.

According to the CDC's HIV Surveillance Supplemental Report, 2011
(2013), an estimated 1.14 million persons aged thirteen and older are living with
HIV infection in the United States, including nearly 181,000 people who are not
aware of the infection; approximately 15,500 persons with an AIDS diagnosis died
in the United States in 2010, although these deaths may or may not be related to
AIDS. Worldwide, the World Health Organization (WHO) estimates that seventy-five
million people have been infected with the HIV virus since the beginning of the
epidemic and approximately thirty-six million people have died of HIV/AIDS.
Worldwide, an estimated 35.5 million people were living with HIV infection at the
end of 2012, and an estimated 1.6 million people died of AIDS-related illnesses in
2012. The WHO estimates that 0.8 percent of people aged fifteen to forty-nine
years worldwide are living with HIV, although the vast majority of people with HIV
live in low- and middle-income countries, where prevention and treatment efforts
are limited. Sub-Saharan Africa is the most severely affected region of the world,
with an estimated 24.9 million adults and children living with HIV in 2012.
However, the number of people dying from AIDS-related causes in sub-Saharan Africa
declined by more than 50 percent from 2004 and 2012, as prevention and treatment
efforts in the region improve.

Several new medications in development will hopefully enlarge the arsenal of
anti-HIV drugs, further extending the life expectancies of individuals with
HIV/AIDS. The success of HAART promises to extend the life of persons with AIDS by
many years, and with adequate treatment many HIV-positive individuals enjoy life
expectancies equal to those of HIV-negative individuals. A significant issue is
the high financial burden of HAART therapy. A typical HAART regimen may cost
$1,500 to $2,000 per month. Although many people in high-income countries can
purchase these drugs through insurance providers or government subsidy, this
financial burden precludes the use of HAART and many anti-HIV drugs in low- and
middle-income countries, where HIV prevalence is highest. Thus, effective
prevention of HIV infections, through vigorous public education about HIV and
AIDS, is absolutely critical. Such a program in Uganda dramatically reduced the
incidence of HIV infections, showing the effectiveness of public education
campaigns. According to the United Nations, although the number of individuals
living with HIV/AIDS has risen between 2005 and 2013, the number of adults and
children newly infected with HIV has declined from 2.9 million in 2005 to 2.1
million in 2013; the number of AIDS-related deaths has also declined from 2.4
million to 1.5 million in the same time period.

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