Wednesday 4 March 2015

What is rheumatic fever? |


Causes and Symptoms


Rheumatic fever is an inflammatory disease affecting the heart that may follow infection by the bacterium Streptococcus pyogenes. The streptococci constitute a large number of gram-positive cocci, some of which are pathogens. They were originally classified in the 1930s by Rebecca Lancefield into groups based on characteristics of carbohydrates and proteins in their cell walls. S. pyogenes is the sole species of streptococcus in group A. Group A streptococcus causes a wide array of illnesses, most notably pharyngitis (causing strep throat) and impetigo. The most serious complication associated with infection by specific strains of S. pyogenes is rheumatic fever.


Rheumatic fever may develop one to five weeks after recovery from a streptococcal infection, often strep throat. The onset is sudden, with the patient exhibiting severe polyarthritis, fever, and abdominal pain. There may be chest pain and heart palpitations. Transient circular lesions may develop on the skin. Rheumatic nodules may be noted on joints and tendons, along the spine, and even on the head. Sydenham’s chorea, the exhibition of irregular body movements, may also appear during the course of the illness. In severe cases, the patient may become incapacitated.


While there is no specific diagnostic test for rheumatic fever, the combination of clinical symptoms may suggest its onset, particularly if there was a recent sore throat. The production of serum antibodies against streptococcal antigens is also indicative of rheumatic fever.


Most of the time, the symptoms subside with bed rest. Mild cases generally last three or four weeks, while more severe cases may last several months. A single bout with rheumatic fever may be followed by recurrent episodes with additional infections by B hemolytic streptococci.


Rheumatic fever is an autoimmune phenomenon. Certain proteins in specific strains of group A streptococcus contain segments that cross-react with heart tissue, including that found in muscle and valves. As the body responds to the streptococcal infection, the immune response may also involve cardiac tissue, resulting in inflammation and possible damage. Since the immune reaction occurs over a period of days to weeks, the onset of rheumatic fever may be considerably removed from the actual infection.




Treatment and Therapy

Because rheumatic fever represents an autoimmune reaction to an earlier streptococcal infection, antibiotic treatment is of limited value. Penicillin or similar antibiotics may be administered for their prophylactic value, preventing further streptococcal infection and recurrence of the illness during the recovery period.


Bed rest and restriction of activities is recommended during the course of the illness. The patient should receive large amounts of fluids. Steroids or other anti-inflammatory compounds may also be administered in response to severe polyarthritis or valvular inflammation. The duration of such inflammation is generally no more than two weeks.


Repeated infections with streptococci may trigger additional episodes of rheumatic fever, so antibiotics may be administered on a regular basis. While not all streptococcal infections trigger rheumatic fever, any previous cardiac episode is likely to be repeated after an additional streptococcal infection, often resulting in greater damage. For this reason, prophylactic antibiotic treatment may be long term.


If rheumatic heart disease has resulted in permanent damage to heart tissue, additional therapies may be necessary. Often, such damage may not be apparent for years. Thickening or scarring of the heart valves, particularly the mitral and aortic valves, may necessitate valve replacement at some point in the future.




Perspective and Prospects


Thomas Sydenham, called the “English Hippocrates,” in 1685 provided the first description of what was probably rheumatic fever. He also described what has become known as Sydenham’s chorea, now known to be symptomatic of rheumatic fever. In 1797, London doctor Matthew Baillie noted the damage to heart valves among patients suffering from the illness. The association of rheumatic fever with bacterial infection, however, was not established until well into the twentieth century.


In part this delay resulted from the inability to isolate an organism either from the diseased heart or from blood of patients with rheumatic fever. In 1928, Homer Swift, a New York physician, suggested that rheumatic fever was an allergic response following streptococcal infections. A few years later, the role of serologic group A, B hemolytic streptococci as the actual agent associated with the disease was established by Alvin Coburn.


A decline in the incidence of rheumatic fever in the United States began in the first decades of the twentieth century. The reason is unclear in this period before antibiotics; the decrease may have been attributable in part to the presence of less virulent strains of the bacteria. With the introduction of penicillin in the 1940s as an effective treatment for streptococcal infections, the incidence of acute rheumatic fever continued its decline.


A resurgence of the disease was first noted in the 1980s. The reasons remain unclear. Since different strains of streptococci differ in their ability to induce rheumatic fever, it is suspected that the increase may have resulted from the introduction of new bacterial strains into the population. The disease has also been seen to cluster in families, suggesting that a genetic predisposition may exist in the general population which contributes to the rise in numbers of cases. Fortunately, the streptococci have not yet established the widespread resistance to antibiotics seen among other bacteria, and rheumatic fever as a sequela to streptococcal pharyngitis may be prevented with proper treatment.




Bibliography


English, Peter C. Rheumatic Fever in America and Britain: A Biological, Epidemiological, and Medical History. New Brunswick, N.J.: Rutgers University Press, 1999.



Kiple, Kenneth F., ed. The Cambridge World History of Human Disease. New York: Cambridge University Press, 1999.



McCance, Kathryn L., and Sue M. Huether. Pathophysiology: The Biologic Basis for Disease in Adults and Children. 6th ed. St. Louis, Mo.: Mosby/Elsevier, 2010.



Murray, Patrick R., Ken S. Rosenthal, and Michael A. Pfaller. Medical Microbiology. 7th ed. Philadelphia: Mosby/Elsevier, 2013.



"Rheumatic Fever." Health Library, March 15, 2013.



"Rheumatic Fever." Mayo Clinic, January 21, 2011.



Steeg, Carl N., Christine A. Walsh, and Julie S. Glickstein. “Rheumatic Fever: No Cause for Complacence.” Patient Care 34, no. 14 (July 30, 2000): 40–61.



Woolf, Alan D., et al., eds. The Children’s Hospital Guide to Your Child’s Health and Development. Cambridge, Mass.: Perseus, 2002.

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