What are three viral diseases? What are their causes and methods of prevention?

Viral diseases are diseases specifically caused by pathogenic agents called viruses. Viruses are small infectious agents that replicate inside the cell and depend on the host's replication mechanism to survive. They are not living organisms, per se, as they lack basic functions of living organisms, such as the ability to reproduce (when outside the host). 

Here are three examples of viral diseases:

Common cold- it may seem like a very simple and common disease,...

Viral diseases are diseases specifically caused by pathogenic agents called viruses. Viruses are small infectious agents that replicate inside the cell and depend on the host's replication mechanism to survive. They are not living organisms, per se, as they lack basic functions of living organisms, such as the ability to reproduce (when outside the host). 

Here are three examples of viral diseases:

Common cold - it may seem like a very simple and common disease, but the common cold is actually a viral disease caused by the parainfluenza virus

AIDS - a sexually-transmitted disease that is highly complex in nature, AIDS is caused by the Human Immunodeficiency Virus (HIV)

Chickenpox - a common disease caused by the Varicella-zoster virus; a related and deadly disease that has been eradicated is small pox, which is caused by the variola virus

While viruses attack via different mechanisms, they have one common theme of infection: they hijack the host's DNA replication machinery to multiply and infect cells. Once infected, a cell can die and burst, releasing more of the viruses and infecting more cells.

Unlike bacterial infections, which can be treated by killing the bacteria using anti-bacterial agents, viral infections cannot be treated. The symptoms can be managed, but there isn't any cure. This is why there still isn't a cure to the common cold.