HIV (Human Immunodeficiency Virus) is the virus that causes AIDS (Aquired Immune Deficiency Syndrome).
ORIGIN OF THE VIRUS
The generally accepted hypothesis as to how the virus came into existance is that the Simian Immunodeficiency Virus (which infects chimpanzees) made the leap from chimps to humans early in the 20th century, after years of tribes of Africans consuming the flesh of chimps infected with the virus.
STAGES OF THE VIRUS
There are 4 main stages of infection: the incubation period, acute infection, latency stage, and full-blown AIDS.
During the incubation period (which begins at the moment of infection and generally lasts between 2 and 4 weeks), patients are usually (but not always) asymptomatic (meaning they present no symptoms).
ACUTE INFECTION PERIOD
Next comes the acute infection period (generally lasting 28 days), in which symptoms are very similar to those of the flu, such as swollen lymph nodes, sore throat, sore and weak muscles, and fever.
After the acute infection period comes the latency stage where patients will again experience few or no symptoms. This can last anywhere from 2 weeks to 20 years (or longer). It is the objective of physicians to keep the virus in this latency period for as long as possible in order to lengthen patients' lives.
And finally comes full-blown AIDS. This last stage is characterized by a CD4+ T cell (cells that help fight infection) cou...