... When a woman is treated with the antiretroviral drug, AZT, the risk of passing it onto her child significantly decreases. HIV is a retrovirus that replicates itself inside of cells. HIV belongs to a group of viruses known as lent viruses or "slow viruses." This classification is because of the long periods of time between infection and the onset of more serious illnesses. When HIV enters the body, it starts to multiply and attack the cells of the immune system known as CD4 + T cells. CD4 + T cells are the immune system's primary infection fighters. Over time, the body's CD4 + T cell count gradually declines. A person is diagnosed with AIDS when their CD4 + T cell count drops below 200 per cubic millimeter of blood. An uninfected person has a count between 600 and 1500 per cubic millimeter of blood. When this drop in cell count occurs, patients are prone to develop opportunistic infections that define the AIDS virus. In developing countries where healthcare and technology used to determine a person's CD4 + T cell count is limited, AIDS is diagnosed by the presence of signs associated with immunodeficiency syndrome and the exclusion of other immunosuppression infections such as cancer or malnutrition. Scientists believe that HIV originated from its equivalent virus, known as simian immunodeficiency syndrome or more commonly SIVcpz, found in chimpanzees. SIVcpz is related to HIV, which mostly appears in human blood. Laboratory tests have found that various SIVcpz strains can infect and replicate themselves with human blood. SIVcpz transferred from chimpanzees to humans in African communities where chimpanzees were hunted for food. Urbanization, introduction of needles, and various aspects of modernization contributed to SIVcpz adapting to human beings (Cohen, 6). Another group of scientists believe the virus entered humans because of human error. In the late 1950s, scientists began to test a strain of a polio vaccine on people living in South Africa. Some believe that the vaccine might have been made from blood of monkey kidneys that was tainted with the HIV infection. Still, many believe the AIDS epidemic started centuries before the first case was reported in 1981. This theory is possibly true due to the fact that AIDS is not caused by a single disease with a single symptom. ...
