The virus responsible for AIDS was identified in 1938 and named Human Immunodeficiency Virus, or HIV. HIV primarily infects those cells of the immune system known as helper T cells, but it also may infect brain or nerve cells.
HIV Target Cells in Body
Helper T cells, brain cells, and nerve cells all have a particular cell surface molecule called CD4 that serves as the site of attachment for the virus. Inside the host cell, the viral RNA is copied into DNA which may be integrated into the host cell genome. Each infected cell can serve as a factory for the production of HIV.
When the cell eventually ruptures hundreds of viruses each able to infect another cell, are released. Reproduction of HIV in helper T cells leads to a gradual decline in the number of helper T cells, the weakened function of the immune system, and increased susceptibility to opportunistic infections and cancer. Opportunistic infections are normal infections, a fully functioning immune system would be able to repel. Although HIV can damage organs directly it is the opportunistic infections that account for up to 90% of deaths from AIDS.
HIV Incubation Period and Opportunistic Diseases
The incubation period for HIV infection is 2 weeks to three months. If an infection has occurred, HIV antibiotics can be detected in the blood at that time. The incubation period for AIDS is much longer. An individual infected with HIV may not develop AIDS for several months or even as long as 12 times the virus remains inactive in the cells of the immune system. Symptoms vary widely depending on the type and number of opportunistic diseases that occur and often alternate with periods of relatively good health.
AIDS the most severe stage of HIV infection usually leads to death within 2 years of diagnosis. Diagnosis is based on the presence of certain infections or cancers in a person who tests positive for HIV antibodies.
Among those conditions are a variety of infections caused by fungi, protozoans, eubacteria, and other viruses seldom seen in the population and the type of skin cancer known as Kaposi’s sarcoma. Besides Kaposi’s sarcoma, the most common opportunistic infection associated with AIDS is pneumonia caused by a protozoan parasite Pneumocystis carinii.
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