AIDS Underlying Cause
Viruses are very small particles that reproduce inside cells.
A normal cell uses DNA as a code for producing proteins, which regulate the cell's function. In order to reproduce, viruses take over the mechanism for producing proteins inside the cell, interrupting cell functions and eventually causing the cell to die.
HIV weakens the immune system, which fights infection. As part of the immune system, white blood cells help kill bacteria, viruses and fungi. The viruses enter white bloods cells, take over, and destroy the cells.
After the initial infection with HIV, a person may have no signs of AIDS for months to years, because it takes time for the virus to destroy the white blood cells. When enough of the white blood cells are destroyed, then the immune system becomes deficient: it is unable to protect the body from infection. Those who develop AIDS suffer from severe infections and cancers that are rare in those who have healthy immune systems.
The exact origin of HIV is unknown, but it is suspected to have come from Africa.
Studies suggest that chimpanzees, native to West Africa, were the origin of HIV. Experts feel that chimpanzees have harbored a similar virus, called SIVcpz for a few hundred thousand years. Unlike humans, infected animals do not develop AIDS from this virus. Transmission of the virus from the animal to the human population may have been through a contaminated bites or scratches, or from eating these animals. At some point, the virus changed, or mutated, into HIV.
The oldest case of HIV infection has been authenticated from a blood sample collected in 1959 from an African man.
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