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HIV-1 is the virus that causes almost all the cases of AIDS worldwide. A related virus, HIV-2, was first isolated in people in West Africa in 1986. Some people who are infected with HIV-2 appear to have an AIDS-like illness, but most do not have symptoms.

You should be tested for HIV-2 infection if you:

• Are from West Africa and practice high-risk behaviors, such as having more than one sex partner or injecting illegal drugs.
• Have a sex partner who is from West Africa.
• Received a blood transfusion in West Africa.
• Are a child whose mother is infected with HIV-2.
• Have developed opportunistic infections but do not test positive for HIV-1 infection. These opportunistic infections may include:
  • Pneumocystis pneumonia.
  • Tuberculosis.
  • Toxoplasmosis.
  • Cytomegalovirus (CMV).
  • Mycobacterium avium complex (MAC).

Because HIV-2 is transmitted in the same ways as HIV-1, people who have HIV-2 should follow the same precautions as people who have HIV-1. It is possible to be infected with both HIV-1 and HIV-2.

Since 1992, blood and organs donated in the United States have been screened for HIV-2, so the risk of developing HIV-2 infection from a blood transfusion or organ transplant is extremely low.