AIDS and HIV: Prevention of HIV Infection

Protecting the Blood Supply

Early in the epidemic, before the virus was identified and procedures to test the blood supply were available, some people were infected by contaminated blood or blood products. Persons requiring frequent blood transfusions, such as those undergoing surgery or being treated for hemophilia, were most vulnerable to this mode of HIV transmission.

In 1985, it became possible to test blood for antibodies (molecules in the blood that are released to neutralize or destroy bacteria, viruses, or other microorganisms that invade the body) to HIV. Known as ELISA, or the enzyme-linked immunosorbent assay, this test identifies blood that may be infected with HIV.

Since 1985, efforts to prevent transmission of HIV through blood transfusions have relied on three strategies. First, all donated blood is now tested for HIV antibodies (as well as for hepatitis and syphilis). Second, potential blood donors with high-risk histories are not allowed to donate blood. Third, blood products that are infected with HIV are discarded.

Although there remains a very minute risk of receiving HIV-infected blood in a transfusion (the antibody test used to detect HIV is not 100% perfect and blood donors who have been infected with HIV very recently may not develop antibodies for a few weeks), the likelihood of such transmission in the United States and most developed countries is now extremely low. Nucleic acid testing, a procedure that screens blood for HIV directly, promises to increase the safety of the blood supply even further in the coming years.

The blood supply outside of the United States and other developed countries remains a source of concern. Many developing countries cannot afford to screen their blood products and transmission via this mechanism continues.

Minimizing Occupational and Accidental Exposures to HIV

Occupational exposures to contaminated blood and accidental needle-sticks among health care workers have led to some documented cases of HIV in the United States. The number of actual infections caused by this route is relatively small, but such infections have been reduced further in the United States through several prevention strategies.

One strategy involves the adoption of “universal precautions” procedures. Universal precautions begin with the assumption that all patients in health care settings could be infected with HIV; therefore, emergency medical personnel, health care workers, and others likely to come into contact with bodily fluids automatically protect themselves by wearing latex gloves and other protective coverings when caring for their patients. In addition, health care workers are required to dispose of uncapped needles and syringes in specially made, puncture-resistant containers. Universal precautions procedures also involve the incineration (or careful discarding in heavy-duty plastic bags) of medical waste, trash, and linens in hospitals and other health care settings.

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