Exposure to HIV-infected blood poses a definite risk for HIV infection for health care, laboratory, and home health care workers. Large prospective collaborative studies have found the risk of seroconversion following needle stick or other parenteral exposures to the blood of HIV-infected persons to be approximately 0.3%. In addition, there are a few well-documented, published reports of infections in health care workers following mucous membrane or extensive skin exposures. Such transmission can occur, but the risk is much lower than following parenteral exposures.

The use of zidovudine after occupational exposures (needle stick injuries) has been shown to decrease the risk of HIV seroconversion among exposed health care workers. The USPHS has recently recommended the use of combination antiretroviral chemoprophylaxis, including a protease inhibitor, after high-risk percutaneous exposures.

Transmission of HIV infection from an infected dentist to six patients and the transmission from a surgeon to a patient remain the only documented transmissions of HIV to patients from health care workers.

These patients had no other confirmed exposure to HIV and each was infected with an HIV strain nearly identical genetically to that of the health care worker and dissimilar to that of other HIV-infected persons in the area. Rarely, HIV infection transmission has been reported through inadvertent intravenous injection of blood from HIV-infected patients in home health care or hospital settings. Major nosocomial HIV outbreaks resulted from improper sterilization or reuse of contaminated injection equipment in Romania and in the former Soviet Union.

The risk of transmission of HIV, hepatitis B and C viruses, and other blood borne pathogens to and from health care workers and patients can be minimized by close adherence to recommendations, which include universal precautions when caring for all patients.