In July 1990, the first case of possible transmission of HIV from an infected health care worker (dentist) to his patients was reported. Six patients are believed to have acquired infection from the dentist based on the absence of other risk factors among the patients and the high degree of homology between the viruses isolated from the dentist and those isolated from the patients. Although each patient underwent an invasive procedure in the dental office, the precise mode of transmission remains unknown.

Based on the known transmission of other blood-borne pathogens from health care providers to their patients (e.g., hepatitis B), it was anticipated that HIV may also be transmitted in this fashion. Remarkably, despite the prolonged duration of the epidemic, the dentist described above remains the only documented case of transmission to patients in the health care setting.

Several “look-back” studies of over 4000 patients who underwent invasive surgical procedures performed by HIV-infected physicians have failed to identify any additional cases of nosocomial transmission. Therefore, the risk of transmission from infected health care workers to patients is thought to be very low (between 1 in 42,000 and 1 in 420,000). Routine use of universal precautions should minimize the risk of transmission from HIV-infected patients to health care providers and vice versa.