All "look-back" investigations of the practices of dentists and physicians infected with the HIV rely heavily on the cooperation of the infected health care workers and are limited by incomplete assessment of former patients. Nonetheless, these investigations have been extremely helpful in documenting the very small risk for HIV transmission in such settings. Given the potential for litigation if patients are found to have acquired HIV infection during dental or medical care, we reassert our belief that patients would probably participate in an investigation to determine the source of their infection.

Dr. Lewis indicates that he is aware of persons in Florida who believe that they were infected with hepatitis B or C virus or with HIV through exposure to contaminated dental or medical devices. Without a complete epidemiologic and laboratory investigation, however, these anecdotal reports cannot be interpreted. We urge the physicians who care for such patients to consult with their local or state health departments regarding follow-up investigation.