A dentist showed symptoms of HIV infection in late 1986, and was diagnosed with AIDS in 1987. At the time of the AIDS diagnosis, AZT therapy was begun, discontinued for a short period in late 1987, then restarted and continued until his practice closed in 1989. All of the dentist's employees, including the dental hygienists, tested negative for HIV antibodies.
The dentist wrote an open letter to his former patients, which prompted 591 persons to be tested for HIV antibodies. The following list summarizes the seropositive individuals.
* Patient F was an infrequent sex partner of patient E. Their last contact was in the fall of 1988.
tTested seronegative in October and December 1988, positive in December 1990.
1. Analyses of DNA and amino acid sequences from HIV isolated from the patients strongly suggest that five of the patients were infected by the dentist. Which two were not? How did you arrive at your conclusion?
2. How can transmission of HIV and hepatitis B by health-care workers be prevented?
1. Patients D and F were probably not infected by the dentist.
2. See the box in Chapter 13 of Microbiology: An Introduction.
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