Skip directly to search Skip directly to A to Z list Skip directly to site content
CDC Home

Update: Investigations of Patients Who Have Been Treated by HIV-Infected Health-Care Workers

Investigation of the patients of a Florida dentist with acquired immunodeficiency syndrome (AIDS) concluded that human immunodeficiency virus (HIV) was transmitted to five (0.5%) of approximately 1100 patients who were evaluated (1-3). Although the precise events resulting in transmission of HIV to these patients are not known, the findings of the investigation support direct dentist-to-patient transmission, rather than a patient-to-patient route. This report summarizes information from other published studies of patients who were treated by HIV-infected health-care workers (HCWs) (4-10), as well as from completed and ongoing unpublished investigations that have been reported to CDC.

In addition to the patients in the Florida dental practice, as of May 13, 1992, CDC was aware of HIV test results for 15,795 patients who were treated by 32 HIV-infected HCWs. The total number of patients treated by these HCWs and the number of patients who underwent invasive procedures are not known. No seropositive persons were reported among 10,270 patients who were tested from the practices of 23 of these 32 HCWs. The 23 HCWs comprised 11 dentists/dental students, six surgeons/obstetricians, and six other physicians in various nonsurgical subspecialties. For the remaining nine HCWs (five dentists and four surgeons/obstetricians), 5525 of their patients were tested, and 84 HIV-infected patients were identified.

Follow-up has been completed for 47 of the 84 seropositive patients: seven patients had established risk factors identified (e.g., male-to-male sexual contact, injecting-drug use, receipt of a blood transfusion from a retrospectively identified HIV-infected donor); five were documented to be infected before receiving care from the HIV-infected HCW; and the remaining 35 were male inmates in a state correctional facility. These 35 inmates were among a total of 962 male inmates who received treatment from two HIV-infected dentists and for whom HIV-antibody test results are known. The rate of HIV infection for inmates tested (3.6%) was less than that documented among male inmates upon entrance into the state correctional system (8.6%). Established risk factors were identified for 33 of the 35 inmates. Because both dentists have died, specimens for HIV genetic sequence analysis are not available. Further investigation of these infected inmates is not planned.

The 37 HIV-infected persons for whom investigations are in progress were patients treated by the following three HCWs:

Dentist 1. This dentist practiced in an area with a high background prevalence of HIV infection. Of 1162 patients tested thus far, 29 are HIV-infected. Established risk factors could not be identified for 17 of the 29 patients, but epidemiologic investigations determined that many may have had opportunities for exposure to HIV (e.g., multiple sex partners and/or exchange of sex for drugs or money). HIV genetic sequence analyses are in progress at CDC for the dentist and the infected patients.

Dentist 2. More than 800 patients of this dentist were tested, and five were positive for HIV antibody. Epidemiologic investigations have been completed for all five patients: three patients had established risk factors identified; a fourth patient was documented to be seronegative 18 months after the last visit to the dentist but was seropositive when retested 2 years after the seronegative test result. For the remaining patient, no risk factors were identified. This patient had one visit to the dentist for an examination. HIV genetic sequence analyses are under way at CDC for the dentist and the five infected patients.

Surgeon 1. Three of 328 patients who were tested were positive for HIV antibody. Preliminary information suggests that risk factors are likely for all three persons; investigations are in progress.

Reported by: Local, state, and territorial health departments. HIV Infections Br, Hospital Infections Program, and Div of HIV/AIDS, National Center for Infectious Diseases; Div of Oral Health, National Center for Prevention Svcs; National Institute for Occupational Safety and Health, CDC.

Editorial Note

Editorial Note: Data from these investigations, as well as risk estimates derived from modeling techniques (11), continue to indicate that the risk for HIV transmission from an infected HCW to a patient during an invasive procedure is very small. The investigation of a dental practice in Florida remains the only instance in which transmission of HIV from an infected HCW to patients has been reported (1-3). Although ongoing patient-notification programs have identified 84 additional HIV-infected patients who were treated by an infected HCW, follow-up thus far has not demonstrated transmission from a HCW as the source of HIV infection for any of these persons.

The finding of seropositive patients in these investigations is to be expected because an estimated one in 250 persons in the United States is infected with HIV (12). Higher rates of HIV infection would be expected for the patients of HCWs who practice in certain settings (e.g., correctional facilities) or in some urban centers with a high prevalence of HIV infection. When feasible, intensive follow-up of these seropositive HCWs and patients, including epidemiologic investigations and laboratory studies, has been undertaken to elucidate possible instances of transmission from HIV-infected HCWs. Because of the inherent limitations in conducting and interpreting retrospective investigations of patients of infected HCWs (11), additional carefully designed and implemented studies are needed to evaluate the small risk for HIV transmission during invasive procedures.


  1. CDC. Update: transmission of HIV infection during invasive dental procedures -- Florida. MMWR 1991;40:377-81.

  2. Ciesielski C, Marianos D, Ou C-Y, et al. Transmission of human immunodeficiency virus in a dental practice. Ann Intern Med 1992;116:798-805.

  3. Ou C-Y, Ciesielski CA, Myers G, et al. Molecular epidemiology of HIV transmission in a dental practice. Science (in press).

  4. Porter JD, Cruikshank JG, Gentle PH, Robinson RG, Gill ON. Management of patients treated by a surgeon with HIV infection (Letter). Lancet 1990;335:113-4.

  5. Armstrong FP, Miner JC, Wolfe WH. Investigation of a health-care worker with symptomatic human immunodeficiency virus infection: an epidemiologic approach. Milit Med 1987;152:414-8.

  6. Mishu B, Schaffner W, Horan JM, Wood LH, Hutcheson R, McNabb P. A surgeon with AIDS: lack of evidence of transmission to patients. JAMA 1990;264:467-70.

  7. Danila RN, MacDonald KL, Rhame FS, et al. A look-back investigation of patients of an HIV-infected physician -- public health implications. N Engl J Med 1991;325:1406-11.

  8. Comer RW, Myers DR, Steadman CD, Carter MJ, Rissing JP, Tedesco FJ. Management considerations for an HIV positive dental student. J Dent Educ 1991;55:187-91.

  9. Hamory BH, Zanotti M, Rohrer VG. HIV ``look-back'' involving an OB/GYN resident (Abstract). In: Abstracts from the second annual meeting of the Society for Hospital Epidemiology of America. West Deptford, New Jersey: Society for Hospital Epidemiology of America, 1992:34.

  10. Dickinson G, Bisno A, Morhart R, Klimas N, Laracuente J. Human immunodeficiency virus infection among patients of a dentist with AIDS (Abstract). Clin Res 1992;40:219A.

  11. Chamberland ME, Bell DM. HIV transmission from health care worker to patient. What is the risk? (Editorial). Ann Intern Med 1992;116:871-3.

  12. CDC. HIV prevalence estimates and AIDS case projections for the United States: report based upon a workshop. MMWR 1990;39(RR-16):1-31.

Use of trade names and commercial sources is for identification only and does not imply endorsement by the U.S. Department of Health and Human Services.

References to non-CDC sites on the Internet are provided as a service to MMWR readers and do not constitute or imply endorsement of these organizations or their programs by CDC or the U.S. Department of Health and Human Services. CDC is not responsible for the content of pages found at these sites. URL addresses listed in MMWR were current as of the date of publication.

All MMWR HTML versions of articles are electronic conversions from typeset documents. This conversion might result in character translation or format errors in the HTML version. Users are referred to the electronic PDF version ( and/or the original MMWR paper copy for printable versions of official text, figures, and tables. An original paper copy of this issue can be obtained from the Superintendent of Documents, U.S. Government Printing Office (GPO), Washington, DC 20402-9371; telephone: (202) 512-1800. Contact GPO for current prices.

**Questions or messages regarding errors in formatting should be addressed to The U.S. Government's Official Web PortalDepartment of Health and Human Services
Centers for Disease Control and Prevention   1600 Clifton Road Atlanta, GA 30329-4027, USA
800-CDC-INFO (800-232-4636) TTY: (888) 232-6348 - Contact CDC–INFO
A-Z Index
  1. A
  2. B
  3. C
  4. D
  5. E
  6. F
  7. G
  8. H
  9. I
  10. J
  11. K
  12. L
  13. M
  14. N
  15. O
  16. P
  17. Q
  18. R
  19. S
  20. T
  21. U
  22. V
  23. W
  24. X
  25. Y
  26. Z
  27. #