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“The only thing necessary for these diseases to the triumph is for good people and governments to do nothing.”

Investigations of Patients of Health Care Workers Infected with HIV: The Centers for Disease Control and Prevention Database

right arrowLaurie M. Robert; Mary E. Chamberland; Jennifer L. Cleveland; Ruthanne Marcus; Barbara F. Gooch; Pamela U. Srivastava; David H. Culver; Harold W. Jaffe; Donald W. Marianos; Adelisa L. Panlilio; and David M. Bell

1 May 1995 | Volume 122 Issue 9 | Pages 653-657

Objective: To assess the risk for transmission of the human immunodeficiency virus (HIV) from an infected health care worker to patients.

Design: Survey of investigators from health departments, hospitals, and other agencies who had elected to notify patients who had received care from health care workers infected with HIV.

Measurements: Information was collected about infected health care workers, their work practices, their patients' HIV test results, procedures that they did on those of their patients who were tested for HIV, and patient notification procedures.

Results: As of 1 January 1995, information about investigations of 64 health care workers infected with HIV was reported to the Centers for Disease Control and Prevention; HIV test results were available for approximately 22 171 patients of 51 of the 64 health care workers. For 37 of the 51 workers, no seropositive patients were reported among 13 063 patients tested for HIV. For the remaining 14 health care workers, 113 seropositive patients were reported among 9108 patients. Epidemiologic and laboratory follow-up did not show any health care worker to have been a source of HIV for any of the patients tested.

Conclusion: Despite limitations, these data are consistent with previous assessments that state that the risk for transmission of HIV from a health care worker to a patient is very small. These data also support current recommendations that state that retrospective patient notification need not be done routinely.

The risk for transmission of the human immunodeficiency virus (HIV) from a health care worker infected with HIV to patients has not been well quantified. After publication of the reports of the transmission of HIV from an infected dentist to six patients in a Florida dental practice [1, 2], many health departments, hospitals, and other agencies began investigations of health care workers infected with HIV and notified patients who had received care from these workers. In many investigations, the Centers for Disease Control and Prevention (CDC) provided epidemiologic and laboratory assistance. Only a minority of these investigations have been published [3-20]. We summarize the results of all published and unpublished investigations of which the CDC is aware, excluding the investigation of the previously described Florida dental practice [1, 2].


In March 1992, the CDC developed a database to monitor the results of retrospective investigations of health care workers infected with HIV. All of these investigations included the notification of patients, with the exception of the investigations of three U.S. Navy dentists; in these three cases, investigators reviewed the HIV testing records of military personnel treated by the dentists [14]. We surveyed persons responsible for conducting these investigations (such as health department officials, hospital and clinic administrators, and prison officials) to collect information about the infected health care workers, their practices, their patients' HIV test results, the procedures they did on the tested patients, and patient-notification procedures. All of the health care workers had practiced in the United States, except for two who had practiced in the United Kingdom and one who had practiced in Australia.

The scope and comprehensiveness of the investigations varied widely. In a few instances, investigators developed a careful protocol with which to conduct patient notification and follow-up studies. In some situations, officials elected to notify patients but not to offer HIV testing; in others, testing was not well monitored and the number of patients tested could only be approximated. In still other investigations, no data about HIV test results were collected.

Patients were notified if they had been treated during periods that were established by the investigators on the basis of various factors, including the health care worker's medical history, the length of time the health care worker had been in a particular practice, the procedures the health care worker did, and the availability of patient records.


As of 1 January 1995, information was available for 61 health care workers from 24 states, one U.S. territory, and the U.S. Department of Defense; 2 workers from the United Kingdom; and 1 worker from Australia. Eight investigations (13%) began in 1987-1990; 47 (73%) began in 1991; 6 (9%) began in 1992; 2 (3%) began in 1993; and 1 (2%) began in 1994.

Profile of the Health Care Workers Infected with HIV

The 64 health care workers comprised 29 dentists (45%); 4 dental students (6%); 10 surgeons (16%) whose specialties included general, thoracic, breast, trauma, and orthopedic surgery; 4 obstetricians (6%); 12 nonsurgical physicians (19%) specializing in family practice, internal medicine, pediatrics, emergency medicine, or anesthesia; 2 surgical technicians (3%); 1 medical student (2%); 1 dental assistant (2%); and 1 podiatrist (2%). Six of the 64 health care workers were residents or fellows during the period for which the data were collected.

The health care worker's medical condition while providing care to patients was not systematically reported. Eleven health care workers were known to have been asymptomatic while practicing. Three dentists were reportedly mentally impaired while practicing; one family practitioner did procedures with weeping dermatitis of his hands [6].

Patient Notification and Testing Procedures

In 53 of the 64 investigations (83%), decisions about the notification of patients were made in consultation with a review panel. Panels may have included a representative from a state or local health department (74%), a physician specializing in infectious diseases or a hospital epidemiologist (47%), a hospital attorney (28%), a hospital administrator (26%), a health care worker in the same specialty as the worker infected with HIV (28%), the infected worker's personal physician (25%), an infection control practitioner (21%), a dental or medical school dean (19%), and a member of a state licensing board (2%). In 42% of the investigations, other persons, such as faculty members, ethicists, chiefs of staff, and corrections personnel, were included on review panels.

In 14 investigations, patients were notified only if they had had invasive procedures, as defined by the investigators, during the period when the health care worker was thought to have been infected. In 1 investigation, patients were notified only if they had had a procedure done while the health care worker had had a specific medical condition (severe dermatitis of the hand) that may have placed his patients at an increased risk for acquiring HIV [6]. In 41 investigations (64%), patients were notified by letter. Although the media publicized 91% of all investigations, this publicity was the only form of notification in 30% of the investigations. Patients were offered HIV counseling and testing in 55 (86%) of the 64 investigations. Dedicated testing sites or times were established in 39 investigations.

Results of HIV Testing

Results from HIV tests were available for patients of 51 of the 64 health care workers; test results were not collected for the patients of 13 health care workers. None of the patients of these 13 workers identified him- or herself to health officials as being seropositive for HIV.

As of 1 January 1995, approximately 22 171 patients of 51 health care workers had been tested. Tested patients represent 17% of all patients treated by 45 of the 51 health care workers (information not available for 6 workers). For 37 health care workers, no seropositive patients were reported among 13 059 persons tested. Seventeen of these 37 workers were dentists, 4 were dental students, 8 were nonsurgical physicians, 5 were surgeons, 2 were obstetricians, and 1 was a podiatrist. For the remaining 14 workers, 113 seropositive patients were identified among 9108 patients known to have been tested. The number of patients infected with HIV per health care worker ranged from 1 to 41 (Table 1).



Follow-up of Patients Infected with HIV

Epidemiologic and laboratory follow-up has been completed for 110 of the 113 seropositive patients Table 2: Twenty-eight were documented as having been infected before receiving care from the infected health care worker; 62 had established risk factors (as defined by the CDC acquired immunodeficiency syndrome [AIDS] case definition) for acquiring HIV; 15 did not have clearly established risks but had had opportunities for potential exposure to HIV, such as multiple sex partners or exchange of sex for money or drugs; and 5 had no identified risk. Of these 5, 1 had had only a single diagnostic examination by a dentist infected with HIV [7]. The remaining 4 had been treated by a dentist who practiced in an inner-city area with a high prevalence of HIV infection [8].

Genetic sequence analysis was done on HIV strains from three health care workers and 30 of their patients who were seropositive, including 3 of the 5 patients who had no identified risk and 13 of the 15 patients (87%) with potential but undocumented risks for exposure. Sequencing was done by the CDC [7, 8] for all but 1 of the 30 patients [12]. In no instances were the viral strains of patients and health care workers found to be related [7, 8, 12] (Table 2). Sequencing was not done for the remaining seropositive patients because either they or the health care worker had died before a blood sample could be collected, had refused to provide a blood sample, or had been lost to follow-up.

Procedures Done on Patients Tested for HIV

Data about the number and types of procedures done by health care workers were available for 9160 patients from the practices of seven dentists [4, 5, 7, 9, 18], two surgeons [12, 13], two obstetricians, and one family practitioner [6]. Results of HIV tests were available for 4245 (46%) of these patients; these 4245 patients were 19% of all patients with known HIV test results.

Dental Procedures

Three of the seven dentists practiced general dentistry; one specialized in periodontics; one specialized in pediatric dentistry; and two were students. Five of the dentists had AIDS; two were infected with HIV but did not have symptoms. During the period under investigation, these seven dentists treated an estimated 6740 patients. Data on a total of 22 134 procedures were available for 3813 patients; HIV test results were reported for 1826 (48%) of these patients (Table 3). Of the 1826 patients, 21% to 41% had had one or more procedures, such as oral surgery, restorative procedures, or crown and bridge work, that may have required the administration of local anesthetic or that could have caused patient bleeding.



Obstetric and Surgical Procedures

Information on procedures was available for three physicians who did obstetric or gynecologic surgical procedures on a total of 1899 women; HIV test results were known for 832 (44%) of these women (Table 4). One of the physicians was infected with HIV but was asymptomatic; another was symptomatic but did not have AIDS; and the third had an AIDS-defining illness and weeping dermatitis of the hand [6]. In two of the investigations, patients were classified only once into a mutually exclusive listing of procedures; therefore, the total number of procedures done for patients with HIV test results is unknown. Overall, 46% of all women who had had either major gynecologic surgery or vaginal or cesarean deliveries were tested.

Data on procedures have been published for a breast surgeon with AIDS and an orthopedic surgeon infected with HIV [12, 13]. Results of HIV tests were known for 1587 (46%) of the 3448 patients in these two investigations who had had an invasive procedure.


We have summarized the largest existing database on retrospective evaluations of patients who have been treated by health care workers infected with HIV. Excluding the previously described Florida dental practice [1, 2], no cases of transmission of HIV have been documented among approximately 22 171 patients tested. These results are consistent with previous assessments by the CDC, which concluded that the risk for transmission of HIV from a health care worker to a patient during an invasive procedure is very small [21-23].

Our data have important limitations, however, which are due primarily to difficulties in obtaining test results, records, and blood specimens. Results of HIV testing are known for only about 17% of patients who were treated by the infected health care workers during the periods under investigation. Data on procedures are available for only 19% of the patients with known test results; thus, it is not known how many of the remaining patients tested for HIV had had invasive procedures and possible contact with the blood of a health care worker. In most cases, the stage of the health care worker's HIV infection during the time the worker did procedures is not known—for example, it is not often known whether the worker had developed AIDS, the stage of infection at which the titer of HIV in the blood is highest and the risk for transmission might be increased [24, 25]. Finally, even a study population of 22 171 patients might lack sufficient statistical power to detect a low-frequency event, especially if, as seems likely, the risk for transmission is greatest for only a subset of health care workers or procedures [21, 22, 26]. In view of the great heterogeneity of procedures and health care workers summarized here, we have refrained from using these data to calculate numerical estimates of the mean or confidence intervals for the risk for transmission of HIV from workers to patients, either collectively or for individual specialties. These limitations notwithstanding, it seems likely that if HIV were easily transmitted from health care worker to patient, evidence of such transmission would have been detected in these investigations, particularly in situations in which a health care worker's altered mental status or breach of infection control practices was noted [6, 8].

Many of these retrospective investigations involved intensive effort and the expenditure of substantial resources by hospitals, state and local health departments, and the CDC [6, 12, 13]. Failure to find additional instances of transmission to patients supports recommendations by the CDC and others that state that retrospective patient notification need not be done routinely, but should be considered on a case-by-case basis, taking into account an assessment of risks, confidentiality issues, and available resources [6, 21, 26, 27].

Author and Article Information

From the National Center for Infectious Diseases and the National Center for Preventive Services of the Centers for Disease Control and Prevention, Atlanta, Georgia.
Requests for Reprints: Laurie M. Robert, MS, Hospital Infections Program, Mailstop E-68, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA 30333.
Acknowledgments: The authors thank Robert Comer, Nancy Bringman Taylor, Audrey Smith Rogers, Paul Arnow, Russell Martin, William Wolverton, Paul Silverman, Richard Danila, Robert Scott, Jenice Longfield, Kevin Gipson, William Hall, Bob Greenlee, Kim Callanan, R. Lynn Browder, Bobby Jones, Gordon Dickinson, Don Conner, Rebecca Meriwether, M. Geoffrey Smith, Patricia Checko, Mary Lou Fleissner, Sean Flood, Perry Smith, Calvin Linnemann Jr., Karen Chapman, Harold Laswell, Stacey Bourgeois, Michael Heuer, Georgia Thomas, Ban Mishu Allos, Mark Miller, Karen Smalley, Ronald Altman, Rick Reich, James Cottone, John Weston, Beverly Dahan, Bryan Bartlett, Reginald Finger, Patricia Starr, Karen Adams, Shirley Crawshaw, Mark Bek, Kholoud Porter and Jeff Jones for supplying data; Penny McKibben for assistance with data management; and Sara Critchley for assistance with tables. Data from investigations in the United Kingdom and Australia were provided by the Communicable Disease Surveillance Centre, London, and Sydney and New South Wales health authorities.


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