Patient-to-patient transmission of bloodborne viruses via contaminated medical equipment in hospital environments is well-documented. Transmission usually involves violation of a standard precautions tenet or inadequately sterilized items. Blood and saliva are present during dental treatment and provide an opportunity for the transmission of bloodborne pathogens.
The spread of disease can occur through direct contact with body fluids (contact with nonintact skin or mucous membranes), or through indirect contact with contaminated instruments, equipment, and appliances. An example of this would be a needlestick accident. However, to date, there have been no published reports of a patient acquiring a blood pathogen infection from reusable dental instruments used on another patient.
A recent article reported on events associated with a dentist’s admission of the periodic use of unsterilized, reusable patient-care items. In September 2000, public health officials in Glasgow, Scotland, were notified by a person diagnosed with hepatitis C virus (HCV) after donating blood. The woman wanted to know how she contracted the infection. She reported no recognized risk factors for HCV, except possibly for dental treatment in a local practice from 1989 through 1995.
From 1984 through 1988, her dentist worked under close supervision as an associate in several area practices. There were no concerns about his performance. In 1989, he bought a practice, and worked there until 1994 when he went on a prolonged sick leave. In 1997, he was removed from the UK Dentists’ Register following charges of serious professional misconduct. This included fraudulent payment submission to the National Health Service (NHS). In January 2001, the dentist pleaded guilty to fraud and reckless conduct for exposing his former patients to infection and possible disease by repeatedly using unsterilized equipment on successive patients from 1992 to 1994.
Glasgow public health officials decided that all patients should be notified of the incident, and be offered testing for the human immunodeficiency virus (HIV), hepatitis B virus (HBV), and HCV. Because the dentist had destroyed his practice’s clinical records, the extent of individual risk was impossible to determine. A list of patients was generated from the names of all people making claims against NHS dental coverage. Those treated by the dentist were sorted from the list.
NHS payments for services were authorized for 4,689 patients in the practice between 1990 and 1994. Of these, 3,804 were matched to names and addresses on the local Community Health Index. More than 80 percent had a current address in the Greater Glasgow health board area. Of these, 397 could not be found by mail, or claimed that they had not been treated. Seven persons who were not sent letters came forward, claiming to have been treated by the dentist.
In total, 1,696 people requested an appointment; however, only 1,057 kept appointments. Of these, 1,005 were counseled and then serologically screened for HIV, HBV, and HCV. Results were obtained from an additional 132 patients who were tested by their own physicians, or in a clinic outside the Glasgow area.
None of the patients tested were positive for HIV. One patient showed evidence of a previous HBV infection while 13 had antibodies against HCV. Molecular investigation of the index case indicated a genotype 3 HCV. The other cases were split between genotype 1a and 1b. No significant genetic relatedness was indicated among the isolates. All viral strains were common to the Glasgow area.
The patient-notification scheme used was not the result of either an acute seroconversion illness, or the identification of an infected healthcare worker. Rather it was the result of an admission in a court of law of the failure to sterilize dental instruments between patients. The investigation found no evidence of patient-to-patient transmission of a bloodborne pathogen; however, less than 25 percent of patients treated in the practice were eventually screened. Disease transmission among other patients could not be excluded; however, the prevalence rate of HCV within the patient pool tested was similar (1.1 percent) to that of the Greater Glasgow area. Of the 13 cases of HCV infection, eight showed evidence of active infection.
OSAP, the Organization for Safety & Asepsis Procedures, is dentistry’s prime source for evidence-based information on infection control and prevention, and human safety and health. More information regarding instrument sterilization and the transmission of HIV, HBV, and HCV is available on the OSAP Web site at www.osap.org.
Dr. Charles John Palenik is an assistant director of Infection Control Research and Services at the Indiana University School of Dentistry. Dr. Palenik is the co-author of the popular “Infection Control and Management of Hazardous Materials for the Dental Team.” He serves on the Executive Board of OSAP. Questions about this article or any infection-control issue may be directed to [email protected].