Prevention of Transmission of Blood-Borne Viruses from Medical Staff to Patients
Outbreaks of hepatitis B associated with eAg positive surgeons have been recognized regularly in the UK at the rate of around once a year. This is much higher than that reported for other industrialized countries and could reflect increased vigilance in the UK because of relatively low incidence. The surgeon involved in the majority of outbreaks was thought to be technically competent and had not reported by needlestick injuries. Revised guidelines were issued on HBV infection and health care workers in August 1993. The guidance requires that health care workers who perform "exposure prone procedures" should be vaccinated, that the immune response to the vaccine should be documented, that those with a post-vaccination titre of HBsAb of <10mIU/ml should be investigated further. Those found to be HBsAg and eAg positive should cease to perform exposure prone procedures. Operative procedures are described as exposure prone if there is a risk of injury to the health care worker, which result in the exposure of the patients open tissues to blood or body fluids of the worker. Typically, such procedures include surgical or dental operations in which the workers gloved hands may be in contact with sharp instruments, needles, and sharp tissues inside a patients open body cavity, wound, or confined anatomical space where the hand or fingertips may not be visible at all times.
1. Outbreak Investigation
An outbreak in the UK between 1992 and 1993 where an eAg positive cardiothoracic surgeon was involved in two clusters in two separate hospitals (four cases in the first hospital, and two cases in the second). He was not detected during investigation of the first outbreak because he provided a false specimen. He was only detected following investigation of the second outbreak when the specimens were obtained directly from the surgeon and other health workers involved. The two blood specimens, and a third which he provided earlier to an occupational health department were found to be from different individuals after haptoglobin and alpha-1 antitrypsin grouping. HBV from the six cases proved to be virtually identical to the source surgeon after comparison of the nucleotide sequences and subtyping of HBsAg (all were found to be adr, which was uncommon in the UK).
Patients upon whom the infected surgeon had performed an exposure prone procedure on were identified from hospital operating theatre records. The family doctors of the patients were asked to obtain blood specimens from the patient. A single blood was requested from patients who had been exposed more than 6 months earlier, and two blood specimens (within 3 months of exposure and at least after 6 months after exposure) were obtained from patients exposed more recently. When a patient was found to have serological markers of HBV infection, stored specimens from the patient before surgery were retrieved and tested in parallel. Partners of patients found to be infected were offered serological testing, and, if appropriate, HBV vaccine. Enquiries were made on the presence of any risk factors for HBV infection other than the operation. 18 out of 307 patients tested had serological evidence of recent infection (seroconversion demonstrated or the presence of anti-HbC IgM), of which nine were still HbsAg positive. However one of these patients had a HBV subtype (ayw) which was different from the infected surgeon and thus could not have acquired it from surgery. The other eight had sequences identical or virtually identical with the infected surgeon. Nine patients were determined to have acquired infection acquired at an undetermined time because they were anti-HbC IgM negative and no pre-operative specimen was available. Therefore it could not be ruled that these patients may have acquired HBV infection from surgery. Seven patients were demonstrated to have been infected before surgery. Overall, the rate of transmission to susceptible patients was about 6%.
Tightening of guidelines - as a result of the lessons learnt from the above outbreaks, it is now recommended that when investigating a case of acute hepatitis B in a patient who had undergone surgery in the six months before becoming ill, blood specimens should be obtained from all members of the surgical team even if occupational health records are available. Furthermore, blood specimens from health workers should be obtained by directly observed sampling and tested for HBsAg. Molecular biology techniques may play a useful role in determining the source of infection.
2. Hepatitis B
The introduction of the Department of Health guidelines on HBV infection in health care workers in 1993 led to all health workers undertaking exposure prone procedures being testing for immunity to HBV. Those who were not immune were tested for markers of HBV infection and re-vaccinated if negative. Two trainee surgeons employed by two district general hospitals in the same area were found to be eAg positive HBV carriers. Neither surgeon gave a history of injury at work. The surgeons were suspended from work, counseled, and further blood specimens were taken to confirm the diagnosis and for further investigation. An infection control team, made up of public health physicians, a virologist, a surgeon, and hospital chief executive was convened. The surgeons were examined carefully by the occupational health department to assess the risk of occupational transmission, such as injuries at work, history of jaundice or hepatitis, chronic skin lesions, injecting drug, overseas work, past vaccination, received dental treatment or other operations.
The patient administration system of the hospital was asked to identify all patients that the surgeons had operated on. Patients were counseled individually at home, and blood taken for HBV testing. Patients operated on within 8 weeks earlier were given an accelerated course of vaccine (0, 1, 2, and 12) in the hope that, even if infection had already occurred, severe illness and the development of a carrier state might be prevented. The family doctors of the patients were informed of the management decision and were asked to provide another blood specimen six months after the operation. A press statement was released without giving any personal details about the surgeons or their patients. However it described how long the surgeons had been employed, why they were tested, and at what hospitals the surgeons had worked at. The statement also stated that the surgeons had stopped operating and that all their patients had been counseled. Two of the sixteen patients on whom one of these surgeons had performed exposure prone procedures were shown to have acquired infection from that surgeon. The HBV nucleotide sequences were shown to be identical to the source surgeon by single stranded conforma3tion polymorphism (SSCP). The partners of these patients were also counseled and given HBIG and vaccine.
To date, there has only been a single report concerning the transmission of HIV infection to 5 patients by a Florida dentist. The mechanism of this transmission remains speculative as the dentist died before his techniques could be verified. It is not possible to quantify the risk of transmission from health care worker to patient, but it must be extremely low given that large volumes of blood would need to enter the patients bloodstream. The GMC recommends that all staff who think that they have been at risk of infection should be confidentially tested for HIV infection. Testing for HBV and possibly HCV should also be encouraged. Should HIV infection be detected, counseling and expert advice should be sought. If the health care worker is HIV or eAg positive, then he should stop performing invasive procedures i.e.
Should a health worker who had performed invasive procedure be found to be HIV-positive. Enquiries should be made to determine the possible risk of him having transmitted his infection to patients, such as whether he had sustained any injuries while operating, chronic skin lesions etc. The procedures and the role he played in them should be reviewed. It may be advisable to trace those patients, counsel them and offer anti-HIV testing. Postexposure prophylaxis would not be indicated given the very low risk and also the fact that it is probably ineffective after 36-48 hours.
4. Hepatitis C
Although not as infectious as HBV, there had been reports of HCV infection transmitted from infected surgeon to patient. Although, there are no clear guidelines at present, it is likely, that HCV positive surgeons will be asked to refrain form performing exposure-prone procedures as in the case of HBV and HIV positive surgeons. There are no indications for mass screening of surgeons. Instead, those who are at increased risk should be encouraged to come forward for HCV as well as HIV and HBV testing and counseled if found to be positive.