Nosocomial transmission of pathogenic organisms has been an unfortunate complication of medical care since the advent of medicine. Until the germ theory of disease was accepted in the latter half of the 19th century, transmission of bacterial pathogens in civilian and military hospitals was one of the biggest risks of coming into contact with a member of our profession. With the advent of aseptic techniques, the risk of bacterial or fungal infection from contaminated equipment has been drastically reduced.
Over the past 50 years, however, concerns about transmission of viral pathogens from medical equipment and supplies have supplanted those related to bacterial infection. Reuse of needles in Egypt in parenteral therapy for schistosomiasis is largely responsible for a 20% seroprevalence rate of hepatitis C virus in the Egyptian blood donor population. HCV was transmitted for many years in the US in the blood supply and, no doubt, on occasion when multi-dose vials were reentered with contaminated needles.
At present HBV, HIV and HCV are the three viral pathogens that are of most concern in the US with respect to improper sterilization of reusable equipment, or in this particular case, the sharing of equipment meant to be used by single patients. The prevalence of these viruses varies among different populations in the US. In general, one would expect that they would be more highly prevalent in people who are in contact with the health care system. In those not on therapy, the titers of virus in blood (and certain other bodily fluids) may be extremely high. Although there is some variation from patient to patient, in general, HBV is present in the highest titers and HIV in the lowest. Other things being equal, transmission of HBV occurs more readily after a parenteral exposure than in the case of the other two viruses.
Proper management of exposures such as the one reported here requires several steps:
- Expeditiously identify and characterize the source patients whenever possible. When source patients are known, it may be possible to characterize the prevalence of potentially transmissible pathogens in the population. Although this is less helpful when it is not possible to link specific source patients to specific patients who have been exposed, general knowledge about the prevalence of potentially transmissible pathogens may be useful in terms of understanding the general risk to the exposed population. When specific source patients can be linked to specific patients that they might have exposed, it is very helpful to know which particular pathogens are of most concern to the exposed patient.
- Contact exposed patients as quickly as possible. In most, but not all, situations it is possible to specifically identify those who may have been exposed. In some situations, however, the ability to identify those at risk is less precise. For example, if failure of sterilizing equipment is noted, it might not be clear how long the equipment was malfunctioning. In cases in which individuals who may have been exposed can be identified, these individuals should be directly contacted and invited for an appropriate medical assessment. In other situations, it might be necessary to make a public announcement about a period of time and characteristics of the populations that might have been exposed and to ask those individuals to contact the health facility involved in the exposure. In addition to identifying those who may have been directly exposed within the health care setting, it is important to be aware that some pathogens may be sexually transmitted and strategies to identify potential secondary exposures should also be developed.
- Counsel and provide appropriate medical surveillance and interventions to those placed at risk by the exposure. When contact with those at risk is made, it is critical that those who are exposed be provided with appropriate one-on-one counseling about their specific risk and that they be provided with easy access to appropriate diagnosis and treatment. Although public health guidelines may be helpful as an initial step in dealing with exposures such as this, the approach to counseling, diagnosis and management will vary from situation to situation. Robust plans for notification, diagnosis and management of those exposed must be developed for each event with the active involvement of physicians and epidemiologists with knowledge about the circumstances surrounding the exposure and about the most contemporary approach to management of the diseases in question. Although involvement of those with expertise in risk management is also critical to the process, their role should be to help operationalize the plans developed by health care professionals rather than vice versa.
It is important to recognize that antiviral therapeutics is a rapidly evolving field. Again, although public health guidelines may be a useful first step in planning the approach to a nosocomial event, public health guidelines have at least two inherent shortcomings
Many months evolve between the time a panel is convened, consensus is attained, guidelines are finally ‘vetted’ by the issuing agency and ultimately published. Furthermore, guidelines may only be periodically updated and it is important to understand how current they are when they are used as the basis for policy development. In a field such as HCV therapeutics which is evolving extremely rapidly as small molecular inhibitors of HCV enter the clinic, guidelines about treatment intervention during acute infection that were devised in PEG-Interferon/ribavirin era are substantially outdated.
Guidelines are consensus documents based on the ‘average’ patient and should always be interpreted and applied in the context of the individual patient in front of the health care professional. In the case of HCV, there are many nuances about the likelihood of clearing acute infection, the likelihood of responding to a specific combination regimen and the selection of treatment regimens for individual patients based on co-morbid conditions that require individual judgment. This can only occur if the response to the exposure event is staffed with people with the appropriate level of medical expertise and if these individuals are provided with the time and resources required to fully evaluate and manage each individual affected by the exposure.
Robert T. Schooley, MD
professor of medicine
Chief in the Division of Infectious Diseases
Academic Vice Chair in the Department of Medicine
The University of San Diego School of Medicine
Disclosures: Schooley is a member of scientific advisory boards for Gilead Sciences, GlobeImmune, Inhibitex, Johnson & Johnson, Monogram Biosciences, and Santaris. He has consulted for Merck.