Exposures to Agents in BSL-3 and BSL-4 | CDC EID

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Volume 16, Number 3–March 2010
Perspective
Preparing a Community Hospital to Manage Work-related Exposures to Infectious Agents in BioSafety Level 3 and 4 Laboratories
George F. Risi, Marshall E. Bloom, Nancy P. Hoe, Thomas Arminio, Paul Carlson, Tamara Powers, Heinz Feldmann, and Deborah Wilson
Author affiliations: Infectious Disease Specialists, PC, Missoula, Montana, USA (G.F. Risi); St. Patrick Hospital and Health Sciences Center, Missoula (T. Powers); National Institutes of Health, Bethesda, Maryland, USA (G.F. Risi, N.P. Hoe, T. Arminio, P. Carlson, D. Wilson); and Rocky Mountain Laboratories, Hamilton, Montana, USA (M.E. Bloom, H. Feldmann)
Suggested citation for this article

Abstract
Construction of new BioSafety Level (BSL) 3 and 4 laboratories has raised concerns regarding provision of care to exposed workers because of healthcare worker (HCW) unfamiliarity with precautions required. When the National Institutes of Health began construction of a new BSL-4 laboratory in Hamilton, Montana, USA, in 2005, they contracted with St. Patrick Hospital in Missoula, Montana, for care of those exposed. A care and isolation unit is described. We developed a training program for HCWs that emphasized the optimal use of barrier precautions and used pathogen-specific modules and simulations with mannequins and fluorescent liquids that represented infectious body fluids. The facility and training led to increased willingness among HCWs to care for patients with all types of communicable diseases. This model may be useful for other hospitals, whether they support a BSL-4 facility, are in the proximity of a BSL-3 facility, or are interested in upgrading their facilities to prepare for exotic and novel infectious diseases.
Over the past decade, biomedical research performed on agents of viral hemorrhagic fevers (VHFs) has substantially increased. These agents are members of several virus groups, including filoviruses (Ebola virus, Marburg virus), Old World arenaviruses (Lassa virus, Lujo virus), New World arenaviruses (Machupo virus, Junin virus, Sabia virus, Guanarito virus, Chapare virus), flaviviruses (Omsk hemorrhagic fever virus, Kyasanur Forest disease virus), and bunyaviruses (Crimean–Congo hemorrhagic fever virus, Rift Valley fever virus) (1). Work with these agents is performed in specialized containment laboratories, operating at either BioSafety Level (BSL) 3 or BSL-4. BSL-3 denotes the potential for aerosol transmission to the laboratory worker. An agent that also is associated with high lethality and for which no available vaccine or specific treatment exists is studied at BSL-4 (2). Many VHF agents have a demonstrated potential for person-to-person transmission, including in nosocomial settings. A recent example of person-to-person transmission to hospital personnel occurred in September and October 2008 when Lujo virus was transmitted from the index patient to a paramedic, 2 nurses, and a member of the janitorial staff. Barrier precautions were not in place at the time of these events (3).

To provide safe work settings in which to study these pathogens, several BSL-4 laboratories are either in operation or under construction in the United States and abroad (Table 1) (T.G. Ksiazek, pers. comm.). Operation and management of these facilities are characterized by redundant engineering of safety features, strict administrative oversight, biosecurity measures, and extensive training (2,4), all designed to reduce the risk for exposure to persons working in this environment and prevent agents from being released into the community. Despite these safeguards, researchers in the United States and abroad have, on occasion, sustained occupational exposures to such agents, which rarely have resulted in overt illness and death (Table 2) (5–11). Because of the potential for person-to-person transmission of many VHF agents, rendering care to exposed or ill persons requires considerations beyond the scope of traditional hospital practices. Contact and/or airborne isolation guidelines may need to be added to standard isolation over the course of a patient's hospitalization (12,13).

On several occasions, persons naturally infected with a VHF agent have sought treatment at hospitals located in industrialized areas of the world (14–21). Often the correct diagnosis is not considered at the time of hospitalization, and only standard isolation is used until such time as the diagnosis is suspected or confirmed. Despite this limitation, nosocomial transmission of these agents is uncommon in adequately resourced hospitals (16,18,20,21). Notably, the medical care requirements for patients with a naturally acquired VHF illness are identical to those needed for laboratory-acquired infections with the same agents.

Because of the limited and unique settings in which BSL-4 research has historically taken place in the United States, hospitalization for occupational exposures to VHF agents has typically been a dedicated facility remote from a conventional hospital, e.g., the medical containment suite (the 'slammer') at the US Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, Maryland, USA, or the biocontainment patient care unit at Emory University, Atlanta, Georgia, USA. The benefits of a remote facility include reducing the risk for nosocomial transmission, use of personnel who are already trained in managing a patient in containment, and control of public access (22). However, this approach has several serious drawbacks, including limited access to medical specialties and nursing staff, limited availability of medications and blood products, and limited access to specialized equipment such as ventilators and hemodialysis machines. In addition, increased psychological stress is experienced by patients confined to such a facility. Finally, given that the need to activate these facilities is extremely rare, the expense of building and maintaining a stand-alone unit poses a substantial limitation to this approach.

In addition to physical separation of the facility, medical and support staff at the USAMRIID facility work in positive pressure suits similar to those used in the laboratories themselves (22). Although the use of such suits provides protection to the caregiver, positive pressure suits are cumbersome, physically demanding to work in, and require substantial time for donning and doffing (dressing and undressing). Furthermore, venipuncture and other interventions in this unaccustomed and inconvenient setting pose a clear exposure risk to healthcare workers (HCWs). These factors are serious drawbacks when a HCW needs to render care to an acutely ill patient.

Documented clinical experience from several situations clearly indicates that nosocomial transmission can be prevented by implementing standard, contact, and airborne isolation procedures (3,15,16,19,20). Furthermore, all BSL-4 research programs stress the importance of recognizing and quickly reporting potential work-related exposures and illnesses to occupational medical and safety staff. Thus, healthcare staff will typically be informed about the specific agent and the nature of the exposure early in the incubation period. This will enable rapid evaluation and timely institution of appropriate isolation precautions.

Given all these considerations, what additional enhancements are really necessary for a hospital to safely care for patients while still enabling delivery of optimum medical care? Because of sensational misconceptions about VHF agents in popular media such as movies and the press, other serious issues are the willingness of HCWs to render care to such persons and how to determine what additional actions would increase the likelihood of their doing so. We offer a practical approach to dealing with these issues in the procedures followed by a patient isolation facility located in Missoula, Montana, USA, and its attendant training and educational components.

Care and Isolation Unit
The Division of Intramural Research of the National Institute of Allergy and Infectious Diseases (NIAID) recently completed construction of an integrated research facility with BSL-4 research space at its Rocky Mountain Laboratories (RML) in Hamilton, Montana. As part of the project, NIAID contracted with St. Patrick Hospital and Health Sciences Center (SPH), a regional referral medical center located in Missoula, Montana, for provision and staffing of a patient isolation facility to support the RML BSL-4 research program. The facility, known as a care and isolation unit (CIU) (23) was designed to care for RML workers who had either known or had potential exposure to, or illness from, work-related diseases. The facility had to be located within 75 miles of RML, had to provide the full range of standard in-patient care, including intensive care, and had to meet the facility design guidelines of the National Institutes of Health, Division of Occupational Health and Safety (NIH DOHS) (24). Furthermore, the hospital had to supply the personnel to provide the full range of medical and nursing care and to be able to accept a patient within 8 hours (this would entail notification of key members of the hospital hierarchy, transferring patients if the rooms were currently occupied, securing adequate nursing and support staff, and carrying out systems checks to ensure that air handling systems and autoclaves were operational). In addition to the physical facility, a training program for critical care nurses, physicians, and other medical personnel was a major component of the contract.

To satisfy the NIH requirements for the CIU, the following elements were needed: 1) access control, i.e., the ability to restrict entrance into the CIU to authorized persons only; 2) three separate stand-alone rooms, each with a bathroom and shower, separate air handling, and an anteroom separating the patient room from the hallway; 3) directional air flow from the hallway into the anteroom and from the anteroom into the patient room; 4) a dedicated exhaust system providing >12 air exchanges per hour to the patient rooms (including >2 outside air changes per hour); 5) passage of exhaust through a HEPA filter to the building exterior >8 feet above the rooftop and well removed from air intake ducts; 6) room surfaces constructed of seamless materials amenable to topical disinfection; 7) the capability for the full range of intensive care unit (ICU) monitoring and support, including the ability to perform limited surgery, hemodialysis or peritoneal dialysis, Swan-Ganz catheter placement, and hemodynamic monitoring; and 8) a separate autoclave within the CIU for sterilizing all items that come out of a patient room.

SPH was selected to provide these services and facilities. SPH is a not-for-profit medical center under the sponsorship of the Sisters of Providence. It has 195 acute care beds, and >10,000 patient admissions per year. The full range of standard specialty medical care is available within the hospital, including 24 hour, 7 day/week availability of specialists in critical care, infectious disease, and all surgical subspecialties.

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Suggested Citation for this Article
Risi GF, Bloom ME, Hoe NP, Arminio T, Carlson P, Powers T, et al. Preparing a community hospital to manage work-related exposures to infectious agents in BioSafety Level 3 and 4 laboratories. Emerg Infect Dis [serial on the Internet]. 2010 Mar [date cited]. http://www.cdc.gov/EID/content/16/3/373.htm

DOI: 10.3201/eid1603.091485