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Why BSL-4 standards for researchers but not health care workers?

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  • #16
    Re: Why BSL-4 standards for researchers but not health care workers?

    I'm not sure what to make of this - is ebola no longer a BSL-4 pathogen?
    Kortepeter MG, Smith PW, Hewlett A, Cieslak TJ. Caring for Patients With Ebola: A Challenge in Any Care Facility. Ann Intern Med. [Epub ahead of print 16 October 2014] doi:10.7326/M14-2289

    Since the first reported outbreaks of Marburg (1967) and Ebola (1976), there has been an evolution in our thinking about the optimal personal protective measures for medical staff caring for patients infected with these viruses. From 1972 to 2010, a high-level containment care (HLCC) unit at the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), often called ?the slammer,? was considered the gold standard for such care. The unit's engineering controls were modeled after a biosafety level?4 (BSL-4) laboratory, with positive-pressure ?space? suits, compressed in-line air, HEPA filtration, a decontamination shower, ultraviolet light pass boxes, an airlock, and antiseptic dunk tanks for movement of items in and out of the containment area. Toilet waste was discharged into the laboratory sewer system, and the facility possessed its own autoclave, operating room, and bedside laboratory. These built-in capabilities significantly reduced logistics challenges and provided reassurance that nosocomial spread could be reduced to near zero. Given the relatively high percentage of caregivers who have died of filoviral and other BSL-4 virus infections in the field, and the prior uncertainty in whether such high infection rates might be caused by droplet or airborne spread, utilization of such a containment facility seemed reasonable. Although used on occasion to quarantine field workers potentially exposed to highly hazardous viruses, the unit was used primarily for isolating individuals exposed to a BSL-4 virus in the laboratory. During the unit's 38 years of operation, 21 patients were quarantined after potential exposures?and none became ill (3).

    Over time, we learned that the spread of filoviruses occurs primarily by direct contact with blood and body fluids (1). Thus, it was determined that a patient care facility with the full panoply of BSL-4 laboratory?like features was no longer needed. The facility was decommissioned and refurbished as a training facility for scientists working in the institute's containment laboratories...
    Did they decide that no BSL-4 pathogen could ever evolve?

    Ask Congress to Investigate COVID Origins and Government Response to Pandemic.

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    • #17
      Re: Why BSL-4 standards for researchers but not health care workers?

      The difference in requirement for research facilities and hospitals is that research labs are often working with pathogens that are not already present in the community. In that case, accidental release into the community could be the start of an entirely new outbreak.

      In contrast, infection of an HCW from a patient is another new case for a disease already present in the community. In such a case the community will already be prepared, or in the process of preparing to deal with the disease and already aware of the danger.

      It's the same contrast of the seriousness of igniting a fire in a fire hazard area in which there is currently no fire with igniting a fire in an area in which there is already a wildfire burning. In the former situation you have created a very serious problem that was not previously present at all. In the latter case you've exacerbate (probably only very slightly) a situation already present.

      The difference is of little consequence to patients, of course, but to the community it is huge.

      the cost of preventing an event must be related both to the probability of it and the consequences should it occur.