In the absence of information and/or the lack of experience
with new microorganisms, laboratory personnel should select
work practices that offer increased protection. Laboratory
manipulations of the Human Immunodeficiency Virus (HIV) have
prompted biosafety committees and safety personnel to take a
hard look at containment practices.
Based upon observations that this virus does not have a documented
aerosol route of exposure, the need to require the additional
containment of a Level 3 facility does not seem critical at
Level 2 facilities used in conjunction with Level 3 procedures
and work practices with the appropriate safety equipment, (safety
centrifuge cups, biosafety cabinets, etc.), affords a greater
margin of safety for personnel than merely increasing facility
This BL2+ containment reduces the risk to laboratory personnel
who are working with infectious agents that are not environmental
hazards. This containment level would also be suitable
for activity with agents where there is insufficient worker
safety information available.
This same approach can be applied to animal experimentation
or production activity as well. Lymphocytic choriomeningitis
virus is a BL2 agent. However, when activities involve
production quantities, potential for aerosolization or working
with infected hamsters, level 3 practices but not necessarily
facilities are recommended. Again, the BL2+ containment
provides the necessary worker protection.
Suitable for work with agents which may cause serious disease.
The suitability of BL-2+ is decided on a case by case basis.
The control of potential biohazards is achieved by strict adherence
to BL-3 practices in a BL-2 facility.