Institutional
Animal Care and Use Committee
ZOONOTIC DISEASES
(Text Modified from Document Created
by Michael S. Rand, DVM, ACLAM)
Institutional Policies and Procedures
Introduction
Table 1 should alert investigators working
with these animals of the potential for inadvertent introduction of zoonotic
diseases into animal colonies, causing possible disease exposure and infection
in laboratory workers. Preventing laboratory acquired infections requires
a five-pronged approach, including: appropriate engineering controls; appropriate
quarantine and stabilization of the animal; appropriate work practices
and procedures (including supervisory control); appropriate personal protective
devices; and training. This approach is especially important in preventing
clinically silent laboratory acquired infections, such as Lymphocytic Choriomeningitis
Virus or Herpesvirus B in animals. The universal precautions approach used
when manipulating human blood or blood products offers an analogous situation:
staff members should follow safe work practices rigorously whenever working
with (zoonotic) agents that may not induce signs of ill health in the animal.
Infection
Control in the Laboratory and Animal Facility
Since zoonotic diseases can enter the
body through a variety of methods including broken skin or through the
eyes, mucus membranes, or the lungs, a combination of engineering controls,
work practices, and personal protective devices are necessary to prevent
laboratory acquired infection.
Engineering
Controls
Of these routes of entry, controlling
transmission by the aerosol route is the most difficult. The facility (laboratory,
procedure, or animal room) must operate with inward directional air flow;
i.e., air must move from the corridor (area of least contamination) into
the room where staff members manipulate the animal or animal by-products
(area of greatest contamination). Air exhausted from these rooms cannot
be recirculated to other rooms; the air must be discharged to the outside.
When there is a very high potential for aerosol generation, additional
facility related engineering controls such as sealed penetrations through
the walls, double door access to the rooms, or installation of HEPA filters
in the exhaust air system may be necessary. A facility can also apply engineering
controls locally to reduce aerosol spread. Containment devices (e.g., bonnet
tops for cages, ventilated racks) will help keep a potential zoonotic agent
in the cage. Staff should use biological safety cabinets when opening the
cages, conducting sampling or necropsy activities, or manipulating infectious
materials. All biological safety cabinets and the high efficiency particulate
air (HEPA) filters in ventilated cage racks need to be certified and leak
tested annually. Staff should use special devices such as sealable centrifuge
cups, blenders, or homogenizers whenever there is a high potential for
creating aerosols of infectious microorganisms. Workers must also rely
on personal protective devices, such as respirators, to minimize their
exposure to infectious aerosols when containment devices offer insufficient
protection.
Animal Quarantine
and Stabilization
Quarantine is the separation of newly
received animals from those already in the facility until the health of
the animal has been evaluated. Effective quarantine minimizes the introduction
of disease agents into established colonies. The quarantine period should
be of sufficient duration to allow expression of diseases present in the
incubation stages. Some or all of the following should be achieved during
the quarantine and stabilization period: diagnosis, control, prevention,
and treatment of diseases; physiological and nutritional stabilization;
and, grooming to include ectoparasite control (many zoonotic agents require
an arthropod vector!).
Work Practices and
Procedures
Handwashing is an important means of preventing
the spread of infectious contaminant. Workers should wash their hands after
removing gloves and before leaving the laboratory, procedure room, or animal
room. A handwashing sink should be located near the door of the room. Liquid
soap dispensers are preferable to soap bars to minimize cross contamination.
After thorough washing, workers should dry their hands with disposable
paper towels. Eating, drinking, smoking, handling contact lenses, and applying
cosmetics should not be permitted in laboratories, nor should any other
activities that might involve hand-to-mouth or hand-to-eye contact, such
as mouth pipetting. Staff members should perform all manipulations of potentially
infectious materials so as to minimize aerosol production. The person who
generates infectious waste or contaminates equipment, work surfaces, or
other areas is responsible for decontamination before the next person begins
work. Chemical disinfection or, preferably, steam autoclaving, is recommended
for decontaminating reusable materials before washing. When finished working,
staff members must dispose of contaminated waste materials, and package
them according to local infectious waste regulations prior to disposal.
Personal Protective
Devices
Staff members can protect against splashes
and splatters by adhering to careful work practices and rigorous use of
personal protective devices. Face shields provide protection for eye and
mucus membranes. Biological safety cabinets provide near sterile work environments
that offer protection to the worker, the materials they are manipulating,
and the work area itself. Lab coats or work uniforms will help prevent
contamination of street clothes and should be changed whenever visibly
soiled. Staff members should autoclave lab coats before disposal or laundering;
soiled labcoats should go to on site or professional cleaners only. Latex
or vinyl gloves provide barrier protection for hands. Staff must change
gloves that are torn or visibly contaminated, and should autoclave them
before disposal. Gloves and other protective devices cannot prevent needle
sticks or other unintentional injuries caused by sharp instruments, broken
glass, etc. Self sheathing needles are available, as are other engineered
safety devices. Needles must not be bent, cut, or recapped: they must be
discarded directly into puncture resistant and leakproof containers.
Training
All at-risk persons working in a facility
should receive appropriate training on that facility's particular biohazards,
precautions, and biohazard evaluation procedures. Personnel should receive
annual updates and additional training when procedures or policies change.
Laboratory workers and animal care personnel should know how to recognize
hazard warning signs, to protect themselves and their coworkers against
each hazard, and to react properly in the event of emergencies, such as
an unintentional biohazard material release. Training should be appropriate
for the employee's education, experience, and language skills, and should
be performance based to ensure that employees master the skills before
encountering a hazard. The facility should incorporate the syllabus of
the training programs into its safety manual. Supervisors should assess
each employee's biosafety knowledge during the formal training period and
later through subsequent regular observation of routine activities. All
persons who work in a laboratory bear responsibility to minimize risk of
infection through consistent good safe microbiological practices and procedure.
Role of the Facility
Director
The facility director may be the veterinarian,
researcher, facility manager, or other individual responsible for day-to-day
operations and the occupational health and safety of facility employees.
Laboratories working with infectious human disease agents should elect
a director who is knowledgeable and experienced in laboratory microbiology;
this becomes increasingly important when staff are conducting work at BSL3
and BSL4. The facility director is responsible for ensuring that all employees
have appropriate training regarding potential laboratory hazards such as
chemicals, radioactive materials, and infectious microorganisms. The director
must establish and maintain appropriate biosafety level practices and procedures
in the laboratory or animal facility; and, it is incumbent on the director
to ensure necessary biosafety materials and equipment are available to
all personnel. To maintain facility safety, the director should review
the research protocols and, based on the anticipated risks and necessary
precautions, limit access to the laboratory or animal facility to those
persons who have been advised of these potential risks. In general, immunocompromised
persons or those for whom infection might be unusually hazardous should
not have access to the animal room. Furthermore, the director should establish
policies or specific requirements necessary for worker health and safety.
In conjunction with occupational health personnel, the director can establish
medical surveillance programs for staff members who plan to work with specific
microorganisms. The facility may collect employee serum samples periodically
and store them for subsequent testing under strict monitoring by appropriate
management control to guarantee confidentiality and informed consent. The
director should ensure that the laboratory and animal rooms are posted
with hazard warning signs incorporating the universal biohazard symbol,
listing the names of the microorganisms in use, the personal protective
equipment to be worn in the room, special required practices and the names
and phone numbers of persons to contact in case of emergency. Staff members
should immediately report unintentional exposures to infectious materials
to the supervisor or director, who will arrange for medical evaluation,
treatment, and subsequent surveillance as needed. At-risk personnel should
inform supervisors of any febrile illness as part of ongoing surveillance
for potential laboratory associated infections. In addition, the director
should maintain appropriate written records of all unintentional releases,
spills, and exposures to biohazardous materials. The laboratory director
should also make sure that an appropriate detailed biosafety manual, incorporating
established guidelines as minimum standards for handling injuries, spill
cleanup, waste handling, etc., is developed for the facility. This manual
can then become part of the overall employee occupational safety and health
program and a basis for on-the-job training activities. Granting agencies
and regulatory organizations (OSHA, APHIS, AAALAC) which inspect animal
facilities often request such manuals.
Conclusions
To prevent laboratory acquired infections,
laboratory and animal care workers must carefully follow published explicit
biosafety guidelines and must be cognizant of special biosafety hazards
posed and animal husbandry practices needed by animals. Staff members should
perform any animal work with infected materials (e.g., clinical specimens,
tissues, tumor cell lines) at ABSL-3. Propagation of tumor cell lines in
animals, especially in immunocompromised animals, requires particular biosafety
vigilance, including quarantine of newly acquired animals, screening of
cell lines and animals from nonstandard sources for extraneous infections,
regular sentinel surveillance of laboratory animals, and preventing feral
or wild animal access to the animal facility. In addition, laboratory personnel
must be aware of the potential for extraneous infections in the laboratory,
and how such infections would present in workers, animals, and cell lines.
Any facility engaged in animal passage of cell lines not carefully tested
for various microorganisms such as arenavirus or hantavirus should reevaluate
their extraneous microbiological monitoring programs and insist on rigorous
adherence to appropriate engineering controls, work practices, and procedures
to prevent similar outbreaks.
References
Collins, CH. 1993. Laboratory-Acquired
Infections. Elsevier Publishers, Boston, MA.
Chomme, BB. 1992. Zoonoses of house
pets other than dogs, cats, and birds. The Pediatric Infectious Disease
Journal. 11(6):479-87.
Cooper, JE. 1977. Diseases of lower
vertebrates and biomedical research. Laboratory Animals. 11(2):119-23.
Guide for the Care and Use of Laboratory
Animals. 1985. National Institutes of Health, Bethesda, MD.
Fox JG and NS Lipman. 1991. Infections
transmitted by large and small laboratory animals. Infectious Disease Clinics
of North America. 5(1):131-63.
Hubbert, WT, WF McCulloch, and PR Schnurrenberger.
1975. Diseases Transmitted From Animals to Man. Charles C. Thomas Publishers,
Springfield, IL. Richmond, JY, CA Dykewicz, LM Aldeman, et al. Working
safely with LCMV-infected immunocompromised animals. Lab Animal. May, 1994:25-28.
Schlossberg, D. 1994. Infections of
Leisure. Springer-Verlag, New York, NY.
Telford, SR, RJ Pollack, and A Spielman.
1991. Emerging vector-borne infections. Infectious Disease Clinics of North
America. 5(1):7-17.
Disease
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Pisces
Reptilia
Amphibia
Aves
Marsupialia
Insectivora
Chiroptera
Rodentia
Cetacea
Carnivora
Artiodactyla
Xenarthra
Lagomorpha
Primates
Disease
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Bacterial Diseases
Rickettsial Diseases
Fungal Infections
Viral Diseases
Bites and Scratches
Allergic Sensitivities
Arthropod Infestations
Protozoan Diseases
Nematode Zoonoses
Cestode Zoonoses
Trematode Zoonosis