Guidelines for Handling Animal Reservoirs of Hantavirus: Field Research Practices for CSUF
Purpose
These guidelines are based on practices used by Center for
Disease Control personnel in areas known to have fatal human
cases of Hantavirus infection. The guidelines have been modified
for fieldwork in areas of undefined risk. They are intended
to give you information about the best work practices to provide
protection against Hantavirus infection; the purpose of the
document is to give you guidance in your fieldwork. The Office
of Environmental Health and Instructional Safety (EH&IS)
is available to work with you in adapting the guidelines to
your own fieldwork to help you protect yourself. Please contact
EH&IS at extension 7233 if you have comments or suggestions
about the guidelines.
The guidelines will be reissued as additional information
about fieldwork practices and about the epidemiology of Hantavirus
becomes available.
Background
Rodents are the known reservoirs of Hantaviruses, and other
small mammals can be infected as well. In California, deer
mice (Peromyscus maniculatus), which are common throughout
the state, are the implicated reservoir for a strain of Hantavirus
pathogenic to humans. Although current evidence indicates
that the rodents harboring Hantavirus are most prevalent in
rural settings, suburban or urban areas cannot be excluded
as potentially affected.
Infection is believed to result from inhalation, inoculation
through broken skin, or rodent bites. Persons have been infected
after only a few minutes' exposure to laboratory rodents infected
with a similar virus.
People who frequently handle or are exposed to rodents (e.g.,
mammalogists, field biologists, pest-control workers) are
a higher risk for Hantavirus infection than the general public
because the nature of their work brings them into closer and
more frequent contact with rodents and their excretions.
The likelihood of infection with Hantavirus appears to be
low (two confirmed cases in California), but the fatality
rate for the Muerto Canyon (New Mexico) strain is high (approximately
60%). At present, there is no effective vaccine to prevent
infection, and diagnosis and treatment are difficult. Enhanced
precautions are warranted to protect against possible infection.
It is the responsibility of each individual to take appropriate
protective measures. It is the responsibility of the supervisor
to ensure training and access to appropriate protective equipment.
General Practices
- Practice good personal hygiene at all times. Wash your
hands with soap and water or with a disinfectant wipe before
you eat, drink, smoke, or apply lip balm, sunscreen or cosmetics.
- Workers in potentially high-risk settings should receive
a thorough orientation about Hantavirus transmission and
the symptoms of the disease. They should be given detailed
guidance on prevention measures and trained to safely perform
the required activities.
- Workers who develop febrile or respiratory illness within
45 days of a possible exposure should immediately seek medical
attention and inform the examining physician. The physician
should contact local health authorities promptly if Hantavirus-associated
illness is suspected. If appropriate, local health
departments can provide instructions on submitting blood
samples for Hantavirus testing.
- Hantaviruses are lipid-enveloped viruses and are susceptible
to most disinfectants -- dilute hypochlorite solutions (bleach),
70% alcohol, detergents, phenolics, or most general-purpose
household disinfectants. The survival time of the virus
in the environment liquids, aerosols, or dried states is
not known. In the field, carry a spray bottle of disinfectant
or handwipes containing alcohol or detergent.
- Workers should wear rubber, plastic or latex gloves when
handling rodents or traps contaminated by rodent or whenever
the worker has broken skin. Before removing the gloves,
wash gloved hands in a disinfectant and then in soap and
water. Thoroughly wash hands with soap and water after
removing gloves. If this is not possible, then rinse gloves
with water or use a disinfectant wipe; wash your hands thoroughly
at end of the work period.
- Workers may need to wear respirators when handling field-caught
rodents or contaminated traps or when disturbing rodent
burrows and nests. Contact EH&IS for an evaluation
of your work practices and for information on the Respiratory
Protection Program.
Until the infectivity of Hantavirus is better understood,
respirators should be used to minimize exposure to airborne
particles of rodent excreta during procedures that generate
dusts. The proper use of respirators will provide protection
against airborne particles of rodent excreta, which is the
presumed cause of most Hantavirus infections. However,
the incorrect use or care of respirators may increase, rather
than decrease, the risk of exposure to harmful agents.
If fieldwork does not allow respirators to be maintained
in a sanitary condition, or if the conditions of transporting
respirators are such that respirator fit is affected, their
use is not advised. Additionally, respirators must be used
only under the guidance of the Respiratory Protection Program
conducted by EH&IS.
Individual workers should consult EH&IS for an analysis
of their work practices, of exposure risks, and personal
fitness to determine their need for respiratory protection.
The recommended respiratory protection against Hantavirus
is a half-face or full-face air purifying (negative-pressure)
respirator with HEPA filters or equivalent. EH&IS is evaluating other new HEPA -filter masks
as acceptable alternatives.
- Disinfect all traps contaminated by rodent urine or feces.
If this is not done until the end of the trapping run, wear
a respirator whenever handling contaminated traps and transport
empty traps in closed plastic bags.
- In populated areas, dispose of dead rodents by placing
the carcasses in a plastic bag containing enough disinfectant
to thoroughly wet the carcasses. Seal the bag and dispose
of it in the regular trash. Do not overburden the waste
with disinfectant (i.e. allow disinfectant to accumulate
in the bag)
- Workers performing procedures associated with animal body
fluids or creating aerosols by removing organs or obtaining
blood from rodents in an affected area, should contact EH&IS
or the California Department of Health Services for detailed
safety precautions.
- Do not enter enclosed spaces or buildings visibly contaminated
with rodents or rodent droppings. Contact the facility
manager or EH&IS for assistance.
Specific Practices
I. Visual Survey of Aera, Walking, Hiking
No special precautions are needed for protection against
Hantavirus infection. However, respiratory protection may
be advisable in a known affected area that is visually contaminated
by rodents or has especially dusty conditions.
II. Setting Trap Lines
When setting disinfected traps, no special precautions
are needed for protection against Hantavirus. Respiratory
protection is recommended if the traps have not been disinfected
from prior use.
III. Recovery and Transport of Traps Holding Live Animals
Wear protective clothing, including rubber or latex gloves.
If using open-mesh traps, wear respiratory protection. Eye
protection is recommended.
Stand upwind of the trap if possible. Put the trap into
plastic bag that is a least 4 mils thick and large enough
to ensure a sufficient supply of air for the animals. When
transporting animals in an enclosed vehicle to a processing
site, isolate the trapped animals from the passenger compartment
if possible.
IV. Handling Live Animals
Wear protective clothing, including gloves, eye protection
and respiratory protection. Use appropriate methods to provide
protection against both bites and urine contamination of the
hands.
Define a zone to exclude others who are not wearing appropriate
protective equipment. Work with the wind at your back if possible.
Perform all procedures in a manner to minimize the creation
of aerosols and dust.
When possible, anesthetize the animal before handling.
Remove captured animal from the trap by shaking it into an
anesthesia bag; or alternatively, pinch the animal's skin
through the mesh of the trap with forceps and inject it with
anesthetic.
If it is not possible or appropriate to use anesthesia,
wear protective clothing as described and use appropriate
restraining devices. Avoid creating aerosols.
Wearing gloves, disinfect contaminated traps. The ideal
method is to submerge them in a bucket of disinfectant for
10 minutes, rinse twice with water, and set in the sun to
dry. Alternatively, spray the traps with disinfectant. If
traps are not to be disinfected until end of the project,
store them in closed plastic bags.
V. Field Dissection
Field dissection is strongly discouraged. Instead, transport
animals to a laboratory with appropriate containment equipment
in order to process them under safer working conditions.
If field dissection is done, wear protective clothing,
including latex gloves, eye protection, and respiratory protection.
Surgical gowns, shoe covers, and head coverings are recommended.
Process animals in an isolated area. Use the minimum number
of workers to do the job safely. Define and mark a zone to
exclude others not directly involved in the animal dissection.
Work with the wind at your back if possible.
Perform all procedures carefully to minimize the creation
of aerosols. Use extreme caution with any contaminated sharp
items, including needles, syringes, slides, pipettes, capillary
tubes and scalpels. Substitute plastic for glass whenever
possible.
Use hypodermic needles and syringes only for gavage, parenteral
injection, or aspiration of fluids from diaphragm bottles
or well-restrained animals. Use only needle-locking syringes
or disposable syringe-needle units. Do not bend, shear, break,
recap or otherwise manipulate needles by hand before disposal;
place used disposable needles and other sharps in a conveniently
located puncture-resistant biohazardous waste container.
Dispose sharps container as biohazardous waste Place non-disposal
sharps in a hard-walled closable container, containing a suitable
disinfectant. Do not handle broken glassware directly; use
mechanical means such as brush and dustpan, tongs, or forceps.
Place tissues or body fluids in a container that prevents
leakage during collection, handling, processing, storage,
transport, or shipping. Carcasses may be preserved and transported
in 10% formalin, dry ice or liquid nitrogen.
Dispose of unwanted carcasses in a plastic bag containing
enough disinfectant to thoroughly wet the carcasses; seal
the bag and dispose of it in the regular trash.
VI. Clean Up
Place used instruments into disinfectant for 10 minutes,
or autoclave, if possible.
Remove protective clothing, first, then your respirator in
a well-ventilated area (such as outside). Put clothing in
plastic bags for disposal or laundering.
Wash hands thoroughly with soap and water.
VII. Additional Precautions
Establish practical and effective protocols for handling
emergency situations.
VIII. Contact Personnel
EH&IS ext. 7233
Exposure questions and protective measures:
Respiratory Protection Program
Vector Control Service: 714-971-2421
California Department of Health Services: 714-667-3600
Revised: 12/08/2005 SB & SH