The appearance and spread of West Nile virus (WNV) in North
America has sparked concern among people in the scientific
and public health communities, partly because of the zoonotic
nature of this virus. The possibility of acquiring a zoonotic
disease from handling wildlife is not new; in fact, a number
of diseases are more transmissible to humans while handling
infected animals than WNV. Moreover, the majority of people
infected with WNV either have very mild disease or are completely
unaware of the infection, but the prevalence of WNV in wildlife,
domestic animals, and humans throughout North America, makes
this disease of particular concern to anyone working with animals.
The following guidelines are provided for individuals, particularly
wildlife biologists/researchers, that have field contact
with wild animals that are proven or potential hosts capable
of amplifying and shedding WNV. A list of species found to
be positive is available at:
http://www.nwhc.usgs.gov/research/west_nile/wnvaffected.html.
Currently, all birds should be considered at least potential
hosts capable of amplifying and shedding WNV.
General Considerations -
For people working with wildlife in the field, the primary
concern for becoming
infected with
WNV is through the bite of an infected mosquito.
The recommendations presented here are meant to reduce
the possibility of direct
exposure to a variety of zoonotic diseases.
The methods for direct transmission include (but are not
limited to):
- Inhalation:
inhaling air contaminated with virus contained in body fluids;
splashing of body fluids from infected animals.
- Direct Exposure:
contact from infected animals’ body
fluids to abrasions, cuts in the skin, or mucous membranes
(eyes, mouth).
- Puncture Wounds: cuts from contaminated bones, beaks,
claws, etc; punctures and cuts from contaminated equipment
(needles, scissors, scalpels, etc.)
These general precautions should be taken while handling
all wildlife, especially those that appear sick. Handling
wild animals can increase the opportunity for exposure
to many diseases.
The direct transmission of WNV from infected animal to
biologist outside of the laboratory has not yet been documented,
but enough is known about the nature of WNV to warrant
concern. Fecal material, saliva, and blood are the most
likely sources of virus infection from handling an infected
animal. If you have been in contact with
infected animals or contaminated materials, flush and
wash the exposed area
with soap and water. If you encounter any of the above-mentioned
modes of transmission or if illness develops following
suspected exposure, see a physician as soon as you can
and advise them of your exposure to wild birds and other
wildlife. Symptoms of WNV infection can be found at:
http://www.cdc.gov/ncidod/dvbid/westnile/qa/symptoms.htm
Individuals who may be more susceptible
to WNV infection, or more susceptible to disease following
infection, should take all possible precautions, including
excusing themselves from the work in question. This
group of individuals may include those that are immune
suppressed for any reason (e.g., steroid therapy, chemotherapy,
etc.) and those who have a history of respiratory or
other health problems. Individuals should contact their
physician if they have specific questions or concerns.
Personal Protective Equipment/Procedures -
Depending on the circumstances, some or all of
the personal protective
measures listed here should be used. Personal
protective measures include: using mosquito repellent,
wearing
mosquito resistant clothing (e.g., long pants,
long sleeves, bug jackets, head nets), washing
of hands,
face, and other exposed skin surfaces, using ‘surgical
type’ gloves, wearing coveralls and boots,
wearing eye protection or full face shields, and
wearing face
masks. Measures to reduce exposure to mosquitoes
can be found at:
http://www.cdc.gov/ncidod/dvbid/westnile/qa/prevention.htm
Wildlife-related activities and some
personal protective measures
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Wash hands,
other exposed surfaces
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Coveralls
& Boots
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Gloves
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Eye Protection/
Face Shield
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Face
Mask
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Wildlife Survey |
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Capture/Banding/Tagging |
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Capture & Sample
(aerosol unlikely) |
• |
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[•] |
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Capture & Sample
(aerosol likely) |
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Capture & Sample
(sick animal)
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[•] |
Pickup (dead animal) |
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[•] |
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Pickup (sick animal) |
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[•] |
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Note: Bracketed bullets [•] indicate
that circumstances will dictate the degree of protection
necessary. For example, less precaution may be
necessary if picking up a single dead or sick small
bird, compared
to responding to a die-off of many birds, where
additional precautions would be recommended. “Wildlife
Survey” means
those activities where contact with animals is
minimal, but the opportunity to be bitten by mosquitoes
is
great, such as a walking survey for birds or visiting
wetlands
to count waterfowl. These precautions are suggested
for handling birds only. If invasive procedures,
such as
dissections and
necropsies are planned, more precautions,
including using a tight-sealed forced-air respirator,
are necessary.
Preventing
Further Spread of Disease -
Additional precautions should be considered in
order to prevent the spread of disease while
handling sick
or dead wild animals. Preventive measures include:
-
Wearing gloves while handling animals
and washing hands between each animal;
- Changing gloves or cleaning gloves with a disinfectant
between each animal;
- Changing needles and syringes between blood collection
of different animals;
- Wearing different clothing and footwear at each
activity site and washing/disinfecting clothing/footwear
between sites; and
- Cleaning mist nets, traps, cages, and other equipment
of fecal material, blood, or other materials between
animals and sites.
Some
of these precautions appear obvious while others
may not. Preventing the spread of disease
requires awareness and appropriate behavior, and
is based on common sense.
Precaution
with insect repellents -
Using insect repellent is an effective way to protect
yourself
from WNV and other diseases spread by mosquitoes.
However, certain repellents can cause some harm to
some wildlife
species, particularly amphibians because they
absorb through their skin. Thoroughly wash hands
before handling
any amphibian.
Questions
regarding these handling suggestions can be referred
to Emi Saito at the USGS
National Wildlife
Health Center (esaito@usgs.gov, 608-270-2456).
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