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WNV
Surveillance in Arkansas
The summer
of 1999, West Nile Virus, a mosquito-borne disease never before
reported in the Western hemisphere, caused encephalitis in
62 people and numerous horses in the New York City and Long
Island area. There were seven human and over 10 equine deaths.
Birds are the natural hosts for the virus, which can be transmitted
from infected birds to humans and other animals through the
bites of infected mosquitoes. Scientists and public health
officials are concerned with the spread to other areas of the
country, and have encouraged states to continue ongoing surveillance
activities for WNV and other arboviruses. Since birds are
the natural host for WNV, an unusual characteristic noted
for WNV is that it causes high mortality among infected birds,
especially crows, blue jays, robins, hawks and owls. Thus, these birds have been an important surveillance mechanism for identifying
geographic areas of viral activity.
In response
to the request for increased surveillance, The ADH was awarded a substantial grant from the CDC to enhance WNV and
other arbovirus surveillance. Surveillance activities will
include but not be limited to the following:
HUMAN
TESTING
- The ADH has purchased the lab equipment necessary to perform
human arbovirus testing at the ADH Laboratory. All human samples
will be tested for West Nile Virus, St. Louis Encephalitis,
and Eastern Equine Encephalitis free of charge. Serum is the
specimen of choice, but cerebral spinal fluid can be tested
as well. One of our microbiologists was sent to the arboviral
division of the CDC in Ft. Collins to receive expert training
in arboviral testing. All clinicians within the state have
been encouraged to send samples from suspect encephalitis,
meningoencephalitis, or meningitis cases to the ADH to help
obtain an appropriate diagnosis. Clinicians were alerted ADH's
testing capacity using newsletters.
EQUINE
TESTING
- Veterinarians have also been encouraged to send serum samples
to the Arkansas Livestock and Poultry Laboratory for equine
cases of encephalitis, meningoencephalitis, or meningitis.
MOSQUITO
POOL TESTING
- ADH will collect mosquitoes for the purpose of testing
for WNV and other arboviruses.
Mosquitoes are being collected every week by Environmental
Specialist from June through October. Collections are being
conducted in numerous counties throughout the state. In the
event there are reasons to suspect arboviral activity in any
region of the state, that area will be targeted for enhanced
mosquito collection and testing.
DEAD
BIRD SURVEILLANCE
- Certain bird species are highly susceptible to WNV, especially
crows, blue jays, robins, hawks and owls. Thus, the reporting, collection, and
testing of dead birds have been employed as a surveillance
tool for WNV. When one of these dead birds is found, ADH asks
that the public bring it to the local
health unit. The local health unit will ship the dead bird
to the ADH Laboratory for testing.
Dead crows, blue jays, robins, hawks and owls are the only species collected for
testing, but all other species should be reported.
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