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Outdoor Pests
West Nile Virus 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 WNV may spread to other areas of the country, and have encouraged
states to increase 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 and blue jays. Thus, dead crows and blue jays have been an important
surveillance mechanism for identifying geographic areas of viral activity.
In response to the request for increased surveillance, The ADH was recently
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 microbiologist 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. All samples will be tested for
WNV, free of charge.
Mosquito Pool Testing - routine collection of mosquitoes for the
purpose of testing for WNV and other arboviruses. Mosquitoes will be sent to the
Arkansas Livestock and Poultry Laboratory for testing.
Mosquitoes are being collected every week by Environmental Specialist from
May 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 and blue jays. Thus, the reporting, collection, and
testing of dead birds have been employed as a surveillance tool for WNV. When a
dead crow or blue jay is found ADH asks that the public bring the dead crows and
blue jays to a local health unit. The local health unit will shipped the dead
birds to the Arkansas Livestock and Poultry Laboratory for testing. Dead crows
and blue jays are the only species collected for testing, but all other species
should be reported.
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