story to find out more.
Artist's rendering of a biting midge (about 2mm
long). The biting midge already is known to transmit several viruses among
livestock and wildlife.
Biting Midge Harbors Livestock Disease Virus
By Rosalie Marion
April 19, 2005
A small, hardy fly called a biting
midge may play an important role in spreading vesicular stomatitis virus (VSV),
which infects cattle, horses and swine, according to Agricultural Research
Service (ARS) microbiologist
VSV causes significant economic losses to the livestock industry from
sickened animals, quarantines and subsequent export/import restrictions.
Drolet, at the ARS
Animal Diseases Research Laboratory in Laramie, Wyo., and colleagues now
have proof that VSV is capable of surviving and spreading throughout the
blood-sucking midge, Culicoides sonorensis. To verify that Culicoides
propagated VSV, the scientists had to find a way to show, without killing the
midge, that virus ingested in a blood meal could survive the insect's midgut,
then replicate and escape from the midgut to infect other organs.
Using an artificial feeding system, Drolet fed midges a viral meal and
tracked the ensuing infections over time to show that VSV infects the midge's
salivary glands and eggs and is shed in the midge's droppings. Drolet used a
genetic technique to verify that the virus is able to replicate within the
more about the research in the April 2005 issue of Agricultural
ARS is the U.S. Department of
Agriculture's chief scientific research agency.