Reasonable Rascal
09-25-02, 23:11
WEST NILE VIRUS, HIPPOBOSCID FLIES - USA (PA)
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A ProMED-mail post
Date: Tue 24 Sep 2002
From: John P. Maher
Louse Flies (_Hippoboscidae_) Test Positive for West Nile Virus
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A pool of Hippoboscid flies has tested positive for West Nile virus in Dauphin Co (Pennsylvania). These flies are also called louse flies and are ectoparasites on birds and mammals. We have no idea regarding the importance of these insects because no work has been done with respect to Hippoboscid vector competence for West Nile virus. If they are capable of vectoring West Nile virus, they could be very important enzootic vectors in the wild in roosting areas and among nest mates. Birds in captivity, such as those in zoos and bird rehab centers, could also be disproportionately affected. The flies were collected from a symptomatic Great horned owl.
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John P. Maher
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[2]
Date: 25 Sep 2002
From: Hutchinson, Michael <mhutchinso@state.pa.us>
[In response to a query for additional information on the identification of West Nile virus in hippoboscidae, Michael Hutchinson was kind enough to send the following. - Mod.MPP]
Thank you for your question about the positive louse flies. We have sent 3 pools of Hippoboscidae for West Nile virus testing. The first pool of 5-6 specimens was taken from a Red Tail (RT) hawk that tested positive for WN - that pool tested negative. The second pool contained 5 specimens that were collected from a symptomatic Great Horned (GH) owl. That is the pool that tested positive through PCR as well as through virus isolation, indicated the presence of live virus. This is not surprising in that the specimens were visibly blooded. The results from a 3rd pool of non-blooded specimens are still pending. Future submissions of Hippoboscids from symptomatic birds will be held in the lab for 7-10 days to try to ensure complete digestion of the blood meal. Positive results from non-blooded insects will give us a better idea if the virus can survive within the louse flies. We will still be in need of vector competency studies to nail down the importance, or lack thereof, of this group. As for the question about the identity if the flies, they are in the genus Icosta and I'm waiting on literature to provide a species level identification. There are about 8 species in North America and they are bird biters.
Michael L. Hutchinson
Biologist - West Nile Virus Program
PA Department of Environmental Protection
*******************************************
A ProMED-mail post
Date: Tue 24 Sep 2002
From: John P. Maher
Louse Flies (_Hippoboscidae_) Test Positive for West Nile Virus
--------------------------------------------------
A pool of Hippoboscid flies has tested positive for West Nile virus in Dauphin Co (Pennsylvania). These flies are also called louse flies and are ectoparasites on birds and mammals. We have no idea regarding the importance of these insects because no work has been done with respect to Hippoboscid vector competence for West Nile virus. If they are capable of vectoring West Nile virus, they could be very important enzootic vectors in the wild in roosting areas and among nest mates. Birds in captivity, such as those in zoos and bird rehab centers, could also be disproportionately affected. The flies were collected from a symptomatic Great horned owl.
--
John P. Maher
******
[2]
Date: 25 Sep 2002
From: Hutchinson, Michael <mhutchinso@state.pa.us>
[In response to a query for additional information on the identification of West Nile virus in hippoboscidae, Michael Hutchinson was kind enough to send the following. - Mod.MPP]
Thank you for your question about the positive louse flies. We have sent 3 pools of Hippoboscidae for West Nile virus testing. The first pool of 5-6 specimens was taken from a Red Tail (RT) hawk that tested positive for WN - that pool tested negative. The second pool contained 5 specimens that were collected from a symptomatic Great Horned (GH) owl. That is the pool that tested positive through PCR as well as through virus isolation, indicated the presence of live virus. This is not surprising in that the specimens were visibly blooded. The results from a 3rd pool of non-blooded specimens are still pending. Future submissions of Hippoboscids from symptomatic birds will be held in the lab for 7-10 days to try to ensure complete digestion of the blood meal. Positive results from non-blooded insects will give us a better idea if the virus can survive within the louse flies. We will still be in need of vector competency studies to nail down the importance, or lack thereof, of this group. As for the question about the identity if the flies, they are in the genus Icosta and I'm waiting on literature to provide a species level identification. There are about 8 species in North America and they are bird biters.
Michael L. Hutchinson
Biologist - West Nile Virus Program
PA Department of Environmental Protection