Published Date: 2003-07-19 23:50:00
Subject: PRO/AH/EDR> West Nile virus, birds: antibody - UK
Archive Number: 20030719.1772

WEST NILE VIRUS, BIRDS: ANTIBODY - UK
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Date: Sat 19 Jul 2003
From: "Pablo Nart" <p.nart@virgin.net>
Source: BBC News online, Sat 19 Jul, 2003 [2003]
<http://news.bbc.co.uk/1/hi/sci/tech/3079425.stm>

West Nile virus neutralising antibody in resident and migrant birds in the UK
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Evidence of the potentially deadly West Nile virus has been found in a high
proportion of British birds, scientists have revealed. The virus is
transmitted by mosquitoes and the researchers have warned that the risk of
the virus spreading to humans is increasing with the impact of climate change.
There have been no cases of West Nile virus infection of humans in the
United Kingdom but the virus caused the death of more than 270 people in
the US last year.
Scientists at the Centre for Ecology and Hydrology [formerly the NERC
Institute of Virology] in Oxford tested birds mainly in Cambridgeshire, but
also in Dorset and South Wales. They found evidence of the virus in more
than half the birds tested -- an "unexpectedly high" proportion, BBC
science correspondent Christine McGourty said. It was found in more than 20
species in all, including crows, magpies, swallows, chickens, turkeys, and
ducks.
While the birds were healthy and showed no symptoms, scientists did detect
antibodies to the virus. This indicated the birds had come into contact
with the virus and that their natural defences had successfully fought it
off. It is thought that the virus is being brought into the country by
migrating birds.
The researchers said there was no immediate threat to humans, but warned
that climate change might increase the risk. The research, published on Sat
19 Jul 2003, comes after increased surveillance measures for the virus were
introduced in the UK. The chief medical officer for England, Sir Liam
Donaldson, announced the measures in early July, saying the risk to human
health was low, but doctors and health officials had been urged to be on
the look-out for symptoms.
--
ProMED-mail
<promed@promedmail.org>
[The publication referred to in this report was published on Fri 18 Jul
2003 in the online advance edition (JGV Direct) of the Journal of General
Virology for October 2003 (Buckley A, Dawson A, Moss SR, Hinsley SA,
Bellamy PE, Gould EA. Serological evidence of West Nile virus, Usutu virus
and Sindbis virus infection of birds in the UK.
<http://www.sgm.ac.uk/JGVDirect/19341/19341a.htm>).
The abstract of the paper reads as follows: "The introduction and rapid
dispersal of the African flavivirus West Nile virus (WNV) throughout North
America, and the high fatality rate due to encephalitis in birds, horses,
other wildlife species and humans, has attracted major attention worldwide.
Usutu virus, another flavivirus, came to prominence in 2001, when it was
identified as the agent responsible for a drop in the bird population in
Austria; previously this encephalitic virus was found only in birds and
mosquitoes in Africa. Sindbis virus, a pathogenic alphavirus that causes
arthritis, is widespread throughout Africa, Europe, Asia and Australia,
infecting a range of arthropods and vertebrates and is genetically related
to encephalitic viruses in North America. Currently there is no evidence
that any of these viruses cause disease in the UK. Here the presence of
virus-specific neutralizing antibodies is reported in the sera of resident
and migrant birds in the UK, implying that each of these viruses is being
introduced to UK birds, possibly by mosquitoes. This is supported by
nucleotide sequencing that identified three slightly different sequences of
WNV RNA in tissues of magpies and a blackbird. The detection of specific
neutralizing antibodies to WNV in birds provides a plausible explanation
for the lack of evidence of a decrease in the bird population in the UK
compared with North America. The potential health risk posed to humans and
animals by these viruses circulating in the UK is discussed."
The apparent absence of disease in arthropodborne virus infected British
wild birds in contrast to the behavior of introduced West Nile virus in
North America and Usutu virus in Austria is striking. To what extent this
phenomenon may be due to genetic differences in the virulence of virus
strains, to routes of transmission, or to vector specificity are intriguing
questions for future analysis. - Mod.CP]

See Also

2002
---
Usutu virus, emergence in Europe (02) 20020918.5339
Usutu virus, emergence in Europe 20020722.4838
....................cp/sh
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