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WEST NILE VIRUS, WILD BIRD - UK: CORRECTION
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A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases
<http://www.isid.org>
Date: 24 Jul 2009
The 23 Jul 2009 ProMED post reporting West Nile virus (WNV) in a dead
crow (ProMED archive 20090723.2607) was mistakenly identified as
having occurred in the United Kingdom, when, in fact, the crow was
found in Ontario, Canada. WNV is endemic in Ontario, so the crow
fatality due to this virus is not surprising. ProMED regrets the
error and any inconvenience it may have caused. ProMED thanks Dr.
Helen Roberts, Dr. Mirzet Sabirovic and Matthew Hartley for calling
the error to our attention. [Several other correspondents also noted
the error - Mod.LM]. They indicated that further information about
WNV in the UK, can be found in the 24 Feb 2009 Qualitative Risk
Assessment:
<http://www.defra.gov.uk/animalh/diseases/monitoring/pdf/qra-wnv-090210.pdf>.
The summary of this report is:
This qualitative risk assessment specifically addresses the
likelihood of the introduction of West Nile Virus (WNV) from abroad
to the UK via various pathways and its potential to become
established in the UK.
With regard to the introduction of WNV from abroad, we currently consider that:
a) There is a continuous very low risk of WNV being introduced by
migrating birds.
b) The likelihood of the introduction of WNV to the UK via legal
trade in horses and other equidae is very low;
c) The likelihood of the introduction of WNV to the UK via legal
trade of equine semen, ova and embryos, equine meat, specified
biologicals and research samples is negligible;
d) The likelihood of the introduction of WNV to the UK via legal
trade in live poultry and captive birds, hatching eggs and poultry
meat is negligible;
e) The likelihood of the introduction of WNV to the UK via legal
trade in live non-avian/non-equidae species, including ungulates, is
negligible;
f) Although possible, the likelihood of the introduction of the virus
via illegal or non-compliant movements of equidae/poultry is
difficult to quantify. It is also impossible to quantify the
likelihood of introduction of virus by as yet unrecognised routes;
g) There is a very low risk of WNV being accidentally introduced with
imported plants or by means of transport;
Should the disease be introduced to the UK, we currently consider that:
a) Local dissemination would depend upon the abundance of competent
vectors; their feeding patterns; bird density and their
migratory/local dispersal patterns; environmental considerations,
including adequate temperatures that would favour mosquito activity
and replication of the virus in mosquitoes;
b) The potential for establishing an enzootic cycle between
potentially WNV infected hosts (mainly wild birds) and potentially
competent local mosquito populations in the UK is very low, as this
is subject to fulfilment of optimal epidemiological, entomological
and ecological conditions occurring in combination.
c) There would be some impact on the UK horse industry as the
infection may result in disease and mortality in some horses, in
which case movements of horses from affected holdings would be
subject to official control in line with EU rules.
With regard to availability of vaccines for WNV, we note that:
a) A number of vaccines have been deployed in North America, which
are considered to be effective in protecting horses against WNV and
have helped reduce the number of cases in horses.
b) A WNF vaccine (Duvaxyn WNV) has recently been given marketing
authorisation for use in horses in the EU.
With regard to availability of diagnostic tests WNV, we consider that:
a) At present, testing is offered in the UK to private vets for the
differential diagnosis of neurological disease in horses (the Plaque
Reduction Neutralisation Test). For general surveillance in wild
birds, and diagnosis of WNV in horse CNS tissue, a PCR technique is
used which is the National Reference Method and will detect both WNV
lineages. Therefore the UK currently has sufficiently sensitive tests
to diagnose WNV in both suspect cases and surveillance programmes.
--
Communicated by:
ProMED-mail
<promed@promedmail.org>
[Additional WNV cases in the UK can be expected to be rare, and the
above assessment indicates that this virus has not become endemic
there. Results of sentinel bird monitoring for evidence of WNV
transmission in the UK will be of interest. WNV infections in birds,
humans and horses in southern Canada can be expected to occur
annually. - Mod.TY]
[See also:
West Nile virus, wild bird - UK 20090723.2607]
.........................lm/ty/ejp/lm
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