The following article on Parapox virus in red squirrels is posted on ProMed-mail's
web site.
Virus threatens UK's red squirrels
A virus capable of devastating rare red squirrel populations has reached one
of the species' UK strongholds for the first time. It is killing squirrels
in Merseyside in north-western England, near the city of Liverpool.
The virus, parapox, which kills the animals within weeks or even days,
seldom responds to treatment [The author might be referring to symptomatic
treatment of this viral disease. - Mod. AS]. It is carried by grey
squirrels, though they are seldom harmed by it: the reds have no immunity.
The origins of parapox are unknown, but some grey squirrels are known to
carry antibodies. Red squirrels with the virus will have wet, discharging
lesions or scabs around the eyes, mouth, feet and genitals.
Infected animals resemble rabbits with myxomatosis, and are sometimes found
shivering and lethargic.
The Merseyside red squirrel population lives in Sefton, an area stretching
along the Lancashire coast from Southport down to Bootle.
A dead animal found there was taken for analysis to Liverpool University and
found to have been killed by the virus. Another dead squirrel is suspected
of having parapox. There are thought to be no more than 600-1,000 red
squirrels in the area.
In 1995 a nearby colony living around the town of Ormskirk was also affected
by parapox, and hardly any red squirrels are left there.
Steve White is the conservation officer for the Wildlife Trust for
Lancashire, Manchester and North Merseyside. He told BBC News Online: "Red
squirrels are declining catastrophically in the UK.
"The Sefton squirrels have done fairly well, because they thrive in the
pinewoods there, which the greys don't like so much.
"The reds have also been protected by the arable farmland behind the
pinewoods. But we think the greys are crossing that now and taking the virus
to them.
"So we're asking people to let us know about any sick or dead red squirrels
they may find, and also any greys, so we can trap them.
"We don't want people to touch sick or dead animals, because we don't know
whether humans can also carry the virus."
The trust is urging people who feed red squirrels in their gardens to
disinfect feeding equipment regularly.
Red squirrels were once widespread throughout the British Isles, but now
there are only about 160 000, most in Scotland. The number in England is
about 30 000, most of those in the north. There are around 10 000 on the
Welsh island of Anglesey, and some on the Isle of Wight and Brownsea Island
in the south of England.
Their decline is blamed on disease, the loss and fragmentation of woodlands,
and competition by the greys, which now number more than 2.5 million. They
can exploit deciduous woodlands better than the reds, and their breeding
prospects and adult survival rates are better there.
In conifer woods, though, the reds' survival chances are much higher.
[Byline: Alex Kirby]
[The decline of the red squirrel in the UK during the recent years may
have been the result of death caused by infection with a parapoxvirus
related to orf virus.
Orf (Contagious ecthyma) is a universally-spread disease, prevalent in all
sheep-raising countries, which causes proliferative lesions on the skin of
sheep, goats and humans. It poses a major health and welfare problem in
sheep, particularly in neonatal lambs and nursing ewes and leads to
significant economic losses for the farmer.
The orf virus is an epitheliotropic double-stranded DNA poxvirus of the
genus _Parapoxvirus_ (PPV) which also includes the closely related bovine
papular stomatitis virus, pseudocowpox virus and a PPV that infects deer.
Tentative members of the genus include a sealpox virus and viruses that
infect red squirrels and camels.
Research into the PPV disease in UK squirrels has been undertaken by
researchers of the Moredun foundation.
The Initial studies of the Orf
Virus were summarized
by Colin McInnes http://www.mri.sari.ac.uk/Virology/orf.htm
"An assay which measures antibody to the virus revealed that 61 percent of
apparently healthy grey squirrels have been exposed to the virus. In
contrast, only 3 percent of red squirrels were found to have antibody to
the virus, with 75 percent of these animals showing clinical signs of
squirrelpoxvirus-associated disease. These findings are consistent with the
suggestion that the virus causes little or no disease in the grey
squirrels, but is highly pathogenic for the reds. In addition, we found an
apparent correlation between the geographical distribution of grey
squirrels with antibody to the virus and the locations where
squirrelpoxvirus disease is known to, or thought to, have occurred, further
supporting the hypothesis that the grey squirrel may act as a reservoir
host for the virus. Future studies at the Moredun will concentrate on the
characterisation of the virus itself". The said article includes a map
pertaining to the distribution of the disease in the UK.
Moredun Research Institute identified several immunodominant orf virus
antigens by monoclonal antibodies (Mabs). Reportedly, these Mabs can be
used to differentiate different parapoxviruses from sheep, cattle, a seal
and a red squirrel.
Additional information on the Parapox
virus or the research being conducted in red squirrels at Moredun
Research Institute in the UK can be found on http://www.red-squirrels.org.uk/pdf/6DiseaseInSquirrels02.pdf
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