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Myxomatosis

| Disease Found in Oregon | Disease Claims 9 out of 10 Rabbits | Outbreak Could See Thousands Die |

Myxomatosis is a deadly disease which is spread by fleas and mosquitoes that affects only rabbits. It is caused by the myxoma virus which is a member of the poxvirus group. Myxomatosis, causes localized skin tumors among the genus Sylvilagus (cottontail rabbits), however, the European rabbit (Oryctolagus cuniculus) is more severely affected by the disease and death is almost certain.

The CFIA's (Canadian Food Inspection Agency) annual report of 2005 to the OIE  (World Organization for Animal Health) stated there have been no reported outbreaks of myxomatosis in Canada. Myxomatosis is currently classed as an "annually notifiable disease" where the CFIA is responsible for providing the OIE with an annual report indicating the presence or non-presence of the disease within Canada. The 2006 report has not yet been made available. Myxomatosis is endemic in the USA and is mainly restricted to the coastal areas of California and Oregon.

Early indications of Myxomatosis include conjunctivitis which may lead to blindness as well as visible  lumps (myxomata) and puffiness around the head and genitals. Rabbits soon develop a fever, lose their appetite and become listless. Secondary bacterial infections are next to occur such as pneumonia and purulent inflammation of lumps. The mortality rate in the USA is anywhere from 25-90% with death usually occuring on an average of 13 days after exposure.

RABBIT DISEASE FOUND AGAIN IN OREGON

07-21-04

By David Stauth, 541-737-0787
SOURCE: Dr. Christiane Loehr, 541-737-9673

CORVALLIS - For the second year, an outbreak has been confirmed in Oregon of a rabbit disease called myxomatosis, and veterinary experts at Oregon State University say that rabbit owners should understand the continued threat from this disease and consider precautions to protect their animals.

Last summer, the first serious outbreak of the disease in more than a decade was identified in Linn and Benton counties in Oregon, prompting the closure of rabbit shows at the county fairs in those two areas. Myxomatosis is a disease with an extremely high mortality rate that shows up somewhat unpredictably in the European rabbits most commonly reared in Oregon.

In the past two weeks, about 14 of the 21 rabbits owned by a resident of Rogue River in southern Oregon died, and a necropsy on one of the animals by pathologists in the OSU College of Veterinary Medicine has established the diagnosis of myxomatosis.

"Mid- to late-July is about when we would expect to see problems from a continuing epidemic of myxomatosis, but at this point we have no reason to believe the problems will be as bad as last year," said Dr. Christiane Loehr, an OSU veterinary pathologist. "It's at least possible that last year was the peak of this epidemic and the problem will slowly improve. It depends partly on how bad of a mosquito season we have, which plays a role in transmission of the disease."

There are no official recommendations at this time to avoid rabbit shows, Loehr said.

"Mostly, we just want to remind people who own rabbits that this disease is still with us, that they should learn about the problems it can pose and consider taking precautions to protect their animals," Loehr said.

Myxomatosis is highly contagious, is transmitted naturally by mosquitoes or other insects, and can be spread from rabbit to rabbit by human handlers. It has no cure. In Oregon there is no diagnostic test for live animals and no readily available vaccine. The last time a major outbreak occurred in the 1980s it caused a significant number of rabbit deaths in the Willamette Valley and southern Oregon. The disease can have a mortality rate higher than 90 percent in European rabbits. There are some basic precautions that rabbit owners can take to protect their animals, experts say.

The most important is mosquito netting, which may help protect against mosquito and other insect transmission. However, animal handlers should be careful about use of such netting in very hot weather, since it may impair air flow in rabbit hutches.

Beyond that, the best prevention is avoiding groups of other rabbits that may be infected, such as at rabbit shows or county fairs.

Myxomatosis is caused by a poxvirus that has a natural reservoir, perhaps among brush rabbits. It is far less deadly to wild rabbits, although they, too, can be affected. It's not clear what triggers the periodic outbreaks among domesticated rabbits, but possible factors may include immunity levels in wild populations, heat stress, other weather conditions, and wild rabbit and mosquito populations.

Symptoms of the disease can include high fever, loss of appetite, swelling of mucus membranes or sluggishness. Mortality is linked to a suppression of the animals' immune system, making them vulnerable to a host of other health problems. Skin nodules called "myxomas" may appear in some cases. But at times an animal has appeared fairly healthy, and then died the next day.

There is no treatment other than supportive care for secondary infections, veterinary doctors say, and no vaccine is readily available. All domesticated rabbits in the U.S. are highly susceptible to the virus, but humans are not. If a rabbit is exposed to an infected rabbit, it should be quarantined for 14 days and assumed to be infected during that period. To help monitor the spread of the disease, anyone who owns a rabbit that dies from an unknown cause is encouraged to contact their local veterinarian or arrange for a necropsy by the Veterinary Diagnostic Laboratory at OSU, at 541-737-3261. There will be a fee for the necropsy.

More detailed information on myxomatosis is available on the website of the OSU College of Veterinary Medicine, at http://www.vet.orst.edu.

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Last Update:Wednesday, 21-Jul-2004 13:43:33 PDT

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Deadly disease may claim 9 out of 10 rabbits in UK

 

The worst outbreak of myxomatosis in years is threatening Britain's rabbit population, and owners of domestic animals are being warned to get their pets vaccinated without delay.

Reports are coming in of outbreaks of the disease across the country, with epidemics confirmed in Dorset, East Sussex, Essex, Newcastle, Cambridge, Durham and Surrey. Experts are blaming mild conditions in the autumn.

More than 90 percent of rabbits -- wild and domestic -- that contract myxomatosis die. The disease is carried by insects such as mosquitoes, ticks, mites, lice and fleas. An outbreak in the early 1950s almost wiped out the UK's rabbit population.

Claire King, executive officer at the Rabbit Welfare Association, the UK's largest rabbit owners' organization, said: "It is now everywhere in the country. Rabbit owners should take their rabbits down to the vet and vaccinate them. They should do it as soon as possible. This is the worst outbreak for years."

The disease begins with lumps around the rabbit's head and genitals. Acute eye infection follows, causing discharge and, usually, blindness. The rabbit then loses its balance, stops eating, and develops a fever. Infections then occur, causing pneumonia and inflammation of the lumps. In typical cases, death takes about 13 days.

Rabbits were introduced into Britain by invading Roman legions 2000 years ago. The population, estimated at 37.5 million, is at its highest for half a century.

Myxomatosis was 1st observed in laboratory rabbits in Uruguay in 1896. It was tolerated by South American rabbits but proved lethal to their European cousins. The disease was deliberately introduced into
Australia to devastating effect in 1950. In the autumn of 1953, it arrived in Britain. Ministry of Agriculture officials tried to
contain it but failed.

2 years later, 99 percent of Britain's wild rabbits were dead. It was alleged that some farmers had spread the disease deliberately, as rabbits had been blamed for the destruction of vast swathes of crops.

The Pests Act of 1954 criminalized intentional transmission, but few prosecutions followed. The rabbit population has now grown to half of what it was before the disease spread.

Mairwen Guard, of Cottontails Rabbit Rescue in Westbury, Wiltshire, believes the high cost of vaccination -- between 10 to 20 GBP [17 to 34 USD] per rabbit -- is helping to spread the disease. She said: "Responsible pet owners already vaccinate their rabbits twice a year. Your average person will buy rabbits for their kids and then just leave them at the bottom of the garden when the family gets bored. It's no wonder that the disease spreads."

Dorothy and Ray Massey of the British Belgian Hare Club have over 70 animals in their barn in Wearmouth, Derbyshire. Mrs. Massey is prepared for the worst. "This outbreak could wipe the whole lot out," she said.

"All our stock, everything. We can't vaccinate, though. It's so costly to have the whole lot vaccinated, as well as making the does infertile."

The disease is not monitored by the Government. A spokesman for the Department for Environment, Food and Rural Affairs said yesterday [26 Nov 2005]: "This is not a notifiable disease. People whose pets catch it or who see it are not required by law to report it. It doesn't affect any other mammal."

[Byline: Tom Anderson]
 

A ProMED-mail post
<http://www.promedmail.org>

Archive Number 20051128.3445

Published Date 28-NOV-2005

Subject PRO/AH/EDR> Myxomatosis, rabbits - UK

 

Date: Sun 27 Nov 2005
From: A-Lan Banks <A-Lan.Banks@thomson.com>
Source: The Independent, UK, 27 Nov 2005 [edited]
<http://news.independent.co.uk/environment/article329577.ece>
 

Also Published 27 November 2005 in "The Independent"

By Tom Anderson

 

 


 Myxomatosis Outbreak Could See Thousands Die
 

 

A deadly outbreak of the rabbit killer disease, myxomatosis, is spreading across Huddersfield [Kirklees, south of Leeds, in northern England]. Hundreds of wild rabbits have already been killed by the virus, which is
spread by blood-sucking insects.

Several dog walkers have reported seeing dead rabbits daily on the Dalton Bank Nature Reserve. Many of the rabbits have inflamed ears and eyes, which are signs of the virus.

"There have been numerous dead rabbits or parts of rabbits around for the past week," said Deborah Nicholson, of Kirkheaton, who regularly walks her dog there. "The vet says the disease can't be passed on to dogs, but some
of the rabbits have either no eyes or very inflamed eyes, which are symptoms of the disease."

John Avison, environment coordinator for the chemical company Syngenta, Huddersfield, which manages the 50 acre nature reserve, said he was aware of the outbreak. "It only kills rabbits, not hares, but it can affect domestic rabbits," he said.

Mr Avison said the wild rabbit population had built up some resistance to the virus, but 90 per cent could be wiped out by this outbreak -- about 60 per cent by the virus and 30 per cent by predators -- as it leaves the rabbits blind and deaf and more at risk. He said he had seen 4 outbreaks of the virus in the 27 years he had worked at the reserve, the last being about 3 years ago. He urged dog walkers to keep their dogs on leads to avoid vulnerable rabbits being attacked while ill.

Vet Sibaele Collins, who works in Huddersfield, said the virus did flare up occasionally, but the surgery was seeing fewer and fewer cases in domestic rabbits, because many owners were vaccinating against the disease. The standard rabbit vaccination, which includes myxomatosis, costs about GBP 25 [USD 48].

Peter Bolton, animal welfare manager for the Royal Society for the Prevention of Cruelty to Animals in the north east, said the charity strongly recommended owners of pet rabbits to have them vaccinated against the virus. "It does exist in the wild rabbit population, which is why we encourage people to vaccinate in case pet rabbits come into contact with wild ones," he said. "It is an horrific death for rabbits, but unfortunately it happens, and it is just nature's way of controlling the rabbit population."

[byline: Hazel Ettienne]
 

A ProMED-mail post
<http://www.promedmail.org>
Archive Number 20041208.3256

Published Date 08-DEC-2004

Subject PRO/AH> Myxomatosis, rabbits - UK (England)

 

Date: Wed 8 Dec 2004
From: ProMED-mail <promed@promedmail.org>
Source: Huddersfield Examiner, 4 Dec 2004 [edited]

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