Amid COVID-19 pandemic, deadly disease strikes rabbit populations
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It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Edmonton's syphilitic cemetery bunnies killed off by different rare rabbit disease
A fluffle of feral cemetery rabbits at a northwest Edmonton cemetery, plagued by a syphilis outbreak in 2020, has been wiped out by a different and rare illness.
Rabbit haemorrhagic disease (RHD) was discovered in three bunnies living in the colony at and around Holy Cross Cemetery in September, according to a memo from the Alberta government. By the end of September about 50 had died or disappeared
Very few, if any, are still alive.
“It was a very hot virus that rapidly ran through the colony and killed essentially all the feral domestic rabbits,” Margo Pybus, University of Alberta professor and wildlife disease expert, said in an email.
This disease is highly infectious with a rapid onset, and is almost always fatal in European rabbits, of which pet rabbits are descendants. It causes organ damage and internal bleeding. In some places it has spread to wildlife.
Before it was decimated, the libidinous fluffle of feral domestic rabbits lived at the cemetery and surrounding areas for about 30 years.
Klack’s group began capturing bunnies with syphilis symptoms — including fur loss, and crusting or sores on the eyes, mouth and genitals — in the summer of 2020 with the cemetery’s permission. But many rabbits were much sicker than expected, so rescuers were allowed to take any they could find.
Of about 200 rescued Klack said only 130 survived.
“Every rabbit we caught ended up being just overloaded with normally two to three different types of worms and parasites along with the syphilis,” they said in a recent interview.
Many were malnourished and had reproductive cancers, they said.
“A lot of volunteers got really burnt out because the rabbits they were rescuing were dying three days later. There was literally nothing we could do even with the best vet care,” they said. “I kept joking that my backyard is just one giant graveyard.”
The rabbits, and volunteers, also had to deal with hungry predators: “I had a volunteer chased out by coyotes. They were just feasting on those rabbits.”
With rescue efforts the colony began shrinking but numbers climbed again earlier this year, said Klack.
As they was preparing to resume rescues, a single case of RHD was confirmed in southern Alberta. Volunteers instead focused on getting rabbits already in care vaccinated.
While Klack had always hoped one day the colony would disappear — as domestic rabbits aren’t fit to live in the wild — they hoped it would be because the bunnies found new homes.
“I’m sad that I couldn’t rescue more, but knowing that there isn’t a giant colony out there that’s sick with syphilis and worms and all sorts of nasties, and that coyotes won’t be as big of a problem, that makes me happy,” they said. “It’s very much a multifaceted feeling.
“There’s not going to be more generations upon generations of rabbits just being born to suffer and die.”
Alberta’s first case of RHD was detected in Taber in March. The onset is quick and early symptoms can go undetected. Rabbits often die suddenly .
While the disease is new to Alberta, there were outbreaks in feral domestic rabbits in B.C. in 2018 and 2019.
Wild rabbits and hares have typically been immune to RHA, but a new strain killed some wildlife in the western United States and northern Mexico last year, according to an Alberta government handout. Alberta’s mountain cottontails, white-tailed jackrabbits, snowshoe hares and pikas may be at risk.
So far there isn’t evidence the disease spread to local wildlife.
But according to the BCSPCA, genetic sequencing of the case found in southern Alberta closely resembles the strain in the U.S. which has killed and infected wild animals.
“This has significant implications for wild rabbit welfare as well as ecosystem health, and also means that if the virus spreads to B.C., it could be virtually impossible to eliminate,” reads a release on the organization’s website this summer.
There is no treatment or cure for RHD. Vaccines aren’t approved in Canada but the B.C. government procured some using an emergency provision. Some Alberta veterinarians also ordered shipments from the B.C. government, but this program was recently discontinued.
Sorelle Saidman, president of Rabbitats Rescue Society in B.C., who helped co-ordinate efforts for some Alberta veterinarians to get vaccines said Alberta needs to make vaccines available. But, she said, many don’t care about rabbits.
“They’re not barking for attention, they’re not purring when they’re getting their pets … (but) they’re very affectionate, very sentient. They just need extra protection because they seem so unassuming.”
Request for information from the Alberta government about how the disease arrived, how many and which kinds of animals have been killed, and whether it is working to acquire RHD vaccines were not answered by deadline.
Rabbit virus has evolved to become more deadly, new research finds
AND AS THEY HAVE FOUND IN CALGARY
by Pennsylvania State University
A common misconception is that viruses become milder over time as they become endemic within a population. Yet new research, led by Penn State and the University of Sydney, reveals that a virus—called myxoma—that affects rabbits has become more deadly over time. The findings highlight the need for rigorous monitoring of human viruses, including SARS-CoV-2, monkeypox and polio, for increased virulence.
"During the COVID-19 pandemic, many people have incorrectly assumed that as the SARS-CoV-2 virus becomes endemic, it will also become milder," said Read.
"However, we know that the delta variant was more contagious and caused more severe illness than the original strain of the virus, and omicron is even more transmissible than delta. Our new research shows that a rabbit virus has evolved to become more deadly, and there is no reason why this couldn't happen with SARS-CoV-2 or other viruses that affect humans."
According to Read, myxoma was introduced to Australia in the early 1950s to quell an out-of-control non-native rabbit population. Known as "myxomytosis," the disease it caused resulted in puffy, fluid-filled skin lesions, swollen heads and eyelids, drooping ears and blocked airways, among other symptoms. The virus was so deadly that it killed an estimated 99.8 percent of the rabbits it infected within two weeks.
Over time, however, the virus became milder, killing only 60% of the rabbits it infected and taking longer to do so.
"Scientists at the time believed this outcome was inevitable," said Read. "What they called the 'law of declining virulence' suggested that viruses naturally become milder over time to ensure that they do not kill their hosts before they've had a chance to be transmitted to other individuals."
Yet, when Read and his team began to study the myxoma virus in rabbits in 2014, they found that the virus had regained the upper hand and was once again killing rabbits at a higher rate. In their most recent study, which published on Oct. 5 in the Journal of Virology, they examined several myxoma virus variants collected between 2012-2015 in the laboratory to determine their virulence. The team determined that the viruses fell into three lineages: a, b and c.
Interestingly, Read said, the rabbits in their study exhibited different symptoms than those induced by viruses collected in the first decades after the release.
"Instead of developing puffy, fluid-filled lesions, these rabbits developed flat lesions, suggesting a lack a reduced immune response," said Read.
"In addition, these rabbits had significantly more bacteria distributed throughout multiple tissues, which is also consistent with immunosuppression. We interpreted this 'amyxomatous' phenotype as an adaptation by the virus to overcome evolving resistance in the wild rabbit population."
Lineage c, however, produced a slightly different response in rabbits. Rabbits infected with lineage c had significantly more swelling at the base of the ears and around the eyelids, where mosquitoes typically bite. These areas also contained extremely high amounts of virus.
"Insect transmissibility is dependent on high amounts of virus being present in sites accessible to the vector," said Read. "We hypothesize that lineage c viruses are capable of enhanced dissemination to sites around the head where mosquitoes are more likely to feed and that they are able to suppress inflammatory responses at these sites, allowing persistent virus replication to high amounts."
Read said that the team's findings demonstrate that viruses do not always evolve to become milder.
"By definition an evolutionary arms race occurs when organisms develop adaptations and counter-adaptations against each other," said Read.
"With myxoma, the virus has developed new tricks, which are resulting in greater rabbit mortality. However, over time the rabbits will likely evolve resistance to these tricks. An analogous arms race may be occurring with SARS-CoV-2 and other human viruses as humans become more immune. This is why it's so important for vaccine manufacturers to keep up with the latest variants and for the public to stay up to date on their vaccines. Better still would be to develop a universal vaccine that would work against all variants and be effective for a longer period of time."
The research was published in Journal of Virology.
European wild rabbits are a 'keystone species' that hold together entire ecosystems—according to researchers at the University of East Anglia.
Their grazing and digging activity keeps the ground in a condition that is perfect for sustaining other species that would otherwise move on—or die out.
But their numbers are declining regionally, nationally and globally. And they are even being classed as endangered in their native region, the Iberian Peninsula.
The findings come as efforts to save England's most threatened species from extinction are turning the tide for wildlife in Norfolk and Suffolk thanks to the Shifting Sands project.
Shifting Sands is one of 19 projects across England that make up the national Back from the Brink initiative. Together, these projects aim to save 20 species from extinction and benefit over 200 more.
Lead partner of the rabbit workstream and rabbit expert Prof Diana Bell, from UEA' School of Biology, said: "The Breckland-based Shifting Sands project was set up to save some of the region's rarest wildlife.
"After several years of hard work by this multi-partner project, the fortunes of species classed as declining, rare, near-threatened or endangered are now improving in the Brecks.
"The project has seen species recover in record numbers—including endangered beetle and plants, one of which is found nowhere else in the world.
"Rabbits are incredibly important because their grazing and digging activity keeps the ground in a condition that is perfect for sustaining other species.
"Sadly, rabbit populations have declined dramatically in the UK and across Europe, and the European wild rabbit is now listed as endangered in its ancestral Iberian Peninsula range. Their decline is largely due to a spill-over of new viruses from commercially bred rabbits.
"The Shifting Sands project has shown us how important rabbits are to entire ecosystems, and it is vital that these habitats are conserved and protected.
"We encouraged a rabbit revolution in the Brecks and we have produced a toolkit in partnership with Natural England to help landowners of similar rabbit-dependent habitats to do the same."
"Simple cost-effective ways of encouraging rabbits include creating piles of felled branches, known as brush piles, and banks of soil."
Monitoring over the past three years has shown the interventions are working, with evidence of significantly higher amounts of rabbit activity.
Prof Bell said: "Our work resulted in evidence of rabbit activity in significantly higher numbers. 91 percent of brush piles showed paw scrapes and 41 percent contained burrows. Even when burrows did not form, the brush piles helped expand the range of rabbit activity."
The UEA research team worked in collaboration with Natural England, Forestry England, Plantlife, Breckland Flora Group, Norfolk Wildlife Trust, Suffolk Wildlife Trust, Butterfly Conservation, Buglife, the Elveden Estate and the RSPB to deliver this ambitious partnership project.
It has seen five kilometers of 'wildlife highways' created, more than 100 specimens of rare plants re-introduced, habitat created and restored across 12 sites, species encouraged, and landscape-management practices improved.
As a result, seven species of plant, bird and insect are increasing in number and many more are benefiting in turn.
Among those species recovering are rare plants such as the prostrate perennial knawel that is unique to the Brecks, basil thyme and field wormwood. The endangered wormwood moonshiner beetle, lunar yellow underwing moth and five-banded digger tailed wasp are also increasing. All these species are identified in the UK's Biodiversity Action Plan as being priorities for conservation.
The open habitat maintained by rabbits supports two rare plants: the prostrate perennial knawel—found nowhere else in the world—and field wormwood.
Pip Mountjoy, Shifting Sands project manager at Natural England, said: "The Brecks were described by Charles Dickens as "barren." They are anything but. Their 370 square miles of sandy heathland, open grassland and forest support almost 13,000 species, making it one of the UK's most important areas for wildlife.
"That wildlife is under threat. Felling trees and encouraging a species that is often considered a pest may seem a strange solution. But in this instance, carefully managed 'disturbance' is exactly what this landscape and its biodiversity needs."
"The project's interventions have provided a lifeline for this unique landscape, and shown how biodiversity can be promoted by 'disturbing' places—not just by leaving them alone. "
"These rare habitats are becoming overgrown and species are declining as a result of changing land management practices and human impacts. It's our responsibility to restore and maintain these spaces for nature. Some of these species exist only here and, if lost, will be lost forever.Feds say New England cottontail doesn't need protection
More information: More information about the Brecks, Shifting Sands, Back from the Brink and a toolkit to help rabbit conservation is available via https://naturebftb.co.uk/wp-content/uploads/2021/09/Shifting-Sands-Techniques-to-encourage-European-rabbit-recovery.pdf
Provided by University of East Anglia