Rabies: Outbreak in Southwestern Ontario in raccoons and skunks
Photo from Lincoln County Humane Society depicts a raccoon from Grimsby that was picked up in February, 2016, sick with distemper.
Once considered one of the world’s two worst hotspots for rabies, Ontario is again battling an outbreak of the deadly disease on the doorstep of Southwestern Ontario.
At the end of July there were already 162 confirmed cases of rabies in wildlife, and more have been found in August.
Two years ago, for the entire year, there were just 18 confirmed cases in the province.
“We are baiting the area as we speak,” Chris Davies, manager of the wildlife research and monitoring section of Ontario’s Natural Resources and Forestry Ministry, said this week.
The rabies cases, a strain of raccoon rabies, have been concentrated in the Hamilton area with a few cases found as far west as Brantford.
It’s the second time Ontario has been hit with the raccoon strain of rabies that originated in Florida decades ago and moved north about 50 kilometres a year up the U.S. eastern seaboard.
“We knew it was coming,” Davies said.
Although raccoon rabies had been found just across the border in the U.S., there was a surprise when Canadian Food Inspection Agency tests showed it had originated from an area in northern Vermont.
“We believe it probably arrived on an open apple truck. Vermont exports a lot of apples for food processing down in the Hamilton area,” Davies said.
Named for its main carrier, two-thirds of the raccoon rabies cases in the latest outbreak have been found in raccoons and one-third in skunks.
The first indication of the outbreak came Dec. 4, 2015, when Davies’ team got a call from the Hamilton health unit that a raccoon had been in a fight with two dogs in the back of an animal control vehicle. The raccoon was tested for rabies.
“We were on the ground and running within 24 hours. We had it confirmed over the weekend and on Monday morning we had staff in the field with Hamilton folks distributing baits,” Davies said.
More than 220,000 of the baited vaccines were either dropped by plane, helicopter or distributed by hand in December. Normally that would have been the vaccination effort for a year, but there was a problem with the timing.
The offspring of the raccoons and skunks emerging in the spring had no immunity from the vaccine until they were 16 weeks old, so the vaccination drops have to be repeated again, covering a zone within 50 kilometres of any confirmed case.
“This is the exceptional year because of when it occurred. Now we are getting them all,” Davies said.
The 50-km bait zone was adopted because research has shown that’s the maximum distance a raccoon will move in a year, Davies said.
The good news in battling the outbreak, Davies said, is the disease hasn’t moved towards Toronto. Although it could take as long as four to five years to wipe it out, he expects they will be able to keep it from reaching the London area.
“I will be a lot more comfortable when the winter comes and we’ve got our bait throughout the whole area done,” he said.
Davies said Ontario was fortunate to have 700,000 vaccine baits in storage, ready to use. If officials had to wait the six months it takes to manufacture the vaccine “it would not have been a good story,” he said.
When the first outbreak of raccoon rabies was discovered near Brockville in 1999, the vaccine developed for fox rabies didn’t work. Instead, ministry staff had to capture and vaccinate animals, reduce the population of raccoons, skunks and foxes, and use a vaccine imported from the U.S. It took until September, 2005 to eliminate raccoon rabies from Ontario.
The fight against raccoon rabies is expected to cost $4 million to $5 million this year. That’s a lot of money, Davies said, but the annual cost of raccoon rabies spreading across Ontario has been calculated at $6 million to $12 million.
When the ministry is finished its current vaccination drop in the zone around Hamilton, an area that extends as far west as Woodstock, it will turn attention to an area north of Stratford where two cases of fox rabies were confirmed this year.
The pair are the first cases of fox rabies detected in Ontario in five years.
It was fox rabies, moving south from the Arctic in the 1950s, that turned Ontario into a hotspot for the disease.
By the 1970s, Ontario was being hit with two to three thousands cases a year.
The fox strain of the disease was virtually eliminated with the made-in-Ontario vaccination program using the air-dropped baits.
Davies said it’s believed the two cases north of Stratford are from a very low-level infection that went undetected. Vaccine will be dropped in October in a zone that covers Perth and parts of Huron, Middlesex, Oxford, Wellington counties and the Region of Waterloo.
While Davies is optimistic the raccoon and fox rabies can again be wiped out in Ontario, there is little that can be done for rabies in the other major wildlife carrier — bats. Because bats rely on insects for food, there’s no known way to entice them to consume the rabies vaccine.
“They are insectivores, so I don’t know how you do could do it,” Davies said.
ONTARIO’S CHANGING RABIES PICTURE
Cases detected in animals
2016: Through July: 162 cases
2015: 24 cases
2014: 18 cases
2013: 28 cases
2012: 28 cases
2011: 26 cases
Source: Canadian Food Inspection Agency
- Between 1924 and 2009, 24 people in six provinces died of rabies:
- The breakdown: Quebec, 12; Ontario, 6; Saskatchewan and Alberta, two each; British Columbia and Nova Scotia, one each.
- The three most recent human cases in Canada were bat-related.
Source: Public Health Agency of Canada