Anaplasmosis has been found in five herds in eastern Manitoba.
Since January, the Canadian Food Inspection Agency has been investigating five cow-calf operations in the rural municipalities of Lac Du Bonnet and Alexander in an effort to determine the extent of the outbreak.
“All five infected farms have pastures that are in close proximity to each other. Testing is completed on two of the farms, and reactors (infected animals) are being ordered destroyed through slaughter,” Lynn Bates, a CFIA veterinary disease control specialist in Manitoba, said in an e-mail.
Read Also
Alberta may eliminate marked fuel
Alberta may soon stop selling dyed gasoline and diesel.
“Movement controls on the infected farms (quarantine) will be lifted once all the reactors are removed from the farm.”
Although she could not provide exact numbers because testing continues, Bates said in an interview that 32 out of 64 animals were infected in one of the Manitoba herds.
In a larger herd, 18 percent of the cattle tested positive for the disease, which is deadly for cows older than two and is commonly spread from animal to animal by ticks and re-use of dehorning and castrating tools and needles.
This outbreak is the second occurrence of the disease in Canada in the last year. One animal in a herd from southern Saskatchewan tested positive last fall, said CFIA spokesperson Tim O’Connor.
Two occurrences in such a brief period of time are unusual because anaplasmosis has only been detected in Canadian cattle five times since 1969, not including the two most recent incidents.
Canada was considered anaplasmosis free until the detection in Saskatchewan last October, O’Connor wrote in an e-mail.
According to a CFIA consultation paper on the disease, anaplasmosis destroys red blood cells and produces symptoms such as anemia and jaundice.
Infected cattle older than two will die 29 to 49 percent of the time. The disease is serious but rarely fatal in animals one to two years of age, while symptoms are mild in cattle younger than one.
Cow-calf operators are most affected by the disease, said CFIA senior staff veterinarian Dorothy Geale.
“(They) bear the brunt because they have the older animals.”
She said infected cows lose weight, produce less milk and abort calves.
More than 10 CFIA staff are involved in the investigation and are looking for antibodies that indicate the presence of the disease. They are also conducting blood tests to detect the DNA of A. marginale, the disease organism that attacks red blood cells.
The CFIA discovered the disease in both provinces after conducting a 15,000-sample bovine serological survey across Canada in 2007-08. The survey results led the CFIA back to the herds in eastern Manitoba because cattle from that region tested positive for anaplasmosis antibodies.
Bates said the Manitoba outbreak likely stems from an animal brought into the region.
“I think the source of anaplasmosis always in Canada would probably be a carrier animal,” Bates said.
“That’s probably the most likely source of it, from the U.S.A.”
While it is rare to find the disease in Canadian cattle, the CFIA consultation paper said it is common in the United States.
“Anaplasmosis has been identified as the second to fifth major production limiting disease in the U.S. with annual costs of $300 million, with a loss of 50,000 to 100,000 head in mortalities,” the paper said.
The disease is more common in the southern U.S., said Geale, who wrote the CFIA consultation paper.
“It first arrived there in about 1924, in Louisiana, and it’s been working its way north.”
The paper said it’s difficult to determine the prevalence of the disease in U.S. cattle because anaplasmosis reporting is voluntary under the National Animal Health Reporting System, and many states do not have sufficient data.
“They regard it as a producer responsibility … and there are various producers working to have a clean herd rather than working to have a clean state,” Geale said.
In contrast, anaplasmosis became a reportable disease in Canada in 1969 and herds that have the disease are put under quarantine.
Bates said the Manitoba investigation is not limited to the five herds because the CFIA is also tracking animals that came into or left the farms.
“That’s certainly part of our investigation, looking at any sources of farms where animals have been bought from, trace-in farms. Or looking where animals have left the farm, as trace-out. And we’ve been doing some testing on those animals that have left to go into breeding herds.”
Bates said the investigation will take as long as is required.
“We’ll carry on till we come to the end of it.”
