Facing the fact that the disease has become "established" in U.S. herds, Canadian inspectors will no longer respond to new cases of anaplasmosis starting next spring.
The Canadian Food Inspection Agency (CFIA) announced Monday it will remove anaplasmosis from Canada's list of federally reportable diseases effective April 1, 2014, placing it instead on the "immediately notifiable" list.
"The decision reflects the fact that anaplasmosis is established in the United States," the agency said in a statement. "There is a strong probability that anaplasmosis will enter Canada from the U.S. and the continuing to attempt to eradicate the disease within Canada may not be feasible."
Once that happens, only laboratories will be required to report suspected or confirmed cases of anaplasmosis to the CFIA, thus allowing Canada to still meet the annual reporting requirements of the World Organization for Animal Health (OIE) on the disease.
Furthermore, as of April next year, CFIA "will no longer respond" to anaplasmosis cases, nor run surveillance to verify Canada's status for the disease.
Anaplasmosis, caused by a micro-organism parasitic to red blood cells, affects ruminants including cattle, sheep, goats and deer, but only causes clinical signs in cattle and giraffes. It remains of "economic importance" to the cattle sector in infected countries, including the U.S. Even after an infected animal recovers, it remains a source of the disease for life.
The disease can be spread by ticks, biting flies or contaminated instruments such as hypodermic syringes and dehorning equipment. The types of ticks that can amplify and transmit anaplasmosis exist in Canada, CFIA said.
There is no human health risk associated with anaplasmosis, CFIA reiterated Monday. Another disease, human granulocytic ehrlichiosis (HGE) has been referred to as "human anaplasmosis" since 2003, but is caused by a different micro-organism.
By changing its approach to anaplasmosis, CFIA said it "will be able to focus more resources on emerging disease and foreign animal diseases." The planned changes aren't expected to affect international trade of Canadian livestock and related products, the agency added.
CFIA today regulates imports of livestock and related products from countries where anaplasmosis is known to occur, through port-of-entry inspections by the Canada Border Services Agency or CFIA. Right now, given its status as a reportable disease, suspected cases of anaplasmosis must be reported to CFIA for immediate investigation.
Since 1997, a class of "restricted feeder" cattle has been allowed for import without anaplasmosis tests but under certain post-entry conditions, by licensed feedlots to be fattened for slaughter only.
Until March 31, 2014, CFIA will still respond to new cases, but will follow only a scaled-back "interim approach." It will still test infected herds and run traceouts, but will no longer test susceptible animals in the areas surrounding an infected herd, nor test susceptible animals who may have come into contact with the infected herd.
CFIA will also still inform producers during the transition period if animals may have been exposed to the disease. Producers can continue to protect their animals "and their industry" through farm-level biosecurity and by contacting their veterinarians if they suspect their herd may be infected, the agency said.
Producers should also talk to their veterinarians about testing if their animals are or have been in close proximity to an infected animal or herd, CFIA said. The agency added it will work with provincial labs to develop testing capacity for anaplasma, and can provide, on request, a list of CFIA-approved labs that can already perform such testing.
Traditional tests for anaplasmosis were not as sensitive as the current DNA-based tests, and this may have contributed to the spread of anaplasmosis within the U.S., CFIA said.
Illness is rare in infected animals under six months of age, is "usually mild" from six months to one year of age, and is acute but "rarely fatal" in one- to two-year-old animals. Mortalities range from about 29 to 49 per cent in animals older than two years that have experienced clinical anaplasmosis, the agency said.
Clinical signs of the disease include fever, anaemia, weakness and "respiratory distress." Affected dairy cattle will also have a "rapid decline" in milk production, CFIA said.
No treatment for anaplasmosis has been licensed for use in Canada, CFIA said. Antibiotics are used preventatively in "high risk" areas in the U.S.
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