West Nile a bigger threat | Ontario recently reported a case of eastern equine encephalitis, which can be deadly
Saskatchewan’s provincial veterinarian says horse owners should be more concerned about vaccinating for West Nile virus than western equine encephalitis.
Betty Althouse said no cases of WEE have been confirmed in the province since the early to mid-1980s and, although she doesn’t know exactly why, it is likely due to good vaccine protocol.
Last week, Ontario reported a horse in Simcoe County was recovering after being diagnosed with eastern equine encephalitis, or EEE.
The Ontario agriculture ministry said Aug. 28 the 11-year-old gelding suffered acute onset of depression and fever, as well as neurological signs.
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The horse had an incomplete vaccination history and had not travelled outside Canada.
Horses on the same property are all fully vaccinated and are showing no signs of the disease.
Dr. Janet Alsop, a ministry veterinarian, said EEE is typically quite severe and the death rate is high. In this case, the horse may have been vaccinated in the past, which helped it survive.
She said EEE was first found in Ontario in 1938 and sporadic cases have occurred since.
It can occur in humans, but no cases have ever been reported in Ontario.
“It’s always a concern to public health,” she said, referring to the ministry’s decision to issue a news release and notify veterinarians.
Althouse said EEE is typically found east of the Great Lakes and the Mississippi River, while WEE was more common through the agricultural region of the North American west and midwest.
EEE is considered more severe than WEE. Symptoms include circling, head-pressing and convulsions. Those same symptoms could indicate other diseases such as rabies, West Nile virus and lead poisoning.
It can cause severe disease in humans, including permanent brain damage or death, but no human cases of EEE have ever been reported in Ontario.
It can also kill birds and dogs.
Public health officials across Canada are surveying mosquitoes for West Nile virus and Ontario is screening for EEE.
Birds are the natural hosts for both diseases, and mosquitoes are the vectors after they bite infected birds.
No mosquitoes have tested positive in Ontario this year for EEE.
There were no confirmed cases of EEE in horses last year. In 2011, there were four confirmed and one probable equine cases and an outbreak in pheasants.
West Nile continues to cause concern for humans and horses. Althouse said there is more risk of contracting that disease than encephalitis.
