Two horses in the Thompson-Nicola area have tested positive for an infection of the West Nile virus.
One horse is in Cache Creek while the other is in Ashcroft.
The discovery has prompted veterinarians to warn horse owners to ensure their equine are vaccinated.
However, the Ministry of Agriculture says it isn’t ready to recognize the reported cases just yet.
The ministry stated it is following up these cases with the horses’ veterinarians to collect all the information needed to verify the reports.
One of a variety of tests needs to be conducted to assess changes in antibody levels, or a brain tissue sample following the animal’s death is needed to confirm the virus.
Both of the horses in question are alive.
Doctor John Twidale, chair of the equine committee for the Canadian Veterinary Medical Association-Society of B.C. Veterinarians (CVMA-SBCV), stated the two cases are the first in the area in B.C.
On its website, the BC Centre for Disease Control lists five cases of positive indicators of West Nile virus in horses in B.C. since 2009.
Twidale said to his knowledge, those horses had travelled out of B.C. at some point.
“These are the first two that have not been out of B.C. that I’m aware of,” Twidale said.
However, Ministry of Agriculture spokesperson Robert Boelens said the horses that had positive West Nile virus indicators in 2011 and 2013 did not have significant travel histories and acquired the virus in B.C.
Blood tests conducted by Cornell University on the two horses that recently tested positive for West Nile virus show a high level of antibody against the virus, which indicates an active infection, a CVMA-SBCV press release stated.
Twidale said the disease is only carried to horses or humans via infected mosquitoes, which contract the disease from biting infected birds. He also said it is not transmitted horse-to-horse or person-to-person and cannot be transmitted to humans by other animals.
“It’s not every mosquito bite that’s going to cause it; it’s not an epidemic. It’s going to be sporadic cases, but we just want horse owners to know that it is in the area and the only real prevention is vaccination ahead of exposure,” Twidale said.
The clinical signs of West Nile virus in horses include muscle tremors of the face, chest, body and hind legs, as well as fever, depression and the inability to stand in severe cases, the press release stated.
Twidale said it is too late to vaccinate a horse after symptoms of West Nile become apparent.
Horses should be given the vaccination annually, and those receiving it for the first time should be given two doses of the vaccine about three weeks apart, and then a single dose on an annual basis.
Twidale said horse owners should reach out to their local veterinarian to obtain the vaccine.
He said he’s been expecting to see cases of West Nile virus in horses appear in B.C. for the past five years as cases have been seen in the prairie provinces and in the U.S.
“Not every mosquito is carrying the virus; in fact, very few will, but there’s always that risk with horses,” Twidale said.
He said bringing horses into a barn at night is one way to help protect them against mosquitoes.
Carol Swan, a spokesperson with the BC Centre for Disease Control, said there have been no reported cases of West Nile virus in humans this year in B.C., although there have been human cases in the past.
The first human cases of West Nile in B.C. were reported in 2009, according to the Centre for Disease Control’s website.
There were some cases in 2007 and 2008, but they were considered to be travel-related.
Its website also stated West Nile virus is considered to be the most widely spread vector-borne disease in North America.
Between 2002 and 2012, there were 5,094 cases of West Nile in Canada in which people showed symptoms.
Most people who are infected will not show symptoms, but the disease can be serious for one in every 150 people who are infected, resulting in hospitalization.
This includes swelling of the brain and polio-like paralysis, but the fatality rate is 0.1 per cent.
People can avoid West Nile by avoiding mosquito bites. People can clean up mosquito-friendly areas such as pools of standing water; wear long-sleeved shirts and jackets; and wear mosquito repellent to avoid being bitten.
