West Nile Disease Update

 

September 23, 2011

 

 

     In early September we diagnosed the first case of WEST NILE VIRUS  infection in a horse in the Central Okanagan.  This horse had been vaccinated yearly for the disease up to and including 2010, but WAS NOT vaccinated in 2011.  This horse had not traveled out of our area.  The horse was presented with unusual  central nervous system abnormalities.  Blood tests were conducted to try to identify the cause, and West Nile Virus infection was one of the tests requested.  Preliminary blood test results revealed marked inflammation consistent with an infections process and an antibody titer for West Nile Disease in the suspicious range.  Resampling for West Nile Virus titer two weeks later revealed a much higher antibody titer leading the laboratory to confirm that this was in fact an active case of West Nile Virus infection.

      Over the past decade, the West Nile virus has spread over almost all of North America with British Columbia being one of the last holdouts.  We have continued to recommend booster vaccination against the disease every spring, but unfortunately, some owners have elected to discontinue the vaccination boosters with the belief that their horses were safe in British Columbia.  In no way are we suggesting that we have an outbreak at the present time.  What we do know, however, is that we obviously have at least some mosquitoes in our area that are carrying the virus.

 

THINGS TO REMEMBER:

 

- The virus does not spread from horse to horse

-The disease is actually a bird disease that is only accidentally spread to horses and humans

- Horses can get the virus in their system and show no signs, or they can get ill from it.

-Of horses that show clinical signs of disease, historically about 20% die and others may be left with permanent brain impairment.

 

VACCINE IS AVAILABLE AND IS VERY EFFECTIVE AT PREVENTING THE DISEASE

 

     It is too late this fall to vaccinate horses to protect them because they require two shots about a month apart and by that time, our mosquito season will be over.

     We will be reminding all our clients in the spring of 2011 to be sure to update all their horses with West Nile Virus vaccinations.