Efficacy of Vaccination for West Nile Virus in Saskatchewan Horses

摘要

Preliminary analysis of studies conducted during the 2003 outbreak of West Nile Virus in Saskatchewan showed that vaccination was strongly associated with the prevention of clinical disease at both the individual horse and the farm level. In North America, West Nile Virus (WNV) was first diagnosed in horses in the late summer of 1999. Symptoms ranged from mild to severe with a case fatality rate of 25-40%. Not all infected horses developed clinical symptoms. One report suggests that only 10% of horses infected with WNV will exhibit neurological symptoms. Other than geographic location and age, factors associated with the development of disease have not been reported in previous studies. Factors associated with serocon-version include geographic location, age, housing, and use of horses. A variety of methods of mosquito control and housing of horses have been suggested as means of decreasing the exposure risk of susceptible horses to WNV. Controlled, challenge trials have shown protection against WNV in vaccinated horses.