A Canadian study concluded that horses infected with West Nile virus (WNV) were not a reliable indicator for future human infections. The study was published in the June issue of Preventive Veterinary Medicine.

Researchers at the University of Saskatchewan reviewed 133 horse and 947 human WNV cases in Saskatchewan during the area’s 2003 WNV outbreak. They found that in most areas, clusters of human cases were not preceded by horse clusters. The study data did identify one area where “a significant cluster of horse cases preceded human cases by one week.”

Researchers, however, said that one week was not a sufficient amount of time to provide human-health officials with an early warning