A: West Nile virus was first detected in the U.S. in 1999, in horses on Long Island, New York. Over 15,000 U.S. horses have been infected.
West Nile virus was first detected in Canada in 2001. In 2002, there were 356 Canadian horses reported positive for West Nile virus. In 2003, the number increased to 445, a 25% increase in clinically affected horses in Quebec, Ontario, Manitoba, Saskatchewan and Alberta. West Nile will continue to spread in 2004.