West Nile Virus

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Wnv was first confirmed in Canada in August 2001 in a wild bird in Ontario. In 2002, the virus was found in wild birds in Saskatchewan, Manitoba, Ontario, Quebec, and Nova Scotia. Exposure of horses to WNv was confirmed in 2002 in Saskatchewan, Manitoba, Ontario and Quebec. In 2002, human cases were reported in Alberta, Ontario, and
  Quebec. The Alberta cases are believed to have contracted the disease while travelling outside of Alberta. However, in 2003, cases of WNv were reported in Alberta.
Symptoms of West Nile virus
 
Most persons infected with WNv have either mild symptoms or no symptoms at all. Symptoms typically include fever, fatigue, headache and muscle or joint pain. Severe disease is uncommon, but signs and
 
Most persons infected with WNv have either mild symptoms or no symptoms at all. symptoms may include fever, a stiff neck, disorientation, tremors, muscle weakness and paralysis. Symptoms occur three to 15 days following the bite of an infected mosquito. No specific treatment exists for WNv infection and there is no approved vaccine to prevent the infection in humans. Any worker who suspects they have symptoms of WNv should seek medical attention.

How workers become infected with West Nile virus
  Humans can become infected with WNv after being bitten by an infected mosquito. In areas where WNv has been detected, less than one percent of mosquitoes carry the virus. Fewer than one percent of individuals bitten by a mosquito infected with WNv will develop serious symptoms. This makes the risk of contracting the disease very low.
  The primary reservoir of the virus is birds, especially members of the Corvid family which includes crows, blue jays, ravens and magpies.
  Mammals in general are very resistant to WNv infection. Humans, horses, donkeys and mules are the most susceptible mammals. Many other animals may be infected, including cattle, chickens, mountain goats, wolves and squirrels, but clinical disease is rare. House pets such as cats and dogs are not at risk for serious illness due to WNv, and do not transmit infection to humans.

Workers at risk
  Workers most likely to be infected with WNv are those who work outdoors and have a chance of being bitten by a mosquito infected with WNv. Bird and mosquito surveillance programs have been
identifying areas of the province at greatest risk.
 
Although the risk is very low, evidence indicates that skinpenetrating injuries involving objects contaminated with infected blood or body fluids are potential sources of infection. Public safety personnel, health care workers, veterinary and laboratory workers whose work includes the possibility of skin-penetrating punctures or lacerations are also at risk while handling WNv-infected tissue or fluids. WNv may also be transmitted through organ transplantation and blood transfusion.
Workers most likely to be infected with WNv are those who work outdoors and have a chance of being bitten by a mosquito infected with Wnv.