West Nile virus infections detected in Winnipeg

Two Winnipeg blood donors have tested positive for the West Nile virus, marking the first human cases of the virus in Manitoba in two years.

Health officials say the virus was detected in two individuals who were tested by Canadian Blood Services as they were donating blood last week.

One person showed mild symptoms, namely headache and fatigue, while the other was said to have no symptoms, said Dr. Margaret Fast, the province's acting chief provincial public health officer.

Both individuals are in their 40s and live in Winnipeg, but Fast said it's not known if they were exposed to West Nile virus in the city or elsewhere in southern Manitoba.

Health officials are also trying to determine when the two may have contracted the virus.

The last time West Nile virus was detected in Manitoba was in 2009, when two human cases were reported. There were no cases in 2010 and 2011, Fast said.

In 2007,more than 500 human cases of West Nile viruswere diagnosed in Manitoba, andseveral deaths were connected to the illness. Thirty-eight cases werereported in the province in 2008.

Mosquito numbers rising

While some Manitobans have noticed fewer mosquitoes than usual so far this summer, Fast said Culex tarsalis mosquitoes, which carry the virus, have been detected in central and southern parts of the province.

"We do know that in southern Manitoba, the number of mosquitoes and the number of infected mosquitoes is increasing," she said.

"At the moment, we have 14 communities across southern Manitoba where we have identifiedpools of mosquitoes that are infected with the virus."

The ongoing hot and humid weather in the province will likely result in mosquito numbers continuing to rise, she added.

Fast said most individuals who are exposed to West Nile virus show no symptoms, while approximately 20 per cent may show some flu-like symptoms such as headaches, muscle aches and pain.

A very small number of people who are infectedcould develop neurological symptomsthat can cause paralysis, coma or in rare cases death.