University News for July 19, 2010

The University of Manitoba reports higher numbers of the mosquito species that carry West Nile Virus are expected to result in higher numbers of West Nile Virus in Manitoba this year.

Warm temperatures and rain are needed for mosquitoes to reproduce in large numbers and Manitoba has had both this year resulting in higher mosquito populations than last year.

Aedes vexans has accounted for over 90 percent of the adult mosquitoes collected so far this year but higher numbers of Culex tarsalis and Culex restuans, the species capable of carrying West Nile Virus and other arboviruses, are also reported.

Dr. Mahmood Iranpour, an adjunct professor with the University of Manitoba's Faculty of Agricultural and Food Sciences, says the risk of contracting West Nile peaks in late summer.

Clip-Dr. Mahmood Iranpour-University of Manitoba:
The research has been done in the last couple of years.

The risk of the West Nile Virus for humans is high at the end of the summer in August and September.

The researchers think that because they are migratory birds...they go from north to south at the end of the summer...then these species Culex tarsalis and restuans which are primarily bird feeders, feed on the birds when the birds are around.

When the birds migrate south they switch from birds to humans and that is the time that they transmit the West Nile Virus and some other arboviruses to humans.

Basically the end of the summer, August and September, to me is basically the time that there's a high risk of transmitting the disease to humans.

Dr. Iranpour notes since the arrival of West Nile Virus in Canada in 2003-2004, the number of cases has fluctuated from year to year.

He notes there were no cases reported last year in Manitoba but, because of the higher mosquito numbers, he expects we'll certainly see cases of West Nile virus this year.

For UniversityNews.Org, I'm Bruce Cochrane.

*University News is a presentation of the University of Manitoba's Faculty of Agricultural & Food Sciences