42 cases of West Nile reported in Alberta this season, most since 2007

By Gillian Slade on October 6, 2018.

gslade@medicinehatnews.com  @MHNGillianSlade

The number of confirmed cases of West Nile virus in Alberta this year has soared to the most seen since 2007.

Across the province, 42 cases have been diagnosed and of those 33 are in Alberta Health Services’ south zone.

It may seem late in the season to be talking about a virus transmitted by mosquitos but the data was collected over the past few weeks, said medical officer of health Lizette Elumir.

“People may also have been bitten but then not developed symptoms until later,” said Elumir.

Of the 42 cases across the province, 32 were non-neurological and five neurological. There was no data available from AHS on the seriousness of the five neurological cases or whether there have been any deaths.

West Nile virus can cause West Nile Non-neurological Syndrome or, on rare occasions the more serious West Nile Neurological Syndrome.

Those with West Nile Non-Neurological Syndrome may experience fever, chills, nausea, vomiting, fatigue, skin rash, swollen glands and headache. People who develop West Nile Neurological Syndrome may experience tremors, drowsiness, confusion, swallowing problems, high fever, unconsciousness, paralysis and even death.

This year’s statistics are also the highest in the south zone since 2007. There were four cases in 2017, three in 2016, none in either 2014 or 2015. In 2013 there were 16 cases, six in 2012, none in 2011 and 2010, one in 2009, one in 2008 and then 245 in 2007.

The reason the south zone’s numbers are significantly higher than the rest of the province is thanks to its warmer weather and ideal breading conditions for this particular mosquito.

If the temperature is 18 C it takes around 30 days for Culex tarsalis (the larvae carrying the virus) to be able to transmit the virus. With temperatures of 30 C it takes less than a week, according to government documents.