Three cases of West Nile di­ag­nosed in Al­berta

Medicine Hat News - - COMMUNITY - WEST - GIL­LIAN SLADE gslade@medicine­hat­news.com Twit­ter: MHNGil­lianSlade

Three cases of West Nile virus have been con­firmed in the prov­ince.

One was in Cal­gary and two in the Al­berta Health Ser­vices’ south zone which, in­cludes Medicine Hat.

There are a num­ber of fac­tors that in­flu­ence the preva­lence of West Nile-car­ry­ing mos­qui­toes, in­clud­ing an ac­cu­mu­la­tion of what are called “de­gree days.” A to­tal of 109 De­gree Days above 14.3 C are re­quired for 50 per cent of mos­qui­toes to be able to trans­mit the virus, ac­cord­ing to on­line de­tails. The risk of trans­mis­sion in­creases with the in­crease of De­gree Days.

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.

In the past, West Nile sea­son ac­tiv­ity has started once the 150-200 De­gree Day thresh­old is met in the south­east of the prov­ince.

Ac­cord­ing to a pro­vin­cial map show­ing De­gree Days, ef­fec­tive Aug. 20, a swath of land cov­er­ing Saska­toon and Cal­gary has 350-400 de­gree days while this re­gion sits at the 250-300 mark.

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.

In 2003, there were 275 cases of West Nile in Al­berta and in 2007 there were 320. The num­bers dropped dras­ti­cally af­ter that with only one in 2008, two in 2009, nine cases in 2012 in­clud­ing a lo­cal man who died that Oc­to­ber from West Nile Neu­ro­log­i­cal Syn­drome. There were 21 cases in 2013 and then noth­ing un­til last year when there were five cases, three of which were in the south of the prov­ince, ac­cord­ing to data pro­vided on Al­berta Health’s web­site.

It is not pos­si­ble to tell which mos­qui­toes near you are car­ry­ing West Nile virus, so it’s best to avoid be­ing bit­ten at all, says Al­berta Health Ser­vices. Use an in­sect re­pel­lent that con­tains DEET and limit your time out­doors at dawn and dusk when mos­qui­toes are most ac­tive. Cover up with long-sleeved shirts and long pants in light colours.

https://open.al­berta.ca/dataset/west-nile-virus-and­de­gree-days-maps-in-al­berta-in-2017

http://www.al­ber­ta­health­ser­vices.ca/info/page1 4953.aspx

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