West Nile Virus Surveillance Summary #9

Feb. 10, 2010, 10:35 a.m.

 

Thursday, September 10, 2009

WNV Activity in BC

(Data as of September 9, 2009) 

The second human case of WNV in BC has been confirmed.  This case was a family member of the first confirmed human case and reported travel in the southern Okanagan.   One new mosquito pool has tested positive for WNV, for a total of nine positive pools to date in 2009.  All positive pools were in the Okanagan Health Service Delivery Area.   

The BCCDC webpage on West Nile can be viewed directly at: http://www.bccdc.ca/dis-cond/a-z/_w/WestNileVirus/default.htm 

From June 1st, 2009

Humans*

Corvids submitted

Corvids sighted

Mosquito pools

# Tested

225

124

372

2238

# Positive

2

0

 

9

*includes routine screening of CSF, organ and stem cell donations in addition to physician test requests 

Maps and graphs of BC surveillance data can be found at: http://www.bccdc.ca/dis-cond/a-z/_w/WestNileVirus/Surveillance/WNv2009SurveillanceData.htm 

7-day Environment Canada weather forecast for select BC communities

Warm and dry conditions are forecasted for BC over the next week. Abbotsford, Vancouver and Victoria are expecting sun and temperatures ranging 27-10oC.  Osoyoos, Kamloops, Creston and Cranbrook are expecting sun and temperatures ranging 31-5oC.   

Accumulated base 16 oC growing degree days comparison for select BC communities

  August 31st

2009

2008

2007

2006

2005

2004

2003

30YR

  Cranbrook

368

366

442

423

307

360

476

276

  Creston

519

414

607

554

446

517

620

351

  Osoyoos

750

649

687

687

680

809

786

540

  Kamloops

696

580

579

657

575

704

662

475

  Abbotsford

385

280

295

342

340

430

360

222

  Vancouver

289

204

221

239

245

329

275

170

  Victoria

255

189

207

237

239

296

263

153

  Prince George

252

185

189

237

184

264

196

139

 

All communities experienced dramatically increased accumulated degree days this year compared to last year and the 30 year average.  Degree day calculations beyond August 31st are not calculated as newly hatched mosquitoes have entered diapause by this time (a state where they do not seek a blood meal); therefore, the effect of temperature on mosquito development and viral replication after this time does not contribute to WNV risk.

WNV Activity in Canada

(Data as of September 9, 2009)

 

Human Cases (confirmed)

Positive Corvids (confirmed)

Positive Mosquito pools

Positive Equine Cases

BC

2

0

9

0

Alberta

1

n/a

n/a

0

Saskatchewan

0

1

11

0

Manitoba

0

0

2

0

Ontario

0

3

0

1

Total

3

4

22

1

AB, SK and MN and ON are not testing corvids as part of their WNv programs, all birds have been tested by the Canadian Cooperative Wildlife Health Centre

AB is not testing mosquito pools

WNV Activity in the US

·         Washington:

·         There has been 1 human case, 326 positive pools, 15 positive birds and 32 positive horses.

·         King County reported activity for the first time in the 2009 season this week with one dead crow reported positive.

·         Oregon:

·         There have been six human cases, 15 positive birds, 3 positive horses and 258 positive mosquito pools reported.  No new activity has been reported since last surveillance report.

·         Activity has been reported in 5 Counties located in the north and eastern part of Oregon.

·         California: 

·         There have been 29 human cases reported in 40 counties, 405 dead birds, 845 mosquito pools, 171 sentinel chicken flocks, 6 horses and 6 squirrels have been reported as positive to date in 2009.

·         Montana:

·         One new human case has been reported for a total of four cases to date.

 

Other US states reporting WNV activity:

(Data as of Sept 8; Sources:  USGS survey)

196 human cases of WNV have been reported in 28 States.  49% of human cases have been reported as encephalitis/meningitis.  Six fatalities have been reported.  The number of human cases reported continues to be lower compared to previous seasons.   

 

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