2012 Surveillance for West Nile virus in Manitoba

Positive Surveillance Indicators*
Surveillance Indicator 2012 2011 2010
Corvids 1 __ __ __
Mosquito Collections (Adult)
116
0
20
Horse Cases
7
0
0
Human Cases (Total) 2 39 0 0
Surveillance Indicator 2009 2008 2007
Corvids 1 __ __ __
Mosquito Collections (Adult)
2
41
 948
Horse Cases
0
0
 8
Human Cases (Total) 2 2 12 587
Surveillance Indicator 2006 2005 2004
Corvids 1 __ 12 16
Mosquito Collections (Adult) 171 193 57
Horse Cases 1 4 0
Human Cases (Total) 2 51 58 3
Surveillance Indicator 2003 2002  
Corvids 1 134 86  
Mosquito Collections (Adult) 290 15  
Horse Cases 47 236  
Human Cases (Total) 2 143 0  

* As of October 6, 2012

1The West Nile virus dead corvid pick up program is not in effect in 2012. Dead corvids are no longer needed as an early indicator of West Nile virus in Manitoba or to determine geographic distribution. Larval sampling, mosquito sampling and testing in addition to other factors (temperature, etc.) will be used to guide the assessment of risk of West Nile virus exposure.

2Additional information on these cases including classification, age, gender, regional health authority of residence and likeliest area of exposure is available here.

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Culex tarsalis Mosquito Trap Catch by Regional Health Authority*
Regional Health Authority Sept. 16 -
Sept. 22		 Sept. 9 -
Sept. 15		 Sept. 2 -
Sept. 8
Interlake- Eastern 1 0 0 <1
Southern Health-Santé Sud 2 <1 <1 10
Prairie Mountain Health 3 <1 0 2
Winnipeg <1 <1 2
Manitoba <1 <1 4
Regional Health Authority August 26 -
September 1		 August 19 -
August 25		 August 12 -
August 18
Interlake- Eastern 1 1 1 6
Southern Health-Santé Sud 2 17 10 43
Prairie Mountain Health 3 2 4 19
Winnipeg 8 1 9
Manitoba 8 4 21
Regional Health Authority August 5 -
August 11		 July 29 -
August 4		 July 22 -
July 28
Interlake- Eastern 1 10 16 24
Southern Health-Santé Sud 2 107 331 210
Prairie Mountain Health 3 88 297 184
Winnipeg 33 31 34
Manitoba 68 200 129
Regional Health Authority July 15 -
July 21		 July 8 -
July 14		 July 1 -
July 7
Interlake- Eastern 1 11 14 13
Southern Health-Santé Sud 2 77 20 25
Prairie Mountain Health 3 81 15 10
Winnipeg 20 26 17
Manitoba 53 19 17
Regional Health Authority June 24 -
June 30		 June 17 -
June 23		 June 10 -
June 16
Interlake- Eastern 1 3 3 <1
Southern Health-Santé Sud 2 6 1 3
Prairie Mountain Health 3 4 <1 <1
Winnipeg 4 3 <1
Manitoba 4 2 1
Regional Health Authority June 3 -
June 9		 May 27 -
June 2		 May 20 -
May 26
Interlake- Eastern 1 1 <1 <1
Southern Health-Santé Sud 2 1 <1 <1
Prairie Mountain Health 3 <1 <1 <1
Winnipeg 4 3 <1
Manitoba 2 <1 <1

1 Includes the former Interlake and North Eastman RHAs
2 Includes the former Central and South Eastman RHAs
3 Includes the former Assiniboine, Brandon and Parkland RHAs.

* As of October 6, 2012

Permanent mosquito traps are set up in 33 community areas in southern Manitoba to monitor Culex tarsalis mosquitoes, the mosquitoes that are most likely to transmit West Nile virus to humans in Manitoba. The above table will represent the average number of Culex tarsalis mosquitoes per trap catch for the week by Regional Health Authority (RHA) and  provides a relative measure of the activity levels of Culex tarsalis from one RHA to another and over time. This measure is an indicator as to whether Culex tarsalis mosquito populations are rising or falling or staying steady. It should be noted that these RHA averages provide an approximate indication of the number of Culex tarsalis in the RHA, counts in specific locations within the RHA will vary depending on local conditions, temperature, precipitation, etc.

Note:  normally, two Centers for Disease Control (CDC) mosquito traps baited with carbon dioxide are run for two nights each week in each Manitoba community except Winnipeg and Brandon (where proportionately more traps are used because of larger community size). 

The average number of Culex tarsalis per trap catch (a trap catch – may also be called a “collection”- represents the mosquitoes collected by one trap during one night from approximately one hour before sunset until approximately one hour after sunrise) is calculated by dividing the total number of Culex tarsalis collected for the whole week in a given RHA by the number of collections.

Based on the time of year and declining Culex tarsalis numbers reduced trapping commenced on the weekend of September 8th.

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Positive Mosquito Collections (Adult) by RHA*
Positive Mosquito Collections (Adult) by RHA
Interlake- Eastern 1
13
Southern Health-Santé Sud 2
48
Prairie Mountain Health 3
35
Winnipeg
20
Total
116

Mosquito samples from the following communities have tested positive for WNV in 2012: Altona, Beausejour, Brandon, Boissevain, Carberry, Carman, Deloraine, East St. Paul, Killarney, Morden, Niverville, Oakbank, Portage la Prairie, Sandy Bay FN, Selkirk, Sioux Valley FN, Ste Anne, St. Andrews, Steinbach, Stonewall, Stony Mountain, Virden, West St Paul, Winkler and the City of Winnipeg.

1 Includes the former Interlake and North Eastman RHAs
2 Includes the former Central and South Eastman RHAs
3 Includes the former Assiniboine, Brandon and Parkland RHAs.

* As of October 6, 2012

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WNV Human Cases by Regional Health Authority*

Represents the Regional Health Authority of residence of the patient.

Regional
Health
Authority		 Asymptomatic West Nile Virus Non-Neurological Syndrome West Nile Virus
Neurological Syndrome		 Unclassified Positive
Test
Results		 TOTAL
Interlake- Eastern 1
0
3
2
0
5
Northern 2
0
0
0
0
0
Southern Health-Santé Sud 3
0
14
2
0
16
Prairie Mountain Health 4
0
4
1
0
5
Winnipeg
0
8
5
0
13
Total
0
29
10
0
39
Out of Province
0
0
0
0
0

1 Includes the former Interlake and North Eastman RHAs
2 Includes the former Burntwood and NorMan RHAs
3 Includes the former Central and South Eastman RHAs
4 Includes the former Assiniboine, Brandon and Parkland RHAs.

* As of October 28, 2012 - May include cases pending classification

Note:  2012 human case classifications include both final and preliminary classifications and may be subject to change as further information becomes available.

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Severity of WNV Disease By Age*
Age in Years Asymptomatic West Nile Virus Non-Neurological Syndrome West Nile Virus
Neurological Syndrome		 Unclassified Positive
Test
Results		 Total
  0 -   9
0
0
0
0
0
10 - 19
0
0
1
0
1
20 - 29
0
4
0
0
4
30 - 39
0
5
0
0
5
40 - 49
0
6
0
0
6
50 - 59
0
9
2
0
11
60 - 69
0
4
4
0
8
Over 70
0
1
3
0
4
Total
0
29
10
0
39

* As of October 28, 2012 - May include cases pending classification

Note:  2012 human case classifications include both final and preliminary classifications and may be subject to change as further information becomes available.

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WNV Disease by Gender*
Gender Asymptomatic West Nile Virus Non-Neurological Syndrome West Nile Virus
Neurological Syndrome		 Unclassified Positive
Test
Results		 Total
Male
0
20
7
0
27
Female
0
9
3
0
12
Total
0
29
10
0
39

* As of October 28, 2012 - May include cases pending classification

Note:  2012 human case classifications include both final and preliminary classifications and may be subject to change as further information becomes available.

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Additional information and maps are available at the Public Health Agency of Canada website.

For WNV health concerns, contact your doctor or call:

Health Links - Info Santé
204-788-8200 (Winnipeg) or toll-free 1-888-315-9257