2013 Surveillance for West Nile virus in Manitoba


Positive Surveillance Indicators*
Surveillance Indicator 2013 2012 2011

Corvids 1

__

__

__

Mosquito Collections (Adult)

19

116

0

Horse Cases

1

7

0

Human Cases (Total) 2

3

39

0

Surveillance Indicator 2010 2009 2008

Corvids 1

__

__

__

Mosquito Collections (Adult)

20

2

41

Horse Cases

0

0

0

Human Cases (Total) 2

0

2

12

Surveillance Indicator 2007 2006 2005

Corvids 1

__

__

12

Mosquito Collections (Adult)

948

171

193

Horse Cases

8

1

4

Human Cases (Total) 2

587

51

58

Surveillance Indicator 2004 2003 2002

Corvids 1

16

134

86

Mosquito Collections (Adult)

57

290

15

Horse Cases

0

47

236

Human Cases (Total) 2

3

143

0

* As of December 12, 2013

1The West Nile virus dead corvid pick up program is not in effect in 2013. 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.

One bird submitted to the Canadian Cooperative Wildlife Health Centre (University of Saskatchewan) in 2013 has tested positive for WNV.

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Culex tarsalis Mosquito Trap Catch by Regional Health Authority*
Regional Health Authority May 19 - 25 May 26 - June 1 June 2 - 8

Interlake- Eastern 1

0

0

0

Southern Health-Santé Sud 2

0

0

0

Prairie Mountain Health 3

0

0

0

Winnipeg

0

0

0

Manitoba 0 0 0
Regional Health Authority June 9 - 15 June 16 - 22 June 23 - 29

Interlake- Eastern 1

<1

<1

<1

Southern Health-Santé Sud 2

<1

<1

3

Prairie Mountain Health 3

<1

<1

1

Winnipeg

<1

<1

<1

Manitoba <1 <1 1
Regional Health Authority June 30 - July 6 July 7 - 13 July 14 - 20
Interlake- Eastern 1 <1 4 18
Southern Health-Santé Sud 2 8 18 71
Prairie Mountain Health 3 1 9 9
Winnipeg 1 15 31
Manitoba 3 13 36
Regional Health Authority July 21 - 27 July 28 - August 3 August 4 - 10
Interlake- Eastern 1 21 5 3
Southern Health-Santé Sud 2 67 20 23
Prairie Mountain Health 3 16 2 5
Winnipeg 26 6 4
Manitoba 36 9 10
Regional Health Authority August 11 - 17 August 18 - 24 August 25 - 31
Interlake- Eastern 1 1 3 4
Southern Health-Santé Sud 2 4 23 9
Prairie Mountain Health 3 7 34 15
Winnipeg 1 15 9
Manitoba 3 21 10
Regional Health Authority September 1 -
September 7
September 8 -
September 14
 
Interlake- Eastern 1 <1 0  
Southern Health-Santé Sud 2 1 1  
Prairie Mountain Health 3 2 1  
Winnipeg 1 <1  
Manitoba 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 December 12, 2013

Permanent mosquito traps are set up in 29 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 8 . All trapping has now concluded for the 2013 season.

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Positive Mosquito Collections (Adult) by RHA*
Positive Mosquito Collections (Adult) by RHA

Interlake- Eastern 1

0

Southern Health-Santé Sud 2

12

Prairie Mountain Health 3

3

Winnipeg

4

Total 19

Mosquito samples from the following communities have tested positive for WNV in 2013: Altona, Boissevain, Carberry, Killarney, Morden, Morris, Portage la Prairie, West St. Paul, Winkler, 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 December 12, 2013

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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

0

1

0

1

Northern 2

0

0

0

0

0

Southern Health-Santé Sud 3

0

1

0

0

1

Prairie Mountain Health 4

0

0

0

0

0

Winnipeg

0

1

0

0

1

Total
0
2
1
0
3
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 December 12, 2013 - May include cases pending classification

Note:  2013 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
0
0
0
20 - 29
0
0
0
0
0
30 - 39
0
1
0
0
1
40 - 49
0
1
0
0
1
50 - 59
0
0
0
0
0
60 - 69
0
0
0
0
0
Over 70
0
0
1
0
1
Total
0
2
1
0
3

* As of December 12, 2013 - May include cases pending classification

Note:  2013 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

0

1

0

1

Female

0

2

0

0

2

Total
0
2
1
0
3

* As of December 12, 2013 - May include cases pending classification

Note:  2013 human case classifications include both final and preliminary classifications and may be subject to change as further information becomes available.

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Weekly WNV Surveillance Report

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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