2010 Surveillance for West Nile virus in Manitoba

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

* As of September 22, 2010

1The West Nile virus dead corvid pick up program is not in effect in 2010. 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*
Average Adult Culex tarsalis Mosquitoes per Weekly Trap Catch
Regional Health Authority

May 16 -
May 22

May 23 -
May 29

 May 30 -
June 5
Assiniboine 0 0 <1
Brandon 0 0 0
Central 0 0 11
Interlake 0 0 0
North Eastman 0 0 0
Parkland 0 0 0
South Eastman 0 0 1
Winnipeg 0 0 <1
Manitoba 0 0 2
Regional Health Authority

June 6 -
June 12

June 13 -
June 19

June 20 -
June 26
Assiniboine 2 <1 1
Brandon 0 0 0
Central 3 4 21
Interlake <1 <1 7
North Eastman <1 <1 2
Parkland 0 0 <1
South Eastman <1 <1 14
Winnipeg 2 1 13
Manitoba 1 1 9
Regional Health Authority

June 27 -
July 3

July 4 -
July 10

July 11 -
July 17
Assiniboine 28 121 69
Brandon 5 68 18
Central 93 285 77
Interlake 20 202 52
North Eastman 7 158 56
Parkland 1 11 8
South Eastman 48 313 97
Winnipeg 35 230 106
Manitoba 37 190 70
Regional Health Authority

July 18 -
July 24

July 25 -
July 31

August 1 -
August 7
Assiniboine 258 409 224
Brandon 69 230 211
Central 172 385 331
Interlake 73 144 147
North Eastman 95 127 240
Parkland 7 96 57
South Eastman 42 229 257
Winnipeg 134 537 235
Manitoba 139 335 229
Regional Health Authority

August 8 -
August 14

August 15 -
August 21

August 22 -
August 28
Assiniboine 347 110 69
Brandon 408 36 18
Central 238 81 65
Interlake 79 35 16
North Eastman 134 26 15
Parkland 16 9 3
South Eastman 94 26 9
Winnipeg 183 80 130
Manitoba 210 66 59
Regional Health Authority

August 29 -
Sept. 4

Sept. 5 -
Sept. 11

 Sept. 12 -
Sept. 18
Assiniboine 1 <1 0
Brandon <1 0 0
Central 1 <1 <1
Interlake 2 <1 0
North Eastman 1 <1 0
Parkland <1 0 n/a
South Eastman 1 <1 <1
Winnipeg 3 <1 <1
Manitoba 2 <1 <1

* As of September 22, 2010

NOTE:  Routine mosquito trapping was discontinued the week ending September 11, 2010.  Reduced trapping in representative communities occurred the week ending September 18, 2010.

Permanent mosquito traps are set up in 37 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.

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Positive Mosquito Collections (Adult) by RHA*
Positive Mosquito Collections (Adult) by RHA
Assiniboine
5
Brandon
2
Central
3
Interlake
1
North Eastman
1
Parkland
0
South Eastman
1
Winnipeg
7
Total
20

Mosquito samples from the following community have tested positive for WNV in 2010: West St. Paul, Beausejour, Russell, Boissevain, Stonewall, Winnipeg, Brandon, Sioux Valley, Morden, Altona, Carberry, Morris and Steinbach.

* As of September 22, 2010

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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
Assiniboine
0
0
0
0
0
Brandon
0
0
0
0
0
Central
0
0
0
0
0
Interlake
0
0
0
0
0
NorMan
0
0
0
0
0
North Eastman
0
0
0
0
0
Parkland
0
0
0
0
0
South Eastman
0
0
0
0
0
Winnipeg
0
0
0
0
0
Total
0
0
0
0
0
Out of Province
0
0
0
0
0

* As of September 22, 2010

Note: 2010 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
0
0
0
0
40 - 49
0
0
0
0
0
50 - 59
0
0
0
0
0
60 - 69
0
0
0
0
0
Over 70
0
0
0
0
0
Total
0
0
0
0
0

* As of September 22, 2010

Note: 2010 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
0
0
0
Female
0
0
0
0
0
Total
0
0
0
0
0

* As of September 22, 2010

Note: 2010 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