2020 Surveillance Data for West Nile virus in Manitoba
Positive West Nile virus (WNV) Surveillance Indicators*
Surveillance Indicators** 2020 2019 2018 Historical Maximum
WNV Positive Mosquito Collections (Adults) 3 7 168 948
Human Cases (Total)*** 0 2 32 588

* As of October 2, 2021

** The historical comparison data is based on the same period of time for each year represented in the table above.

*** Additional information on these cases including classification, severity and health region of residence is available here.

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Culex Tarsalis Mosquito Trap Catch by Health Region
Trapping Week Health Region Manitoba
Interlake-Eastern Prairie Mountain Southern-Santé Sud Winnipeg

May 17-  May 23
No trapping
No trapping
0
0
0

May 24 – May 30
No trapping
No trapping
0
0
0

May 31 – June 6
No trapping
No trapping
0
<1
<1
June 7 – June 13 No trapping <1 0 <1 <1
June 14 – June 20 No trapping 2 1 1 2
June 21 – June 27 2 <1 <1 1 1
June 28 – July 4 8 19 17 8 13
July 5 – July 11 11 19 16 4 13
July 12 – July 18 8 151 19 14 37
July 19 – July 25 15 121 66 34 56
July 26 – August 1 25 176 46 25 55
August 2 – August 8 8 134 26 16 37
August 9 – August 15 16 66 62 53 52
August 16 – August 22 5 70 27 11 25
August 23 – August 29 4 67 4 9 16
August 30 – Sept. 5 <1 1 <1 <1 <1
Sept. 6 – Sept. 12 <1 <1 <1 <1 <1

* As of October 2, 2020

Permanent mosquito traps are set up in 21 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 Cx. tarsalis mosquitoes per trap catch for the week by health region and provides a relative measure of the activity levels of Cx. tarsalis from one region to another and over time. This measure is an indicator as to whether Cx. tarsalis mosquito populations are rising or falling or staying steady. It should be noted that these health region averages provide an approximate indication of the number of Cx. tarsalis in the health region, counts in specific locations within the health region 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 health region by the number of collections.

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Positive Mosquito Collections (Adult) by Health Region
Positive Mosquito Collections (Adult) by Health Region

Interlake- Eastern

0

Prairie Mountain

2

Southern-Santé Sud

0

Winnipeg

1
Total
3

* As of October 2, 2020

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WNV Human Cases by Health Region*
Classification
Health Region**
 Total
Interlake-Eastern
Prairie Mountain
Southern-Santé Sud
Winnipeg
Probable

0

0

0

0

0
Confirmed

0

0

0

0

0
Total
0
0
0
0
0

* As of October 2, 2020

** Based on region of residence. Note that region of residence may not correspond to region of likely exposure.

Note:  Subject to change as further information becomes available.

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Severity of WNV Human Cases
 
Asymptomatic
West Nile Virus
Non-Neurological Syndrome
West Nile Virus Neurological Syndrome
Under
Investigation
Total
Human Cases
0
0
0
0
0

* As of October 2, 2020

Note:  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