Tag: Culex tarsalis

West nile virus

While the PPMN no longer predicts the development of Culex tarsalis, the dominant vector for West Nile Virus (WNV), areas of the Canadian prairies in 2024 have received high levels of precipitation. This is noteworthy because the larvae of C. tarsalis can develop in, “agricultural tailwater, alkaline lake beds, fresh and saline wetlands, secondary treated sewage effluent and oil field run-off” (Centre for Vector Biology URL retrieved 2024Jul04).

Culex tarsalis have a base developmental threshold of 14.3 °C. Across the Canadian prairies, WNV transmission is of greatest concern as the second generation of C. tarsalis females begin to fly (by 250-300 degree days). In fact, an additional 109 degree days (using Base 14.3 °C) is required within a given mosquito population for virus development to complete to the point that transmission might occur.

Historically, by mid-July, C. tarsalis adults begin to fly in southern parts of the Canadian prairies. By August, protect yourself from mosquitoes when outdoors – this is the window when mosquitoes are most numerous plus have the greatest chance of carrying WNV. Field scouts and outdoor enthusiasts should wear DEET to protect against C. tarsalis and WNV.

For reference, the following table of data was quickly generated using AAFC Drought Watch Historical Daily Air Temperatures since April 1, 2024:

Location	Degree Days (base 14.3 °C) as of August 21, 2024	Observed date heat units >200 Degree Days	Potential date when >390 Degree Days attained
Winnipeg	384.0	July 20	August 24
Brandon	302.8	July 27	Unable to project
Regina	352.9	July 26	September 2
Saskatoon	320.4	July 29	Unable to project
Lethbridge	331.2	July 25	Unable to project
Edmonton	205.9	August 20	Unable to project
Grande Prairie	239.2	August 11	Unable to project

Note: Potential dates calculated using daily mean of 18°C until August 30, 2024, then daily mean of 15°C for September 1-30, 2024.

The Public Health Agency of Canada posts information related to West Nile Virus in Canada. Link here to view the latest case numbers and seasonal updates. Bird surveillance continues to be an important way to detect and monitor West Nile Virus. The Canadian Wildlife Health Cooperative (CWHC) works with governmental agencies (i.e., provincial laboratories and the National Microbiology Laboratory) and other organizations to report the occurrence of WNV. Access information on surveillance posted by the provinces of Manitoba, Saskatchewan, or Alberta.

West nile virus

For reference, the following table of data was quickly generated using AAFC Drought Watch Historical Daily Air Temperatures since April 1, 2024:

Location	Degree Days (base 14.3 °C) as of August 13, 2024	Observed date heat units >200 Degree Days	Potential date when >200 Degree Days attained	Potential date when >390 Degree Days attained
Winnipeg	330.6	July 20	—	August 28
Saskatoon	266.2	July 29	—	Unable to project
Lethbridge	294.7	July 25	—	Unable to project
Edmonton	188.6	—	August 18	Unable to project
Grande Prairie	220.9	August 11	—	Unable to project

Note: Potential dates calculated using daily mean of 18°C until August 30, 2024, then daily mean of 15°C for September 1-30, 2024.

West nile virus

While the PPMN no longer predicts the development of Culex tarsalis, the vector for West Nile Virus (WNV), areas of the Canadian prairies in 2024 have received high levels of precipitation. This is noteworthy because the larvae of C. tarsalis can develop in, “agricultural tailwater, alkaline lake beds, fresh and saline wetlands, secondary treated sewage effluent and oil field run-off” (Centre for Vector Biology URL retrieved 2024Jul04).

Historically, by mid-July, C. tarsalis adults begin to fly in southern parts of the Canadian prairies. Field scouts and outdoor enthusiasts should wear DEET to protect against C. tarsalis and WNV.

West nile virus risk

The following is offered to help predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies. This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in Figure 1 but the unusual heat across the prairies greatly accelerated mosquito development!

As of August 21, 2022 and where present, C. tarsalis development has progressed. Remember, areas highlighted yellow have accumulated sufficient heat units for the second generation of C. tarsalis to fly. Many areas of the prairies well exceed the 250-300 DD of base 14.3 °C (e.g., areas orange red any any shade of pink) represented in Figure 1. Outdoor enthusiasts falling within areas highlighted yellow, orange, red or pink should wear DEET to protect against WNV! Historically, southern and central regions of the Canadian prairies are at increased risk for WNV from late July but typically peaks over the long weekend in August.

**Figure 1**. Predicted development of *Culex tarsalis* across the Canadian prairies (as of August 21, 2022).

For those following the specifics of the mosquito host-WNV interaction, Figure 2 projects how many days it will take a C. tarsalis female to become fully infective and be able to transmit the virus to another host (bird or human) once the virus is acquired from another bird. This represents the extrinsic incubation period (EIP) of the virus within the mosquito. Figure 2 projects the EIP was approximately 12-14 days in areas highlighted mauve and approximately 22-24 days in areas highlighted light green.

Figure 2. Predicted extrinsic incubation period (EIP) of West Nile Virus within a *C. tarsalis* female as of August 21, 2022.

The above maps should be compared with historical confirmed cases of WNV. The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date August 13, 2022; retrieved August 26, 2022) and provided below.

Bird surveillance continues to be an important way to detect and monitor West Nile Virus. The Canadian Wildlife Health Cooperative (CWHC) works with governmental agencies (i.e., provincial laboratories and the National Microbiology Laboratory) and other organizations to report the occurrence of WNV. Dead birds retrieved from areas of higher risk of West Nile Virus are tested for the virus. A screenshot of the latest reporting results posted by Canadian Wildlife Health Cooperative is below (retrieved 25Aug2022).

Anyone keen to identify mosquitoes will enjoy this pictorial key for both larvae and adults which is posted on the Centre for Disease Control (CDC) website but sadly lacks a formal citation other than “MOSQUITOES: CHARACTERISTICS OF ANOPHELINES AND CULICINES prepared by Kent S. Littig and Chester J. Stojanovich” and includes Pages 134-150. The proper citation may be Stojanovich, Chester J. & Louisiana Mosquito Control Association. (1982). Mosquito control training manual. pp 152.

West nile virus risk

As of August 14, 2022 and where present, C. tarsalis development has progressed. Remember, areas highlighted yellow have accumulated sufficient heat units for the second generation of C. tarsalis to fly. Many areas of the prairies well exceed the 250-300 DD of base 14.3 °C (e.g., areas orange red any any shade of pink) represented in Figure 1. Outdoor enthusiasts falling within areas highlighted yellow, orange, red or pink should wear DEET to protect against WNV! Historically, southern and central regions of the Canadian prairies are at increased risk for WNV from late July but typically peaks over the long weekend in August.

**Figure 1**. Predicted development of *Culex tarsalis* across the Canadian prairies (as of August 14, 2022).

For those following the specifics of the mosquito host-WNV interaction, Figure 2 projects how many days it will take a C. tarsalis female to become fully infective and be able to transmit the virus to another host (bird or human) once the virus is acquired from another bird. This represents the extrinsic incubation period (EIP) of the virus within the mosquito. Figure 2 projects the EIP was approximately 12-15 days in areas highlighted mauve and approximately 22-24 days in areas highlighted light green.

Figure 2. Predicted extrinsic incubation period (EIP) of West Nile Virus within a *C. tarsalis* female as of August 14, 2022.

The above maps should be compared with historical confirmed cases of WNV. The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date July 30, 2022; retrieved August 18, 2022) and provided below.

West nile virus risk

As of July 24, 2022, C. tarsalis development is now on the verge of the second generation of adults beginning to fly in areas highlighted yellow (i.e., 250-300 DD of base 14.3 °C) represented below in Figure 1. Outdoor enthusiasts falling within areas highlighted orange or yellow should begin to wear DEET to protect against WNV! Historically, southern and central regions of the Canadian prairies are now in a period of increased risk for WNV that typically peaks over the long weekend in August.

**Figure 1**. Predicted development of *Culex tarsalis* across the Canadian prairies (as of July 24, 2022).

For those following the specifics of the mosquito host-WNV interaction, Figure 2 projects how many days it will take a C. tarsalis female to become fully infective and be able to transmit the virus to another host (bird or human) once the virus is acquired from another bird. This represents the extrinsic incubation period (EIP) of the virus within the mosquito. Figure 2 projects the EIP is approximately 17 days in areas highlighted red and approximately 15 days in areas highlighted pink.

Figure 2. Predicted extrinsic incubation period (EIP) of West Nile Virus within a *C. tarsalis* female as of July 24, 2022.

The above maps should be compared with historical confirmed cases of WNV. The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date November 18, 2021; retrieved July 28, 2022). The screenshot below (retrieved 28Jul2022) serves as a background reference of what was reported in 2021.

West nile virus risk

As of July 17, 2022, C. tarsalis development is now on the verge of the second generation of adults beginning to fly in areas highlighted yellow (i.e., 250-300 DD of base 14.3 °C) represented below in Figure 1. Outdoor enthusiasts falling within areas highlighted orange or yellow should begin to wear DEET to protect against WNV! Historically, southern and central regions of the Canadian prairies are now entering a period of increased risk for WNV that typically peaks over the long weekend in August.

**Figure 1**. Predicted development of *Culex tarsalis* across the Canadian prairies (as of July 17, 2022).

Figure 2. Predicted extrinsic incubation period (EIP) of West Nile Virus within a *C. tarsalis* female as of July 17, 2022.

The above maps should be compared with historical confirmed cases of WNV. The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date November 18, 2021; retrieved July 20, 2022). The screenshot below (retrieved 20Jul2022) serves as a background reference of what was reported in 2021.

West nile virus risk

The following is offered to help predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies. By this week, all regions across the prairies have now accumulated sufficient degree-day heat units for Culex tarsalis to develop to adult stages, if present in the region (Fig. 1).

As of August 15, 2021 (Fig. 1), C. tarsalis development has now reached the point that adults are predicted to be flying across all areas of the Canadian prairies. Outdoor enthusiasts falling within areas highlighted red OR in areas that have accumulated >400 degree-days for C. tarsalis to emerge should wear DEET to protect against WNV!

**Figure 1**. Predicted development of *Culex tarsalis* across the Canadian prairies (as of August 15, 2021).

The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date August 13, 2021; retrieved August 19, 2021). The screenshot below (retrieved 19Aug2021) serves as a reference and reports one human case of WNV, two positive wild birds, and positive mosquito pools in Ontario.

West nile virus risk

As of August 8, 2021 (Fig. 1), C. tarsalis development has now reached the point that adults are predicted to be flying across the south of the prairies from Manitoba to Alberta. Outdoor enthusiasts falling within areas highlighted red (i.e., areas that have accumulated sufficient heat accumulation of >400 degree-days for C. tarsalis to emerge) should wear DEET to protect against WNV! Because of the continued high temperatures, areas highlighted yellow or orange in the map below (as of August 8) should also start to use DEET this week!

**Figure 1**. Predicted development of *Culex tarsalis* across the Canadian prairies (as of August 1, 2021).

The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date June 21, 2021; retrieved August12, 2021). The screenshot below (retrieved 12Aug2021) serves as a reference and reports one human case of WNV, a positive wild bird, and positive mosquito pools in Ontario.

West nile virus risk

As of July 25, 2021 (Fig. 1), C. tarsalis development has now reached the point that adults are predicted to be flying across the south of the prairies from Manitoba to Alberta. Outdoor enthusiasts falling within areas highlighted red (i.e., areas that have accumulated sufficient heat accumulation for C. tarsalis to emerge) should wear DEET to protect against WNV! Because of the continued high temperatures, areas highlighted yellow or orange in the map below (as of July 25) should also start to use DEET this week! IF C. tarsalis is present in an area where WNV is active, it may take as little as 14 days for adults to become fully infective with the current warm weather (Fig. 2).

**Figure 1**. Predicted development of *Culex tarsalis* across the Canadian prairies (as of July 25, 2021).

Figure 2. Predicted days for virulence of West Nile Virus to develop within *Culex tarsalis*, if present within a region (as of July 26, 2021).

The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date June 21, 2021; retrieved July 29, 2021). The screenshot below (retrieved 29Jul2021) serves as a reference and reports one human case of WNV, a positive wild bird, and positive mosquito pools in Ontario.

West nile virus risk

As of July 18, 2021 (Fig. 1), C. tarsalis development continues to be most advanced in southern Manitoba, southern Alberta, and southwestern Saskatchewan. Outdoor enthusiasts falling within areas highlighted red (i.e., areas that have accumulated sufficient heat accumulation for C. tarsalis to emerge) should wear DEET to protect against WNV! Because of the continued high temperatures, areas highlighted yellow or orange in the map below (as of July 18) should also start to use DEET this week! IF C. tarsalis is present in an area where WNV is active, it may take as little as 14 days for adults to become fully infective with the current warm weather (Fig. 2).

**Figure 1**. Predicted development of *Culex tarsalis* across the Canadian prairies (as of July 18, 2021).

The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date June 21, 2021; retrieved July 22, 2021). The screenshot below (retrieved 22Jul2021) serves as a reference and reports one human case of WNV in Ontario.

West nile virus risk

As of July 11, 2021 (Fig. 1), C. tarsalis development continues to be most advanced in Manitoba, southern Alberta, and in a small pocket in southern Saskatchewan. The map will change very quickly to red (i.e., areas with sufficient heat accumulation for C. tarsalis to emerge). Areas highlighted yellow or orange in the map below (as of July 11) should start to use DEET this week! IF C. tarsalis is present in an area where WNV is active, it may take as little as 12 days for adults to become fully infective with the current warm weather.

**Figure 1**. Predicted development of *Culex tarsalis* across the Canadian prairies (as of July 4, 2021).

The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date June 21, 2021; retrieved July 13, 2021). The screenshot below (retrieved 13Jul2021) serves as a reference.

West nile virus risk

As of July 4, 2021 (Fig. 1), C. tarsalis development is most advanced in Manitoba, southern Alberta, and in small pockets in southern Saskatchewan. The map will change very quickly to orange then red (i.e., areas with sufficient heat accumulation for C. tarsalis to emerge). Given the forecast, areas highlighted yellow in the map below (as of July 4) should start to use DEET this week! IF C. tarsalis is present in an area where WNV is active, it may take as little as 12 days for adults to become fully infective with the current warm weather.

The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date June 21, 2021; retrieved July 8, 2021). The screenshot below (retrieved 08Jul2021) serves as a reference.

West nile virus risk

Health Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access the most current weekly update (reporting date July 12-18, 2020; retrieved Aug 13, 2020). The screenshot below (retrieved Aug 13, 2020) serves as reference but access that Health Canada information here.

This image has an empty alt attribute; its file name is 2020Jun28-Jul04_WNV_Weekly_HealthCanada-1024x593.png

The following is offered to predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies (Fig. 1). This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in the map below (yellow, orange then red highlighted areas). As of August 9, 2020 (Fig. 1), areas highlighted yellow and more imminently orange are approaching sufficient heat accumulation for mosquitoes to emerge. Areas highlighted red NOW HAVE Culex tarsalis flying (Fig. 1) – protect yourself by wearing DEET!

**Figure 1**. Predicted development of *Culex tarsalis*, across the Canadian prairies (as of August 9, 2020).

West nile virus risk

Health Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access the most current weekly update (reporting date July 12-18, 2020; retrieved Aug 11, 2020). The screenshot below (retrieved Aug 11, 2020) serves as reference but access that Health Canada information here.

The following is offered to predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies (Fig. 1). This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in the map below (yellow, orange then red highlighted areas). As of August 5, 2020 (Fig. 1), areas highlighted yellow and more imminently orange are approaching sufficient heat accumulation for mosquitoes to emerge. Areas highlighted red NOW HAVE Culex tarsalis flying (Fig. 1) – protect yourself by wearing DEET!

**Figure 1**. Predicted development of *Culex tarsalis*, across the Canadian prairies (as of August 5, 2020).

West nile virus risk

Health Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access the most current weekly update (July 5-11, 2020; retrieved July 30, 2020). The screenshot below (retrieved July 30, 2020) serves reference but access that information here.

The following is offered to predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies (Fig. 1). This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in the map below (yellow, orange then red highlighted areas). As of July 30, 2020 (Fig. 1), areas highlighted yellow and more imminently orange are approaching sufficient heat accumulation for mosquitoes to emerge. Areas highlighted red NOW HAVE Culex tarsalis flying (Fig. 1) – protect yourself by wearing DEET!

**Figure 1**. Predicted development of *Culex tarsalis*, across the Canadian prairies (as of July 30, 2020).

West nile virus risk

Health Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access the most current weekly update (July 4, 2020; retrieved July 23, 2020). The screenshot below (retrieved July 23, 2020) serves reference but access that information here.

The following is offered to predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies (Fig. 1). This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in the map below (yellow, orange then red highlighted areas). As of July 19, 2020, areas highlighted yellow and more imminently orange are approaching sufficient heat accumulation for mosquitoes to emerge. Plan to protect yourself by wearing DEET!

**Figure 1**. Predicted development of *Culex tarsalis*, across the Canadian prairies (as of July 19, 2020).

West nile virus risk

Health Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access the most current weekly update (July 4, 2020). The screenshot below was retrieved 16Jul2020 as reference but access that information here.

The following is offered to predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies (Fig. 1). This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in the map below (yellow, orange then red highlighted areas). As of July 13, 2020, areas highlighted yellow and more imminently orange are approaching sufficient heat accumulation for mosquitoes to emerge. Plan to protect yourself by wearing DEET!

**Figure 1**. Predicted development of *Culex tarsalis*, across the Canadian prairies (as of July 13, 2020).

West nile virus risk

Health Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access the most current weekly update (July 4, 2020). The screenshot below was retrieved 09Jul2020 as reference but access that information here.

The following is offered to predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies (Fig. 1). This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in the map below. As of July 8, 2020, areas highlighted yellow are approaching sufficient heat accumulation for mosquitoes to emerge. Plan to protect yourself by wearing DEET!

**Figure 1**. Predicted development of *Culex tarsalis*, across the Canadian prairies (as of July 8, 2020).

West Nile Virus and Culex tarsalis

West Nile Virus Risk
Health Canada posts information related to West Nile Virus in Canada. Health Canada also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access the most current weekly update (August 10, 2019). The screenshot below was retrieved 22Aug2019 as reference but access that information here.

The following is offered to predict when Culex tarsalis will begin to fly across the Canadian prairies (Fig. 1). Protect yourself by wearing DEET! This week, regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. As of August 18, 2019, areas highlighted orange are on the verge of approaching sufficient heat accumulation for mosquitoes to emerge. Areas highlighted red in the map below should now have C. tarsalis in flight.

Once adults emerge, the following map demonstrates how quickly a Culex tarsalis mosquito carrying WNV can become fully infective (i.e., when it has accumulated 109 base 14.3° degree days) – it’s a matter of days, depending on the region (Figure 2). For example, as of August 18, 2019, areas highlighted orange in the map below had C. tarsalis flying that required 18-20 days to become fully infective.

West Nile Virus and Culex tarsalis

West Nile Virus Risk – Health Canada posts information related to West Nile Virus in Canada. Health Canada also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access the most current weekly update (August 3, 2019). The screenshot below was retrieved 15Aug2019 as reference but access that information here.

The following is offered to predict when Culex tarsalis will begin to fly across the Canadian prairies (Fig. 1). Protect yourself by wearing DEET! This week, regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. As of August 11, 2019, areas highlighted orange are on the verge of approaching sufficient heat accumulation for mosquitoes to emerge. Areas highlighted red in the map below should now have C. tarsalis in flight.

Once adults emerge, the following map demonstrates how quickly a Culex tarsalis mosquito carrying WNV can become fully infective (i.e., when it has accumulated 109 base 14.3° degree days) – it’s a matter of days, depending on the region (Figure 2). For example, as of August 11, 2019, Foremost AB was predicted to only take 16-18 days for C. tarsalis to become fully infective.

West Nile Virus and Culex tarsalis

West Nile Virus Risk – Health Canada posts information related to West Nile Virus in Canada. Health Canada also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access the most current weekly update (July 27, 2019). The screenshot below was retrieved 09Aug2019 as reference but access that information here.

The following is offered to predict when Culex tarsalis will begin to fly across the Canadian prairies (Fig. 1). Protect yourself by wearing DEET! This week, regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. As of July 28, 2019, areas highlighted orange are on the verge of approaching sufficient heat accumulation for mosquitoes to emerge. Areas highlighted red in the map below should now have C. tarsalis in flight.

Once adults emerge, the following map demonstrates how quickly a Culex tarsalis mosquito carrying WNV can become fully infective (i.e., when it has accumulated 109 base 14.3° degree days) – it’s a matter of days, depending on the region (Figure 2). For example, as of August 8, 2019, Winnipeg MB was predicted to only take 16-18 days for C. tarsalis to become fully infective.

West Nile Virus and Culex tarsalis

West Nile Virus Risk – Health Canada posts information related to West Nile Virus in Canada. Health Canada also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access the most current weekly update (July 20, 2019). The screenshot below was retrieved 01Aug2019 as reference but access that information here.

The following is offered to predict when Culex tarsalis will begin to fly across the Canadian prairies (Fig. 1). Protect yourself by wearing DEET! This week, regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. As of July 28, 2019, areas highlighted orange are on the verge of approaching sufficient heat accumulation for mosquitoes to emerge. Areas highlighted red in the map below should now have C. tarsalis in flight.

Once adults emerge, the following map demonstrates how quickly a Culex tarsalis mosquito carrying WNV can become fully infective (i.e., when it has accumulated 109 base 14.3° degree days) – it’s a matter of days, depending on the region (Figure 2). For example, as of July 28, 2019, Altona MB is predicted to only take 16 days for C. tarsalis to become fully infective!

West Nile Virus and Culex tarsalis

West Nile Virus Risk – Health Canada posts information related to West Nile Virus in Canada. Health Canada also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access the most current weekly update (July 13, 2019). The screenshot below was retrieved 25Jul2019 as reference but access that information here.

The following is offered to predict when Culex tarsalis will begin to fly across the Canadian prairies (Fig. 1). Protect yourself by wearing DEET! This week, regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. Areas highlighted yellow in the map below (Fig. 2) are on the verge of approaching sufficient heat accumulation for mosquitoes to emerge. Areas highlighted lime green should be preparing for C. tarsalis flight.

West Nile Virus and Culex tarsalis

West Nile Virus Risk – Reminder – In 2018, there were 426 human clinical cases of West Nile virus (WNV) in Canada (Fig. 1).

Figure 1. Geographic distribution of WNV human clinical cases and asymptomatic infections in Canada, 2018.
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (11Jul2019). Access the full map at https://www.canada.ca/en/public-health/services/publications/diseases-conditions/west-nile-virus-surveillance/2018/november-11-december-15-week-46-50.html

Health Canada posts information related to West Nile Virus in Canada. Health Canada also tracks WNV through human, mosquito, bird and horse surveillance. Link here to access the most current weekly update (July 6, 2019). The screenshot below was retrieved 18Jul2019 as reference but access that information here.

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus in birds. Take note of the provincial distribution of positive WNV birds in 2018 (table posted below as reference).

The following is offered to predict when Culex tarsalis will begin to fly across the Canadian prairies (Fig. 2). Protect yourself by wearing DEET! This week, regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. Areas highlighted yellow in the map below (Fig. 2) are on the verge of approaching sufficient heat accumulation for mosquitoes to emerge. Areas highlighted lime green should be preparing for C. tarsalis flight.

West Nile Virus and Culex tarsalis

West Nile Virus Risk – In 2018, there were 426 human clinical cases of West Nile virus (WNV) in Canada (Fig. 1).

Health Canada posts information related to West Nile Virus in Canada. Health Canada also tracks WNV through human, mosquito, bird and horse surveillance. Link here to access the most current weekly update (June 29, 2019). The screenshot below was retrieved 11Jul2019 as reference but access that information here.

The following is offered to predict when Culex tarsalis will begin to fly (Fig. 2) across the Canadian prairies. Protect yourself by wearing DEET! The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. Areas highlighted lime green in the map below (Fig. 2) are on the verge of approaching sufficient heat accumulation for mosquitoes to emerge soon.

Once the adults emerge, the following map demonstrates how quickly a Culex tarsalis mosquito carrying WNV can become fully infective (i.e., when it has accumulated 109 base 14.3° degree days) – as quickly as 20-22 days, given the current environmental conditions in the highlighted areas of the map below (Figure 3).

West Nile Virus and Culex tarsalis

West Nile Virus Risk – The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. Areas highlighted yellow then orange are approaching sufficient heat accumulation for mosquitoes to emerge while mosquitoes will be flying in areas in red so wear DEET to stay protected!

Health Canada posts information related to West Nile Virus in Canada. Health Canada also tracks WNV through human, mosquito, bird and horse surveillance. Link here to access the most current weekly update (July 7, 2018) on 2018 testing (screenshot retrieved 25Jul2018 provided below for reference only).

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus in birds. As of June 28, 2018, 872 birds were examined and nine have tested positive for West Nile virus. View a screen shot of the summary of those results below:

West Nile Virus and Culex tarsalis

Health Canada posts information related to West Nile Virus in Canada. Health Canada also tracks WNV through human, mosquito, bird and horse surveillance. Link here to access the most current weekly update (July 7, 2018) on 2018 testing (screenshot retrieved 25Jul2018 provided below for reference only).

Reminder – The 2017 WNV surveillance map for human cases is available here but a screenshot is posted below for reference.

Figure 1. As of surveillance week 49, ending December 9, 2017, the preliminary data indicated 197 human cases of WNV in Canada; twenty-five from Québec, 159 from Ontario, five from Manitoba, seven from Alberta, and one from British Columbia.

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus in birds. As of June 28, 2018, 642 birds were examined and zero have tested positive for West Nile virus.

West Nile Virus and Culex tarsalis

Health Canada posts information related to West Nile Virus in Canada. Health Canada also tracks WNV through human, mosquito, bird and horse surveillance. Link here to access the most current weekly update (June 30, 2018) on 2018 testing (screenshot retrieved 18Jul2018 provided below for reference only).

Reminder – The 2017 WNV surveillance map for human cases is available here but a screenshot is posted below for reference.

West Nile Virus and Culex tarsalis

Health Canada posts information related to West Nile Virus in Canada. Health Canada also tracks WNV through human, mosquito, bird and horse surveillance. The 2017 WNV surveillance map for human cases is available here but a screenshot is posted below for reference.

West Nile Virus and Culex tarsalis

West Nile Virus Risk – The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. As of August 20, 2017, areas highlighted in red on the map below have accumulated sufficient heat for C. tarsalis to fly. Culex tarsalis are also flying in areas highlighted in red, pink or mauve so wear your DEET to stay protected! Areas highlighted orange or yellow in the map should also be preparing for C. tarsalis flight.

The Public Health Agency of Canada posts information related to West Nile Virus in Canada. The map of clinical cases of West Nile Virus in Canada in 2017 is updated through the summer (screen shot of map below). The Public Health Agency of Canada (PHAC), as of August 12, 2017, reported eight clinical cases (confirmed or probable) in Ontario and one asymptomatic infection in British Columbia. All eight cases from ON are currently unclassified and two were travel-related.

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus in birds. As of August 24, 2017, 1218 birds were examined and 58 tested positive for West Nile virus; three from Saskatchewan, two from Manitoba, 15 from Ontario, and 38 from Quebec.

The Public Health Agency of Canada also monitors and posts updates on the status of WNV in Mosquitoes. As of August 12, 2017, Quebec, Ontario, Manitoba and Saskatchewan reported positive mosquito pools for West Nile Virus.

A total of 224 positive mosquito pools have been found:

172 from Ontario [Brant County (2), Chatham-Kent (3), Durham Region (4), Eastern Ontario (3), Halton Region (15), Hamilton (4), Haliburton-Kwartha-Pine Ridge District (1), Hastings and Prince Edward Countries (7), Kingston-Frontenac and Lennox and Addington (2), Lambton (1), Middlesex-London (3), Niagara Region (7), Ottawa (11), Oxford County (1), Peel (40), Perth District (2), Peterborough County-City (1), Renfrew County and District (2), Simcoe Muskoka District (1), Toronto (31), Waterloo (2), Wellington-Dufferin-Guelph (2), Windsor-Essex County (21), and York Regional (6)];
35 from Manitoba [(Winnipeg (12), Southern (4), Interlake Eastern (5), and Prairie Mountain (12)];
9 from Quebec [Montérégie (6), Laval (1), and Mauricie-centre-du-Québec(2)];
8 from Saskatchewan.

West Nile Virus and Culex tarsalis

West Nile Virus Risk – The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. As of August 13 2017, areas highlighted in red on the map below have accumulated sufficient heat for C. tarsalis to fly. Areas highlighted in red, orange and even yellow will have C. tarsalis flying so wear your DEET to stay protected!

The Public Health Agency of Canada posts information related to West Nile Virus in Canada. In 2016, 104 human clinical cases of West Nile Virus were reported. The map of clinical cases of West Nile Virus in Canada in 2017 is updated through the summer and three cases of viral West Nile have been reported so far (as of August 5, 2017). All cases were reported from Ontario (in Timiskaming and Windsor-Essex).

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus in birds. As of August 17, 2017, 1113 birds were examined and 48 have tested positive for West Nile virus; one from Saskatchewan, two from Manitoba, 13 from Ontario, and 32 from Quebec.

The Public Health Agency of Canada also monitors and posts updates on the status of WNV in Mosquitoes. As of July 22, 2017, Quebec, Ontario, Manitoba and Saskatchewan have reports of positive mosquito pools of West Nile Virus. A total of 47 positive mosquito pools have been found:

33 from Ontario [Peel Regional (5), Toronto (6), Halton(5), Haliburton-Kwartha-Pine Ridge District(1), Simcoe Muskoka District (1), Windsor-Essex County (6), Eastern Ontario (1), Durham Reginal (1), Hamilton (1), Haliburton-Kawarta-Pine Ridge district (1), Hastings and Prince Edward Countries (2), and York Regional (3)];
11 from Manitoba [(Winnipeg (3), Southern (2), Interlake eastern (1), and Prairie Mountain(5)];
2 from Quebec [Montérégie (1), Laval (1)], and
1 from Saskatchewan.

West Nile Virus and Culex tarsalis

West Nile Virus Risk – The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. As of July 30, 2017, areas highlighted in red on the map below have accumulated sufficient heat for C. tarsalis to fly. Areas highlighted in red, orange and even yellow will have C. tarsalis flying so wear your DEET to stay protected!

The Public Health Agency of Canada posts information related to West Nile Virus in Canada. In 2016, 104 human clinical cases of West Nile Virus were reported. The map of clinical cases of West Nile Virus in Canada in 2017 is updated through the summer and two cases of viral West Nile have been reported so far (as of July 22, 2017). Both cases were reported from Ontario (in Timiskaming and Windsor-Essex).

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus in birds. As of August 3, 2017, 964 birds were examined and 23 have tested positive for West Nile virus; two from Manitoba, eight from Ontario, and 13 from Quebec.

The Public Health Agency of Canada also monitors and posts updates on the status of WNV in Mosquitoes. As of July 22, 2017, Quebec, Ontario, Manitoba and Saskatchewan have reports of positive mosquito pools of West Nile Virus. A total of 47 positive mosquito pools have been found:

33 from Ontario [Peel Regional (5), Toronto (6), Halton(5), Haliburton-Kwartha-Pine Ridge District(1), Simcoe Muskoka District (1), Windsor-Essex County (6), Eastern Ontario (1), Durham Reginal (1), Hamilton (1), Haliburton-Kawarta-Pine Ridge district (1), Hastings and Prince Edward Countries (2), and York Regional (3)];
11 from Manitoba [(Winnipeg (3), Southern (2), Interlake eastern (1), and Prairie Mountain(5)];
2 from Quebec [Montérégie (1), Laval (1)], and
1 from Saskatchewan.

Weekly Update – West Nile Virus and Culex tarsalis

West Nile Virus Risk – The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. As of July 23, 2017, areas highlighted in yellow on the map below have accumulated sufficient heat for the initial C. tarsalis to begin to fly. Areas highlighted in orange will have C. tarsalis flying so wear your DEET to stay protected!

The Public Health Agency of Canada posts information related to West Nile Virus in Canada. In 2016, 104 human clinical cases of West Nile Virus were reported. The map of clinical cases of West Nile Virus in Canada in 2017 is updated through the summer but zero cases of viral West Nile have been reported so far (June 25-July 15, 2017).

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus in birds. As of July 20, 2017, 833 birds were examined and eight have tested positive for West Nile virus; four from Ontario, one from Saskatchewan, and one from Quebec.

West Nile Virus and Culex tarsalis

West Nile Virus Risk – The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. As of July 13, 2017, areas highlighted in yellow on the map below have accumulated sufficient heat for the initial C. tarsalis to begin to fly whereas areas highlighted in orange have to C. tarsalis flying so wear your DEET to stay protected!

The Public Health Agency of Canada posts information related to West Nile Virus in Canada. In 2016, 104 human clinical cases of West Nile Virus were reported. The map of clinical cases of West Nile Virus in Canada in 2017 is updated through the summer but zero cases of viral West Nile have been reported so far (June 25-July 1, 2017).

West Nile Virus and Culex tarsalis

West Nile Virus Risk – The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. As of July 9, 2017, areas highlighted in yellow on the map below have accumulated sufficient heat for C. tarsalis to fly so wear your DEET to stay protected!

The Public Health Agency of Canada posts information related to West Nile Virus in Canada. In 2016, 104 human clinical cases of West Nile Virus were reported. The map of clinical cases of West Nile Virus in Canada in 2017 is updated through the summer but zero cases of viral West Nile have been reported so far (June 25-July 1, 2017).

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus in birds. As of July 6, 2017, 729 birds were examined and six have tested positive for West Nile virus in Ontario.

Weekly Update – West Nile Virus and Culex tarsalis

West Nile Virus Risk – The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. As of August 21, 2016, areas highlighted in yellow, orange, or red on the map below have accumulated sufficient heat for C. tarsalis to fly so wear your DEET to stay protected!

The Public Health Agency of Canada posts information related to West Nile Virus in Canada. The map of clinical cases of West Nile Virus in Canada in 2016 is posted (as of July 23, 2016) while a screen shot is provided below (posted August 22, 2016).

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus. As of August 22, 2016, 36 birds were submitted for testing and two have tested positive for West Nile virus in Ontario.

Weekly Update – West Nile Virus and Culex tarsalis

West Nile Virus Risk – The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. As of August 14, 2016, areas highlighted in yellow, orange, or red on the map below have accumulated sufficient heat for C. tarsalis to fly so wear your DEET to stay protected!

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus. As of August 17, 2016, 32 birds were submitted for testing yet none have tested positive for West Nile virus.

Weekly Update – West Nile Virus and Culex tarsalis

West Nile Virus Risk – The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. As of August 7, 2016, areas highlighted in yellow, orange, or red on the map below have accumulated sufficient heat for C. tarsalis to fly so wear your DEET to stay protected!

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus. As of August 3, 2016, 27 birds were submitted for testing yet none have tested positive for West Nile virus.

Weekly Update – West Nile Virus and Culex tarsalis

West Nile Virus Risk – The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. As of July 31, 2016, areas highlighted in yellow, orange, or red on the map below have accumulated sufficient heat for C. tarsalis to fly so wear your DEET to stay protected!

Weekly Update – West Nile Virus and Culex tarsalis

West Nile Virus Risk – The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. As of July 24, 2016, areas highlighted in yellow, orange, or red on the map below have accumulated sufficient heat for C. tarsalis to fly so wear your DEET to stay protected!

The Public Health Agency of Canada posts information related to West Nile Virus in Canada. The map of clinical cases of West Nile Virus in Canada in 2015 is posted while a screen shot is provided below.

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus. As of July 27, 2016, 27 birds were submitted for testing yet none have tested positive for West Nile virus.

Weekly Update – West Nile Virus and Culex tarsalis

West Nile Virus Risk – The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. As of July 17, 2016, areas highlighted in yellow or orange on the map below have accumulated sufficient heat for C. tarsalis to fly so wear your DEET to stay protected!

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus. As of July 7, 2016, 20 birds were submitted for testing yet none have tested positive for West Nile virus.