The Manitoba government has ordered mosquito fogging in Morden and Boissevain after surveillance detected elevated numbers of the mosquito species that carries West Nile virus and signs that some insects may be infected.
Where fogging will take place
In an update issued Thursday, provincial officials said last week's data showed high counts of adult Culex tarsalis — the species associated with West Nile transmission — and evidence of mosquitoes infected with the virus. So far this year, the province has not confirmed any human cases of West Nile virus.
The two newly added locations and the areas affected are:
- Morden: the city and a radius of about 3 kilometres into the Rural Municipality of Stanley.
- Boissevain: the town and an area extending roughly 3.5 kilometres from the intersection of Highway 10 and North Railway Street, in the Municipality of Boissevain-Morton.
Earlier this week the province said it would begin fogging in Carman, Stonewall and Winkler, along with the Rural Municipality of West St. Paul and parts of Winnipeg. Some fogging has already taken place in those locations, and additional rounds were scheduled for Carman, Stonewall and West St. Paul on days the provincial website lists as either Friday or Saturday.
What officials say and what’s known
Provincial health and environment authorities cited monitoring results as the reason for expanding the fogging program. The announcement did not include specific dates for fogging in Morden and Boissevain; the province said the timing will be posted on its website when available.
The decision follows routine mosquito surveillance that measures both abundance and the presence of West Nile virus in trapped insects. When mosquito counts exceed established thresholds or when infected mosquitoes are detected, public-health responses such as fogging are triggered to reduce adult mosquito populations in targeted areas.
Areas previously targeted
| Community | Recent status |
|---|---|
| Carman | Fogging announced; some treatments already completed |
| Stonewall | Fogging announced; some treatments already completed |
| Winkler | Fogging announced; some treatments already completed |
| R.M. of West St. Paul | Fogging announced; additional treatments scheduled |
| Parts of Winnipeg | Targeted fogging in specific neighbourhoods |
Local impact and context
Fogging is one of several tools public-health and municipal authorities use to reduce nuisance and potentially infected adult mosquito populations during the summer months. The move to expand fogging reflects surveillance indicating a higher-than-normal presence of the particular mosquito species known to spread West Nile virus.
To date, Manitoba has not recorded any human West Nile virus infections this season. However, the presence of infected mosquitoes in traps signals an increased risk that warrants local control measures, particularly in populated areas where mosquito abundance has exceeded provincial thresholds.
Residents in the affected communities should watch the province’s website for announcements on exact fogging dates and any local advisories. The government has said those details will be posted when they are final.
What to expect next
Provincial monitoring will continue across Manitoba for mosquito abundance and infection rates. Authorities will base further responses — including additional fogging in other communities — on ongoing surveillance results.
- Fogging dates for Morden and Boissevain have not yet been announced.
- No human West Nile cases have been confirmed in Manitoba this year.
- Other communities have already undergone or been scheduled for fogging following the same surveillance triggers.
As more information becomes available, the province will update its public-facing pages. Local public-health units and municipal offices typically also post notices for residents about timing and any temporary measures tied to fogging operations.
Reporting from communities across southern Manitoba continues as officials and residents monitor mosquito activity through the rest of the summer.
