PREPARED BY: Environmental Health
DATE: December 5, 2024
SUBJECT: Seasonal Program Summary Report
BACKGROUND/PURPOSE
The WECHU delivers various seasonal programs that are mandated under the Ontario Public Health Standards. These programs include monitoring beach water quality, mosquito surveillance for West Nile Virus (WNV), Eastern Equine Encephalitis (EEE), Zika Virus, and tick surveillance for Lyme disease activity in Windsor and Essex County (WEC). This report provides a summary of the program outcomes for the 2024 season.
DISCUSSION
Beach Monitoring Program: The program ran for a total of 15 weeks from May 22 to August 28, 2024. Eight public beaches were monitored throughout the season with weekly water samples collected to test for the harmful bacteria indicator E. coli.
There were 27 water quality warnings issued (201-999 E. coli/100ml), and 9 beach closures (≥1000 E. coli/100ml). One warning was issued for blue green algae bloom observed at the Lakeshore Lakeview Park West Beach. This season had more water quality issues when compared with 2023, which had 20 warnings and 3 closures.
| Name of Beach | Warnings | Closures |
|---|---|---|
| Cedar Beach | 3 | 0 |
| Cedar Island Beach | 2 | 0 |
| Colchester Beach | 5 | 1 |
| Holiday Beach | 4 | 4 |
| Lakeshore Lakeview Park W. Beach | 3 | 2 |
| Point Pelee North West Beach | 2 | 0 |
| Sandpoint Beach | 4 | 2 |
| Seacliff Beach | 4 | 0 |
| TOTAL | 27 | 9 |
Mosquito Surveillance program: The program ran for a total of 20 weeks from May 22 to October 11, 2024. Once a week, 37 mosquito traps (23 CDC light traps and 14 BGS-2 traps) were set up across WEC to collect mosquitoes for identification and viral testing.
- Number of mosquitoes caught – 600,003
- Number of pools tested – 1014
- Number of WNV positive pools – 8
- Number of WNV human cases – 7
- Number of Aedes albopictus caught – 102
In 2024 there was an increase in the number of WNV human cases compared to one case in 2023 and two cases in 2022.
During week 26, the WECHU responded to a disproportionate number of mosquitoes caught in traps located in one WEC municipality, 53% of all mosquitoes trapped were found in this municipality. This was twice as many per trap on average compared with other municipalities. The WECHU took a proactive approach in collaboration with the municipal administration to enhance social media communications encouraging residents to follow the health units “Fight the Bite!” messaging to protect themselves against mosquito bites and remove standing water from their property.
There were no positive pools or human cases for EEE or Zika identified this year.
Mosquito larviciding program: Mosquito larviciding involves applying larvicides to catch basins, standing water sites, and lagoons that hold water where mosquitoes may breed. The WECHU and municipalities contracted a service provider to conduct larval surveillance beginning in May.
In 2024, 133,900 roadside catch basins (3 Phases) were treated across WEC. In response to the increased number of positive mosquito pools and their close proximity to the confirmed WNV human cases an additional 12,503 catch basins were treated in hot spot areas to reduce mosquito activity.
Active Tick Surveillance: Active surveillance is used to assess the local distribution and incidence of black-legged ticks in WEC. It involves the dragging of a white cloth through grassy areas whereby ticks attach themselves to the fabric and can be easily spotted and identified. Any black-legged ticks identified are sent to an accredited laboratory for testing for Lyme disease.
In 2024, active tick dragging was conducted at 2 sites across WEC (Ruscom Shores Conservation Area and Cipher Systems Green Way – Essex) in October. No blacklegged ticks were found through tick dragging this year.
As of November 15, 2024, there were 17 human cases of Lyme disease reported in WEC, this a significant increase compared to 9 cases in 2023 and 11 cases in 2022. Lyme disease is an infection transmitted through the bite of an infected blacklegged tick. Most human cases occur as a result of exposure to areas known to have infected blacklegged ticks. Early symptoms may include fever, headache, muscle and joint pain, fatigue and an expanding red rash. The best prevention is to avoid tick bites by using insect repellent, wearing proper clothing, removing ticks as soon as possible after bites and removing tick habitats from around the home. The WECHU is investigating the reported cases from this year and developing a comprehensive preventative strategy including an evidence informed enhancement to our active surveillance activities and awareness messaging for the 2025 season.