SUBMITTED BY:
Environmental Health
DATE:
March, 2022
SUBJECT:
Zoonotic and Vector-borne Diseases Report
BACKGROUND
The Environmental Health Department conducts annual monitoring and testing of tick and mosquito populations in Windsor and Essex County (WEC) as part of the Windsor- Essex County Health Unit’s (WECHU) Zoonotic and Vector-borne Diseases Program. The program is required under the Health Protection and Promotion Act and provides the community with an early warning system for disease transmission through ticks and mosquitoes known as vector-borne diseases. Due to our geography and local climate, the WEC region is more susceptible to vector-borne diseases, as the ecological conditions influence transmission and distribution.
Upon the completion each VBD program season, the WECHU prepares an annual report which highlights surveillance information related to Lyme disease and West Nile Virus (WNV) Illness in WEC. The 2021 Annual VBD report is available on our website Vector-Borne Diseases - WE - 2021 and a high level summary of these findings is included below.
Ticks and Lyme Disease
In the last three years, surveillance data indicated an increase in black-legged ticks (Ixodes scapularis) in WEC. The black-legged tick is the primary vector for Borrelia burgdorferi, the bacteria that causes Lyme Disease. Environmental Health staff conduct active field surveillance at public parks and trails frequently used by residents twice a year to identify areas in WEC that have populations of black-legged ticks.
In 2021, active surveillance was conducted at four sites that included,
- Ojibway Prairie Nature Reserve,
- Chrysler Greenway,
- Gesstwood Camp and Education Centre and
- Ruscome Shores Conservation Area
A total of 33 black-legged ticks were found through tick dragging, with nine of these carrying the infectious agent that causes Lyme disease.
In 2021, there were seven cases of Lyme Disease in WEC. All laboratory-confirmed cases are interviewed to determine activities and locations where exposure may have occurred. This information drives targeted tick awareness initiatives from the health unit.
Mosquito Surveillance and Testing
The WECHU has one of Ontario’s most comprehensive mosquito surveillance programs, including the West Nile Virus Program and Enhanced Mosquito Surveillance initiatives. In 2021, mosquito surveillance began in May and ended in early October. Species-specific traps were deployed in various locations throughout WEC to capture mosquitoes for testing and identification to determine the presence of West Nile, Eastern Equine Encephalitis (EEE) Virus, and Zika Virus in our region. Invasive mosquito species Aedes aegypti (Yellow Fever Mosquito) and Aedes albopictus (Asian Tiger Mosquito) were also monitored. These species are known carriers of Zika, Dengue, and Chikungunya diseases. The health unit monitors mosquitoes at different stages in their life cycle to determine prevention and control initiatives for the program.
In 2021, the weekly mosquito surveillance data is available on the WECHU’s Mosquito Surveillance Dashboard. The data is updated weekly during the season and is open to the public. During last year’s season:
- Total number of traps deployed per week: 47
- Total number of mosquitoes trapped: 187,918
- Total number of pools tested: 2,291
- Number of positive pools for West Nile virus : 17
- Number of positive pools for Zika virus: 0
- Number of positive pools for EEE virus: 0
Positive pools for WNV were reported in the following municipalities: City of Windsor (11), Town of Essex (3), Municipality of Leamington (2), and the Town of Amhestburg (1).
Over 118,000 treatments of larvicide were applied to roadside catch basins and standing water sites last year to control mosquito populations. All municipalities in WEC have standing water by-laws that municipalities enforce that are an important activity to reduce breeding habitats. Furthermore, property standards enforcement from municipalities continues to be a key factor in controlling invasive mosquito populations in our region, as these mosquitoes are container breeders (mosquitoes that lay eggs in containers).
The WECHU follows up on all reported human cases of WNV. Cases are investigated to assess if additional targeted mosquito control activities are required. In 2021, there were three confirmed cases of WNV in WEC. There have been no human cases of Zika Virus identified in our community to date.
CURRENT INITIATIVES
As previously reported, the WECHU was the successful receipient of the Public Health Agency of Canada’s grant (August 2019 – March 2022) to study the effects of climate change and mosquito populations in our local communities. The final report for the project will be released in March and will include information regarding the types of mosquito species (including invasive species) in the region, the impact of climate change on mosquito-borne diseases, and information regarding the populations in our community that are more vulnerable to these health impacts. The WECHU will begin surveillance and monitoring activities for ticks and mosquitoes in May 2022. In addition to these activities, the WECHU will be launching our annual Fight the Bite public awareness campaign. This campaign will focus on the prevention of mosquito breeding sites, information on tick removal, signs and symptoms of WNV and Lyme disease, and personal protection. Messages and promotional materials will be developed to reach priority populations and inform the public of hot spots identified through previous monitoring efforts.