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Tuesday, August 22, 2017 | 11 a.m. | Windsor-Essex County

Photo of Aedes aegypti mosquito - credit CDC/James Gathany

An adult Aedes aegypti mosquito has been found in Windsor in a single mosquito trap. This is the first time that an adult Aedes aegypti mosquito has been captured in Canada. Last year, Aedes aegypti larvae were found in the region through enhanced mosquito surveillance. This discovery of adult Aedes aegypti, along with last week’s discovery of the 2 adult Aedes albopictus mosquitoes, indicates that the Aedes species may be starting to become established in the region.

Commonly known as the yellow fever mosquito, the Aedes aegypti is responsible for the majority of human cases of Zika virus infections in the Caribbean, South America and Florida. In addition, these introduced Aedes mosquitoes can also cause Dengue fever and Chikungunya. Last year, collected larvae in the Windsor area were identified and reared, with a total of three adult Aedes aegypti mosquitoes visually confirmed. This year’s adult mosquito was also analyzed in a laboratory. All Aedes aegypti mosquitoes found have tested negative for Zika virus and West Nile virus.

In the United States, the Aedes aegypti mosquito primarily exists in the southern states and along the eastern seaboard, where temperatures are more favourable for its survival. There are records of this mosquito being found in some northern states, including Michigan and New Hampshire; however, these were only temporary summer incursions, as the relatively cold winters prevented establishment.  It is unknown exactly how the mosquitoes arrived in Ontario. One possibility is that they were transported from the U.S. in shipping containers or other cross-border vehicle traffic.

“We will continue to ensure that our community stays informed about infectious diseases and our local mosquito surveillance program. The discovery of the adult Aedes aegypti mosquito is an important reminder that we should continue to protect ourselves and our families from mosquito bites. With these Aedes species found in the area, I urge residents to remove all standing water from their homes and work,” said Dr. Ahmed, Acting Medical Officer of Health, Windsor-Essex County Health Unit. 

The biting behaviour of the Aedes aegypti is different than those that transmit West Nile Virus in Ontario. It is a sneaky, human, daytime biter; it tends to approach humans from behind and bite them on the elbows and ankles. Like the Aedes albopictus, these mosquitoes do not breed in ponds, puddles or marshes. They typically lay eggs in and near standing water in items such as buckets, bowls, animal dishes, flower pots and vases. It is important to change water regularly, especially in pet dishes and water in bird baths.

For Zika virus transmission to occur, the Aedes aegypti mosquito would need to feed on an infected person, within the first several days of infection, and then feed upon another susceptible person. The greatest risk to contracting Zika virus continues to be centred on those who have travelled to Zika-risk areas (such as South America, the Caribbean and Florida) or who are or have been in sexual contact with these travellers.

While there is no change in risk for Zika virus in our community, it is still important to protect yourself and your family from mosquito bites. Until the first freeze hits, we are still at risk for West Nile virus and need to continue protecting ourselves. Individuals can do so in several ways:

  • Use insect repellents that contain DEET, Icaridin or other approved ingredients on clothing as well as exposed skin. Always read and follow label directions.
  • Wear long-sleeved shirts, long pants, and a hat when outdoors. Light-coloured clothing is best as mosquitoes tend to be attracted to dark colours.
  • Make sure that door and window screens fit securely and are free of holes.

The Windsor-Essex County Health Unit continues to conduct enhanced mosquito surveillance and is working closely with the Ministry of Health and Long-Term Care, Public Health Ontario, and the Public Health Agency of Canada to determine the best course of action moving forward. A media conference will be scheduled in the near future to share the next steps in controlling these Aedes species in our region.

Based on all we know about this mosquito and the absence of Zika virus in the tested mosquitoes and in our community, we conclude that there has not been nor is there current risk of local mosquito Zika virus transmission in Windsor-Essex County.  Furthermore, on the basis of all we know, we would recommend no additional Zika virus testing for Windsor-Essex County residents beyond the current guidelines.

Media Contact
Communications Department
Windsor-Essex County Health Unit
519-258-2146 ext. 6397 (NEWS)
news@wechu.org