Mosquito traps in north London test positive for West Nile Virus

Local health officials are advising residents to take precautionary steps to prevent bug bites after two traps in London were found with West Nile Virus-positive mosquitoes.

On Monday, the Middlesex London Health Unit (MLHU) said the traps set up at locations in northwest and northeast London were recently tested and they are the first to be found with the disease in 2023.

“With the considerable rainfall this summer, leading to escalated mosquito breeding and elevated populations in certain areas, it is important to exercise caution and ensure the safety of both yourself and your loved ones against mosquito bites,” said Safe Water, Rabies and Vector Borne Disease Manager Andrew Powell.

Since the start of May, the MLHU said its Vector Borne Disease team have conducted weekly monitoring on the 23 adult mosquito trapping sites, and will continue efforts through September. Workers have conducted 451 treatments at 185 surface water locations.

“The Vector-Borne Disease Team is currently on the third round of catch basin treatment where approximately 35,000 catch basins are treated per round,” read a media statement from MLHU. “The Health Unit will continue its surveillance and control efforts throughout the region.”

Individuals are advised to protect themselves from West Nile Virus by wearing light-coloured clothing with long sleeves, pants and socks and use an insect repellent with DEET in areas where mosquitoes are present, especially at dusk and dawn when the insects are most active.

Residents should regularly empty standing water from outdoor items such as garbage cans, wheelbarrows, toys, flowerpots and saucers, pool covers, tires, and other items around your home and yard.

Most people (approximately 80 per cent) who are bitten by a West Nile Virus positive mosquito will have no symptoms. Government studies indicate that when infection does occur, it can cause mild illness such as headache, body aches, mild rash, swollen lymph glands. The effects may start to appear within two to 15 days. Symptoms can vary, and in serious cases, can affect the brain and spinal cord.

More information about West Nile Virus can be found on the health unit’s website at

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