Mosquito Control When Birds Bring West Nile virus.

Posted by Rosemary Drisdelle Jul 7, 2006

Have you read my article West Nile and Birds on birds and their role in spreading West Nile virus in North America? Mosquitoes bite infected birds and catch the virus, then bite people and pass it on. When sentinel birds such as Crows and Blue Jays start dying off in an area, local health officials know that they should start looking out for West Nile virus. Some municipalities test dead birds for the virus, while others trap and test mosquitoes.

The public health response to the presence of West Nile usually involves alerting and educating the public, and some form of mosquito control. Often, the advisability of spraying an area with insecticides is debated, and the debate can get quite spirited. Some people are comfortable spraying with insecticides that are considered safe for people and wildlife, citing the number of cases of West Nile fever, West Nile encephalitis, and death that are sure to occur otherwise.

On the other side of the debate, however, strong arguments against spraying exist:

• There is mounting evidence that insecticides are not safe. They threaten human health and harm wildlife, including birds and beneficial insects that would otherwise prey on mosquitoes and their larvae.
• Spraying in urban areas is ineffective because it's impossible to properly spray inside buildings and other structures.
• Spraying doesn't kill all the mosquitoes. Those that survive may develop resistance to the chemical.
• People develop a false sense of security when their community has been sprayed, and become careless about protecting themselves from insect bites.
• The response is out of proportion to the risk: many more people die from influenza than from West Nile virus.

If the sentinel birds started dying in your municipality, what response would you support? Do my poll on the Birds page from July 7 to July 17, 2006.