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No Spray News

James Irwin
PO Box 6393
Columbia, SC  29260


May 21, 2002      Page 3

When Is Spraying Recommended Against WNV?
Cornell's Lois Levitan Finds a Shift away from Spraying

   In most localities the initial panic that led to plans for using pesticides to kill mosquitoes within 2 miles of any WN'V detection have evolved into more prudent plans to use pesticides only when infection in the human population is detected or suspected. This is the gist of the current advisories from the federal Centers for Disease Control and from the NYS Department of Health. There is widespread consensus that the most effective offensive is prevention.

  and in a later update ...

   The word I have been hearing from most of the mosquito entomologists at the NYS DOH, as well as the tune of official publications defining prevention and control protocols, is strong emphasis on prevention and caution against considering use of pesticides unless there is immediate threat to human health. What defines this threat, and what to do when it exists, are of course not clear cut.

- What's Going on with the West Nile Virus, Update 2001 Lois Levitan


Just Say No?

  Some scientists (e.g., entomologist David Pimental of Cornell U., public health specialist and Michael Gotchfeld of Robert Wood Johnson Medical School) question the value of spraying for West Nile virus altogether.


Control Sooner Rather Than Later
                      -and spray as a last resort

   ...Waiting until after human transmission starts before controlling vectors is "closing the barn door ...... and is a situation to be avoided. At that point adult control might still be appropriate if further transmission is likely, but much of the damage has already been done, since human cases are not detected until some weeks after exposure. The ideal is to prevent exposure by protective measures (screens, etc.) and by larval control. If that works well, you might not see human illness, and people may wonder what the fuss was about. Should virus appear in mosquitoes, one should control them before human exposure. realizing it will be impossible to know if zero, 1 or dozens of illnesses will be prevented.

Posted by: Ninivaggi, Dominick
Suffolk County (NY) Mosquito Control


The Tiger Mosquito - The South's Complicating Factor

    Tests by U.S. Army researcher Michael Turell have found the tiger mosquito to be a very competent vector of West Nile virus which becomes infective quickly (4 days after exposure). If these results hold up, they could complicate dealing with WNV outbreaks in the Southern U.S., since spraying is not effective against the tiger mosquito. A lot depends on how often the tiger mosquito (which prefers to bite people, pets, and other mammals) actually bites the birds which can serve as reservoirs of WNV.

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