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Mosquitoes, DDT, and repellent bloggers

By Michael Fumento

Deltoid's Tim Lambert, a blogger whose ranking has been dropping dramatically over the last year, has a vendetta against me because I've repeatedly made him look like a fool. That's so unfair; after all, making him look like a fool is like shooting blue whales in a coffee cup. His latest attack goes back to my piece at the beginning of year regarding the awful South Asian tsunami in which I noted the possibility of pestilence and said that, using the section Lambert lambastes, "The best answer would be spraying with DDT. Unfortunately, environmentalists have demonized DDT based essentially on unfounded accusations in a 1962 book, Silent Spring. DDT should be sprayed on water pools, tents, and on people themselves -- as indeed was once common in Sri Lanka and throughout most of the world."

Lambert quotes from a WHO report that, "Endemic sporadic malaria close to the affected areas transmitted by [the mosquito] An.culicifacies, which has been considered DDT-resistant for many years, but is still sensitive to organophosphates, such as malathion, and pyrethroids." Comments Tiny Tim, "Yes, the mosquitoes in Sri Lanka have evolved resistance to DDT. It doesn't work any more."

Being a little insect himself, you'd think he'd know a bit more about this. Resistance doesn't mean "immunity." Often it simply means using more insecticide in the spray than you would otherwise. It's the same with antibiotic resistance. Further, because resistance is a drain on an insect's physiology, after a time that resistance begins to fade. It has certainly been long enough since mosquitoes in those areas were sprayed with DDT that many will have lost resistance. But there's more yet.

Mosquitos "are almost certainly not going to become immune to DDT's most valuable attribute: its repellency," writes DDT expert Paul Driessen. Even in tiny quantities "DDT keeps up to 90% of the mosquitoes from even entering a home. It irritates those that do come in, so they don't bite; and it kills any that land on the walls, before they can infect another person. No other insecticide, at any price, can do that or do it for six months or more with a single application."

He knows whereof he speaks: The Journal of Vector Borne Diseases last June concluded: "The overall results of the study revealed that DDT is still a viable insecticide in indoor residual spraying owing to its effectivity in well supervised spray operation and high excito-repellency factor."

Now, you'd think that if there were one thing Lambert would know about it would be repellency.

October 19, 2005 10:57 AM  ·  Diseases (other than AIDS and cancer)