Malaria, yellow fever, dengue fever are increasing so rapidly that DDT is returning.
Malaria accounts for nearly 90 percent of all deaths from vector-borne disease globally. And it is surging in Africa, surpassing AIDS as the biggest killer of African children under age 5.
At least 80 percent of human infectious diseases are transmitted by bugs. More than 3,000 species of mosquitoes have been the worst of all the disease carriers.
But now DDT is not used to kill a mosquito but to keep it away, a so called non-contact repellent action of DDT.
When DDT sprayed on the walls of huts in Thailand, three out of every five test mosquitoes sensed the presence of DDT molecules and would not enter the huts. Many of those that did enter and made contact with DDT became irritated and quickly flew out.
“Indoor DDT spraying to control malaria in Africa is supported by the World Health Organization; the Global Fund to Fight AIDS, Tuberculosis and Malaria; and the United States Agency for International Development.
“The remaining concern has been that the greater use of DDT in Africa would only lead mosquitoes to develop resistance to it. Decades ago, such resistance developed wherever DDT crop spraying was common. After the DDT bans went into effect in the United States and elsewhere, it continued to be used extensively for agriculture in Africa, and this exerted a powerful pressure on mosquitoes there to develop resistance. Although DDT is now prohibited for crop spraying in Africa, a few mosquito species there are still resistant to it.
“But DDT has other mechanisms of acting against mosquitoes beyond killing them. It also functions as a “spatial repellent,” keeping mosquitoes from entering areas where it has been sprayed, and as a “contact irritant,” making insects that come in contact with it so irritated they leave.
In Mosquitoes, DDT, and Human Health, he describes the death and suffering caused by insect-borne diseases, and tells why we must bring back DDT.
From the NYTimes:
Until a suitable alternative is found, DDT remains the cheapest and most effective long-term malaria fighter we have.
Discover has a short article, 20 Things You Didn’t Know About… Mosquitoes.
#3 In 1998, researchers found a new mosquito species in the London Underground, descended from ancestors that flew in when the tunnels were dug 100 years ago. Once bird-feeders, they now feast on a menu of rats, mice, and people. They rarely interbreed with their aboveground colleagues. Their DNA actually varies from one subway line to another.
#6 It would take 1,200,000 mosquitoes, each sucking once, to completely drain the average human of blood.