Targeting mosquito larvae and not adults could worsen dengue epidemics, study says

Targeting only mosquito larvae and not adult insects in insecticide-based dengue control programs could increase mosquito resistance and decrease human immunity to the disease, particularly in urban areas, according to a study published online in the Lancet on Tuesday, Agence France-Presse reports.

Approximately 2.5 billion people are at risk of dengue worldwide, and incidence has risen dramatically over the past few decades because of increased urbanization and rising temperatures attributed to global warming, the news service writes. There is no cure, treatment or vaccine for the disease, and the only way to fight it is to eliminate the mosquitoes that carry it, especially the Aedes aegypti (Hood, 5/2).

Using mathematical and computer modeling of dengue transmission, researchers examined the cost effectiveness of 43 different insecticide-based interventions and found that all the methods caused insecticide resistance, which when coupled with a loss of human immunity, "will increase the magnitude of future dengue epidemics," the researchers wrote (Luz et al., 5/3). The vector control method "prevailing in most countries - attempting to destroy breeding areas - is misguided, according to the study," AFP reports.

"The main conclusion is that when you compare all the proposals for controlling dengue, the most cost effective is killing adult mosquitoes," Eduardo Massad, a professor at the School of Medicine at the University of Sao Paulo who was not involved in the study, said, according to AFP. He added, "The most applied strategy is to search and destroy breeding places. This has not worked well - we need a new strategy, one that doesn't exist yet" (5/2).