Mattress nets with insecticide minimize the unfold of mosquito-borne ailments regardless of resistant bugs


It sounds like a contradiction, but it’s true: mosquito nets treated with insecticides are effective against even some insecticide-resistant mosquitoes, a new study shows.

Why it matters:

Mosquito nets treated with insecticides are one of the most effective ways to prevent malaria. The nets work both by preventing people from being bitten and by killing mosquitoes that come into contact with the nets. However, the World Health Organization has only approved one class of insecticide for the nets called pyrethroids, and mosquitoes across Africa are developing resistance to this insecticide.

The essentials:

Researchers, led by Hilary Ranson of the Liverpool School of Tropical Medicine in the UK, exposed Anopheles gambiae mosquitoes to insecticidal nets or untreated nets in the laboratory and then studied how long they lived. In previous research, scientists had only looked at whether the mosquitoes survived for 24 hours after touching a net, calling those that survived “insecticide resistant”.

“Whether the mosquitoes live long enough to transmit disease is the really more interesting parameter,” said Ransom.

Surprisingly, in data released Monday in Proceedings of the National Academy of Sciences, they found that many of the mosquitoes exposed to insecticides died after the first 24 hours. Overall, the allegedly resistant mosquitoes lived about half as long as mosquitoes that were not exposed to the insecticide.

And that has a huge impact on the transmission of malaria. The researchers calculated that contact with a treated net reduced the likelihood of a resistant insect transmitting malaria by two-thirds.

You should know:

Resistant mosquitoes lived longer after contact with the treated net. “I think it still sets off a lot of alarm bells for what might happen in the future,” Ransom said if resistance continues to rise.

What you say:

“This particular study is very interesting and enticing, but we need a lot more studies like this one,” to really know for sure how insecticides affect malaria transmission, said Andrew Read, director of the Center for Infectious Disease Dynamics at Penn State University. He pointed out that research was limited to two strains of a single Anopheles mosquito; others of the genus also transmit malaria.

Ranson agreed and suggested that field studies on resistant mosquitoes would be an important next step.

The bottom line:

Treated bed nets still work despite the mosquito’s growing resistance, but monitoring resistant strains and developing new insecticides will be important in the future.

Reprinted with permission from STAT. This article originally appeared on July 11, 2016.

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