Mosquito nets not effective: Study

Health Watch

THE once effective insecticide-treated mosquito nets are not providing the protection they once did.
A research conducted on the increase of malaria cases have shown that the nets are not effective.
The long-lasting insecticidal nets (LLINs) have been the backbone of the global battle against malaria, credited with having saved 6.8 million lives from 2000 to 2015.
However, scientists said the change in the efficiency of the nets was a serious concern for tropical and subtropical countries.
The insecticide on the nets added community-level protection by decreasing the number of mosquitoes, this means that even people in the community who are not using the nets benefit from it.
“While an untreated net stopped mosquitoes from biting you while you sleep – providing valuable protection – these nets are treated with a long-life insecticide that kills mosquitoes that come in contact with them,” said Dr Stefan Karl, a malaria researcher from James Cook University and PNG Institute of Medical Research.
When the LLINs were introduced to PNG in 2006, there was a significant drop in malaria cases but the rate of infections have bounced back from less than one per cent in 2013-2014 to 7.1 per cent in 2016-2017.
The researchers believed the increased rate of cases was because of a shortage in anti-malarial drugs but after drug supplies were restored, cases continued to climb.
Further studies ruled out other possibilities as to why cases were still increasing.
It was only after they tested the nets performance at knocking down and killing mosquitoes when the problem was revealed.
“With new nets manufactured up to 2012, the percentage of mosquitoes killed was always close to 100 per cent,” Dr Karl said.
“Using the same standard tests with new nets produced from 2013 to 2019, the kill rate dropped to an average of 40 per cent, with some of the nets not killing any mosquitoes at all.”
The discovery is an alarming loss of efficiency in critical protective equipment.
All the nets tested appeared to have the same amount of insecticide, so this brings up the question of how nets with the same insecticide levels could be less lethal to mosquitoes.
The researchers said the most likely answer lies in changes on the manufacturing of the nets.
“We hope to work with the manufacturer to investigate further,” Dr Karl said.
Meanwhile, the researchers have notified the WHO and the manufacturer of their findings and urged that all LLINs be tested.

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