Wellness & Fitness

New insecticide seen crippling mosquitoes in malaria control war


Malaria remains a major global health concern due to its adverse impacts on people's lives and economies of affected countries.

Statistics from the World Health Organisation (WHO) indicate that the disease is responsible for about 627,000 deaths each year, with sub-Saharan African countries like Kenya accounting for 96 percent of those deaths.

A past study published in the Malaria Journal showed that the disease costs Kenya about $109 million (Sh10.9 billion) annually. This amount shoots to $250 million (Sh 25 billion) when costs associated with productivity losses are captured.

To reduce the burden of malaria, Kenya’s Health Ministry has been rolling out interventions, including the use of long-lasting insecticide-treated bed nets that are recommended by the WHO.

In as much as the nets have been instrumental, their effectiveness has been waning as mosquitoes have become resistant to the insecticide (pyrethroids) used to treat the nets.

This challenge has greatly contributed to the rising cases of malaria infections globally.

Those worst hits are children below five years and pregnant women who are the most vulnerable to the adverse health effects of the disease.

To tackle this challenge, public health researchers globally have been burning the midnight oil for alternative insecticides that can revamp malaria prevention through the use of bed nets.

After many years, their efforts are now beginning to bear fruits.

A new study published in the Lancet Journal says the use of bed nets treated with pyrethroids in combination with a novel insecticide known as chlorfenapyr, is effective in malaria prevention.

Unlike other insecticides which kill mosquitoes via the nervous system, the new one (chlorfenapyr) does so by curtailing movement.

It causes wing muscle cramps that lowers functioning. This prevents mosquitoes from making further host contacts or biting, ultimately leading to their death.

They, therefore, die from starvation or being unable to fend for themselves.

The study was conducted by the London School of Hygiene and Tropical Medicine (LSHTM), Tanzania National Institute for Medical Research, Kilimanjaro Christian Medical University College in Tanzania, and the University of Ottawa, Canada.

It involved more than 39,000 households and more than 4,500 children aged six months to 14 years from 72 villages in Misungwi, Tanzania, where high levels of resistance to pyrethroids have been reported.

Based on the research, the new nets reduce the prevalence or likelihood of malaria infection by 43 percent and 37 percent in the first and second year respectively, compared to the standard nets treated with only pyrethroid insecticides.

Specifically, the nets reduced clinical episodes of malaria by 44 percent. This refers to patients that test positive for malaria parasites through a blood test, while also having symptoms of the disease.

According to the researchers, the novel net could lead to significant malaria control gains in sub-Saharan Africa.

“Malaria remains a huge problem across sub-Saharan Africa and is one of the leading causes of death. We urgently need new interventions to get control efforts back on track,” stated Jacklin Mosha, the lead author of the study from the National Institute for Medical Research in Tanzania.

“By essentially grounding the mosquito, our work on adding chlorfenapyr to standard pyrethroid bed nets has great potential to maintain control of malaria transmitted by resistant mosquitoes in Africa,” said Manisha Kulkarni, a scientist at the University of Ottawa’s Faculty of Medicine.

According to Natacha Protopopoff, the Principal Investigator of the study from the LSHTM, the results of the research has shown that chlorfenapyr-treated bed nets are safe, cost-effective and can decrease malaria infection in children.

“At night, when the malaria mosquitoes naturally fly up against the treated bed nets, they get a severe case of muscle cramps so they buckle and fall to where they are likely to be carried off by scavenging ants... because of the unique mode of action, chlorfenapyr treated nets kill all kinds of mosquitoes that have evolved resistance to other insecticides. It should therefore have a long future.”

The scientists, however, note that more research is needed to examine the feasibility of scaling up the use of these nets in many countries.

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