Victory over the malaria mosquito: double-impregnated mosquito net prevents thousands of deaths

In recent years, the malaria mosquito has shown itself to be increasingly resistant to the older variants of mosquito nets. In March 2023, the World Health Organization (WHO) already issued an official recommendation of the double-impregnated nets. Eventually, all existing mosquito nets will have to be replaced.

What is new about the mosquito nets is that in addition to the usual poison, pyrethroid, a second agent has been added. Pyrethroid kills insects by shutting down their nervous systems. The second drug, chlorfenapyr, blocks the energy supply in insect body cells. Due to the combination of the two different mechanisms of action, pyrethroid-resistant mosquitoes are also not resistant to the new nets.

The Global Fund, a global organization for combating epidemics such as malaria, financed the project with the double-impregnated nets. They were tested in Tanzania and Benin. Another twelve other African countries joined the project. The number of malaria infections in those countries decreased by 20 to 50 percent, counts show.

Victory

Imperial College London calculated the number of thwarted infections since the new nets were distributed based on a long-running database of malaria infections and deaths.

Marijke Wijnroks, tropical doctor and affiliated with the Global Fund, sees the speed with which the project was rolled out as a victory. ‘With previous innovations, it often took five years before a new drug was widely distributed. At the moment, 60 percent of the mosquito nets are already of the new generation, one year after the WHO advice.’

According to the WHO, there were 249 million malaria infections in 2022, of which 608 thousand were fatal. Young children are particularly at risk from infection: 80 percent of deaths involve children under the age of 5, the WHO reports. The vast majority of infections occur in Africa.

Additional resources

The first large-scale vaccination campaign against malaria therefore started in July 2023. By 2025, 18 million doses must have been administered in twelve African countries. Young children need at least three doses of the vaccine, adults four.

After four vaccinations, the chance of becoming seriously ill is 40 percent smaller. The fact that the vaccine does not guarantee complete protection makes additional resources such as mosquito nets necessary.

Mosquito expert and entomologist Bart Knols, who was not involved in the project, also thinks that the speed of the rollout of antimalarials is important. ‘It is expected that a new insecticide will work against resistant mosquitoes. The only question is for how long.’ Knols expects that the malaria mosquito will eventually also develop resistance to the new insecticides, a fact that makes combating malaria a race against time.

Wijnroks acknowledges this. ‘Malaria is a perfect storm. Due to global warming, mosquitoes are increasingly able to survive, and political conflicts in African areas make effective control difficult, including with vaccinations. That is why it is important that we continue to invest in new resources so that we can act quickly.’

Funding for the current project also came from the Netherlands. In 2022, the state donated 180 million euros from the development cooperation budget.