Laced With 2 Insecticides, New Nets Protect Children From Malaria

Mosquito nets infused with two pesticides work much better against malaria than those with only one, reducing prevalence in children by 44 percent, according to a recent study.

As a result of the report, published in The Lancet last month, the World Health Organization has recommended that the two-chemical nets be used in areas where mosquitoes have developed resistance to the first-line insecticide.

The new nets contain pyrethroids, a class of chemicals used in nets for over a decade, along with the newer compound, piperonyl butoxide, which blocks mosquitoes’ ability to break down pyrethroids. (It is sometimes called a “pesticide synergist.”)

The Vestergaard company, which introduced pyrethroid-infused nets in 2004, later developed a two-chemical version that the WHO began evaluating in 2014. Now many companies have similar nets awaiting WHO approval.

It is hard to find new insecticides suitable for nets, because they must kill or repel mosquitoes and yet be safe for the babies and youngsters who sleep under them. The insecticides also must be able to stand up to washing and intense sunlight.

Piperonyl butoxide largely fades away after two years. In the study’s second year, protection by nets with piperonyl butoxide had diminished, and malaria prevalence in children was reduced by only 33 percent.

Insecticide-impregnated nets are considered an important factor in the world’s recent success against the disease: Malaria deaths dropped 60 percent between 2000 and 2015.

Other factors included coating walls inside homes with long-lasting pesticides, prophylactic treatment of pregnant women and young children during malaria seasons, new rapid malaria tests and treatment using compounds based on artemisinin, which comes from wormwood plants.