A novel mosquito net that contains insecticides could prevent millions of cases of malaria, according to a Lancet study. A two-year clinical trial in West Africa involving 2000 children showed that the number of cases of clinical malaria was reduced by 12% with the new type of mosquito net compared to the conventional one used normally. Scientists including those from Durham University and Liverpool School of Tropical Medicine in the UK found that sleeping under the new bed nets were 52% less likely to be moderately anemic than those with a conventional net. Malaria anemia is a major cause of mortality in children under the age of two. The nets used in the study contain a pyrethroid insecticide which repels and kills the mosquitoes as well as an insect growth regulator, pyriproxyfen, which shortens the lives of mosquitoes and reduces their ability to reproduce. In areas with the new combination bed nets, there was a 51% reduction in the risk of a malaria-infective mosquito bite compared to areas with conventional nets.
This study is important because malaria control in sub-Saharan Africa has stalled, partly because the mosquitoes are adapting and becoming resistant to the pyrethroid insecticides used for treating the old bed nets. A trial carried out in Burkina Faso where the new types of the net, that had a pyrethroid plus an insect growth hormone, was used and it showed significant protection than the old net type.
The researchers said that if they had scaled-up their trial to the whole of Burkina Faso, they would have reduced the number of malaria cases by 1.2 million. Female Anopheles mosquitoes are increasingly becoming resistant to the most common insecticides, called pyrethroids, used to treat traditional bed nets.
Latest figures from the World Health Organization (WHO) show that after a dramatic decrease in malaria since the start of the millennium, progress has stalled, and the number of people infected with malaria is now going up in some areas, with insecticide-resistant vectors as one of the possible causes of this.
The researchers suggest the use of bed nets with a combination of chemicals, to be explored for areas where mosquito resistance is a problem. The ingredients on the nets kill more mosquitoes and reduce the number of infective bites than conventional nets treated only with a pyrethroid. As it is less likely that mosquitoes become resistant to both chemicals in the combination bed nets, they are considered a better alternative to tackling malaria in areas where mosquitoes have become resistant to the single chemical used in traditional bed nets. The latest figures from WHO show that in 2016 malaria infected about 216 million people across 91 countries, up to five million from the previous year. The disease killed 445,000 which was about the same number as in 2015. Most deaths were in children under the age of five in the poorest parts of sub-Saharan Africa.