Long-lasting, insecticide-treated bed nets may not be as effective in the fight against malaria as previously believed, reports a study published in the Lancet. In fact, the use of the bed nets may actually aid a resurgence of the disease.
The study, which observed residents of Dielmo, Senegal shows that the Anopheles gambiae mosquito, which is responsible for about half of the malaria cases in Africa, may be developing resistance to the insecticide on the treated bed nets which have become a norm in preventing malaria. However, this isn't where the bad news ends. While the malaria population is in decline, people may lose their immunity to the parasite, making them more susceptible to contracting the disease when the mosquito population recovers.
Doctors from the Institute for Development Research in Dakar distributed bed nets in Dielmo in August 2008 after studying the mosquito population for a year and a half. For the first two years, malaria cases quickly declined — from August 2008 to August 2010, incidence of malaria decreased to less than eight percent in the village. However, between September and December 2010, the numbers increased again and malaria incidence rose to 84 percent.
However, critics of the study have cautioned against any drastic conclusions. Joseph Keating and Thomas Eisele, from the Tulane University School of Public Health and Tropical Medicine wrote in a commentary that while the study was thorough, the duration was too short and it only focused on one village in rural Senegal. This, they claimed, was not enough to state that the bed net program is ineffective.
Other critics of the study agreed, arguing that occurrence of malaria varied from year to year.
The news comes as the U.S. Agency for International Development (USAID), announced expansion of its Indoor Residual Spraying (IRS) program, a strategy that involves spraying safe insecticides to indoor walls and ceilings of homes, hoping to disrupt malaria by killing mosquitoes carrying the parasite. The three-year contract for $189 million will be implemented along with the Centers for Disease Control and Prevention (CDC).