Mosquitoes gaining resistance to anti-malaria insecticides

According to a new study conducted in Senegal, the species of mosquito that commonly spreads malaria in Africa is developing increasing resistance to previously effective insecticides.
The study was published Thursday in the Lancet Infectious Diseases journal. The lead author was Jean-François Trape from the Institute of Development Research in Dakar, Senegal, Medscapre reports. Dr. Trape and his coworkers studied 504 inhabitants of Dielmo village, Senegal, between January 2007 and December. They found an increase of attacks by the Plasmodium falciparum species toward the end of the study, two years after insecticide-treated bednets were distributed.
"These findings are of great concern, since they support the idea that insecticide resistance might not permit a substantial decrease in malaria morbidity in many parts of Africa where A gambiae is the major vector and acquired clinical immunity is a key epidemiological factor," the authors wrote, according to Medscape.
The researchers found that 37 percent of collected A gambiae specimens were found to be resistant to the insecticide deltamethrin in 2010 and the mutation that results in insecticide resistant jumped from eight percent in 2007 to 48 percent in 2010.
"Our findings, in a closely observed population, show the high efficacy and substantial effect of combining effective vector control and effective case management, and support the reduction of the burden of malaria recently recorded in Senegal and elsewhere in Africa," the authors wrote, according to Medscape. "Unfortunately, our findings also show the threat posed by insecticide resistance to the sustained effect of this approach, and the speed at which changes can happen. Strategies to address the problem of insecticide resistance and to mitigate its effects must be urgently defined and implemented."
Accompanying commentary in the journal urges caution before generalizing the study's results with other countries in Africa. Joseph Keating and Thomas Eisele, both of the Department of Global Health Systems and Development at Tulane University, said that the study was conducted over a relatively short period of time for major conclusions about acquired immunity to be reached.
"Future studies should build upon these findings and account for secular, long-term trends in malaria transmission and other confounding factors," Keating and Eisele wrote, according to MedScape.