A new study from Senegal has experts worried about the spread of malaria through mosquitoes. The study has shown that mosquitoes can form a resistance to the insecticide used in mosquito nets.

Researchers studied the Senegalese village of Dielmo, over a span of years from 2007 to 2010. This documented the Malaria morbidity both before and after the 2008 distribution of long-lasting insecticide bed nets, a leading method in preventing malaria. Though some experts say the study was too small to draw conclusions, but the findings are troubling.

The study shows that mosquitoes may be forming a resistance to the insecticide. While just three weeks after the net introduction, there was a short-term decline in malaria attacks, the proportion of mosquitoes genetically resistant to a type of pesticide rose from 8 percent to 48 percent.

In 2010, the pesticide Deltamethrin, which is recommended by the World Health Organization for bed nets, was genetically resisted by 37 percent of Anopheles gambiae mosquitoes, the principal vectors for malaria in Africa.

This led to a raise in malaria attacks back to high levels, for the last few months of the 2010 study period. In fact, the rate of attacks was even higher amongst older children and adults than it was before the bed net introduction. According to the study, this is possibly related to a reduced immunity among these age groups.

According to the Center for Disease Control, in 2008 there were an estimated 190 to 311 million cases of malaria worldwide, causing 708,000 to 1,003,000 deaths. Most of these deaths occurred in young children from sub-Saharan Africa.

“Strategies to address the problem of insecticide resistance and to mitigate its effects must be urgently defined and implemented,” said the researchers in study.

Image Courtesy of  http://www.flickr.com/photos/gatesfoundation/

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Lindsey Kratochwill