[KATHMANDU] Insecticide-treated bednets that kill sand flies, responsible for the spread of leishmaniasis, may help prevent a disease that kills thousands of people every year in tropical countries, a new study shows.
The study in India and Nepal shows that use of long-lasting insecticidal nets reduces sand fly density by 25 per cent, and could supplement prevention strategies.
The study is part of KALANET, a European Commission project to measure the efficacy, acceptability and cost-effectiveness of bednets to prevent visceral leishmaniasis, a serious and often fatal form of the infection that affects the liver and spleen. It was conducted in 12 endemic villages of India's Muzaffarabad district and the Sunsari district of Nepal between 2006 and 2007.
Leishmaniasis is the second largest parasitic killer in the world after malaria. It infects half a million people every year and is responsible for 60,000 deaths worldwide. The Indian subcontinent alone accounts for 40,000 cases; and the governments of Nepal, Bangladesh and India together pledged in 2005 to eliminate the disease by 2015.
In the absence of a vaccine, governments rely on finding and treating infections; and prevention strategies such as spraying insecticides to decimate the vector. But success has been limited.
"While the efficacy of insecticide-treated nets for malaria control has been widely researched, this is the first trial to look at their use in the prevention of kala-azar," Suman Rijal, professor of tropical medicine and infectious diseases, at Nepal's B. P. Koirala Institute of Health Sciences, one of the study authors, told SciDev.Net.
The trial provides the first evidence that community-wide distribution of insecticide-treated bednets reduces the indoor sand fly density in endemic villages.
However, the 25 per cent reduction in sand fly density is much lower than the 59–80 per cent reduction in mosquito density observed in malaria control trials of similarly treated nets in Africa, the researchers observe.
Each net costs approximately US$5 and comes with a five-year guarantee.
The findings were published in PLoS Neglected Tropical Diseases last month (26 January).
PLoS Negl Trop Dis doi:10.1371/journal.pntd.0000587 (2010)