Featured Research

from universities, journals, and other organizations

Mosquito nets do not work everytime, researchers find

Date:
January 10, 2011
Source:
Institute of Tropical Medicine Antwerp
Summary:
Long-lasting insecticidal nets have yielded an important breakthrough in malaria prevention, but this does not automatically mean they always work against diseases transmitted by insect bites. Against the transmission of kala-azar disease in India and Nepal, they did not have an effect, researchers have found.

Long-lasting insecticidal nets have yielded an important breakthrough in malaria prevention, but this does not automatically mean they always work against diseases transmitted by insect bites. Against the transmission of kala-azar disease in India and Nepal, they did not have an effect. This was reported by an international group of researchers, led by Marleen Boelaert of the Institute of Tropical Medicine Antwerp, in the British Medical Journal.

Related Articles


Kala-azar, or visceral leishmaniasis in doctor's speak, affects half a million people annually. The Leshmania parasite, in fact a group of related parasites, is transmitted by sand flies. The parasite destroys your blood cells, leading to an enlarged spleen, inflammation and progressive wasting. If left untreated, the outcome is fatal.

Until now, in India and Nepal sand flies are controlled by indoor spraying of DDT or other insecticides; some families use classical mosquito nets, which are not treated with long-lasting insecticides. Spraying happens local and irregular, which means at any moment sufficient sand flies and prey remain to continue the disease. As an alternative for DDT, a large scale campaign was proposed, providing everyone in a region with a mosquito net treated with insecticide that remains active for several years.

Such a campaign needs a large amount of money and effort, so the researchers of the Institute of Tropical medicine, together with colleagues from England, Switzerland, India and Nepal, first checked if it made sense. The prospects were good: in Sudan the approach had worked -- but there the disease was transmitted by a different sand fly. And in Syria and Iran, the treated nets had helped against cutaneous leishmaniasis, caused by other species of the genus Leishmania. It was also known that the sand fly transmitting the disease on the Indian continent, often bites indoor and mostly at night. So sleaping under a net had to make sense.

However. The scientists followed twenty thousand people during two years, in 26 hamlets with a high incidence of visceral leishmaniasis, in India and Nepal. The hamlets were divided into pairs, which resembled each other as much as possible. Tossing a coin decided which hamlet continued as usual, and which would receive treated nets on top. All communities had agreed with this procedure beforehand. During the period of the study, about half the villages were sprayed under the routine national control program.

In the hamlets with extra mosquito nets the sand flies indoor were reduced by a quarter, but the number of infections was not significantly lower than in the control hamlets. Neither did the number of cases of leishmaniasis (luckily, not every infection leads to disease). To be precise: the disease risk went down with 1%, which could be just as well due to chance. Yet in the campaign-villages 90% of people slept under their nets for more than 80% of the nights, while in the control hamlets only 30% of people slept regularly under an (untreated) net.

In contrast, the number of malaria cases did significantly go down in the villages with the extra nets.

The most likely explanation is that sand flies bite more often outdoors than was previously assumed, where nets are not readily useable.

This study, the first on such a scale, shows that medicine shouldn't generalise its results too fast, and that it's always a good idea to do field research before launching grand scale campaigns. And that, for such a campaign against kala-azar to have effect, research into the behaviour of sand flies is urgently needed.


Story Source:

The above story is based on materials provided by Institute of Tropical Medicine Antwerp. Note: Materials may be edited for content and length.


Journal Reference:

  1. A. Picado, S. P. Singh, S. Rijal, S. Sundar, B. Ostyn, F. Chappuis, S. Uranw, K. Gidwani, B. Khanal, M. Rai, I. S. Paudel, M. L. Das, R. Kumar, P. Srivastava, J. C. Dujardin, V. Vanlerberghe, E. W. Andersen, C. R. Davies, M. Boelaert. Longlasting insecticidal nets for prevention of Leishmania donovani infection in India and Nepal: paired cluster randomised trial. BMJ, 2010; 341 (dec29 1): c6760 DOI: 10.1136/bmj.c6760

Cite This Page:

Institute of Tropical Medicine Antwerp. "Mosquito nets do not work everytime, researchers find." ScienceDaily. ScienceDaily, 10 January 2011. <www.sciencedaily.com/releases/2011/01/110105071141.htm>.
Institute of Tropical Medicine Antwerp. (2011, January 10). Mosquito nets do not work everytime, researchers find. ScienceDaily. Retrieved April 25, 2015 from www.sciencedaily.com/releases/2011/01/110105071141.htm
Institute of Tropical Medicine Antwerp. "Mosquito nets do not work everytime, researchers find." ScienceDaily. www.sciencedaily.com/releases/2011/01/110105071141.htm (accessed April 25, 2015).

Share This


More From ScienceDaily



More Plants & Animals News

Saturday, April 25, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Dispute Flares Over Controversial Thai Temple Tigers

Dispute Flares Over Controversial Thai Temple Tigers

AFP (Apr. 24, 2015) Thai wildlife officials begin a headcount of nearly 150 tigers kept by monks at a temple which has become the centre of a dispute over the welfare of the animals. Video provided by AFP
Powered by NewsLook.com
College Kegger: University Gets in on Craft Brew

College Kegger: University Gets in on Craft Brew

AP (Apr. 24, 2015) Theres never been a shortage of beer on college campuses. But students at Cal Poly-Pomona are learning how to brew, serving their product to classmates, and hoping to land jobs in craft breweries when they graduate. (April 24) Video provided by AP
Powered by NewsLook.com
Cambodian Butterflies Help Villagers Make a Living

Cambodian Butterflies Help Villagers Make a Living

AFP (Apr. 24, 2015) Cambodia&apos;s Banteay Srey Butterfly Centre is the largest of its kind in Southeast Asia. As well as educating tourists about the creatures, it also offers a source of income to nearby villagers, who are paid to breed local species. Duration: 02:04 Video provided by AFP
Powered by NewsLook.com
3D Food Printing: The Meal of the Future?

3D Food Printing: The Meal of the Future?

AP (Apr. 23, 2015) Developers of 3D food printing hope the culinary technology will revolutionize the way we cook and eat. (April 23) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins