Low-technology approaches to mosquito control can be effective

Over 380 000 people have been protected from dengue fever in Vietnam thanks to the implementation of a novel strategy to control mosquitoes in the country, concludes a report in this week’s issue of The Lancet.

Dengue fever is the most common insect-borne virus infection, causing more than 50 million infections, 500000 cases of dengue haemorrhagic fever and at least 12000 deaths per year. The mosquito, Aedes aegypti, is the major global vector of dengue viruses. It needs stagnant water to breed and is commonly found in water storage containers.

Brian Kay (Royal Brisbane Hospital, Queensland, Australia) and Vu Sinh Nam (Ministry of Health, Vietnam) developed a mosquito control strategy and evaluated it in 12 provinces in Vietnam from 1998 to 2003. Their strategy involves inoculating large water storages with crustaceans called Mesocyclops, which feed on mosquito larvae and targeting containers that produce the most mosquito larvae. Community education and activities, such as the collection of discarded containers, also form an important part of the strategy.

The authors report that A aegypti has been eradicated in most villages in the programme and no cases of dengue fever have been reported in any of the villages since 2002. The findings suggest that this strategy is sustainable in Vietnam and applicable where the major sources of A aeygpti are large water storage containers.

Professor Brian Kay concludes: “Although the government of Vietnam has adopted this strategy into their national programme, the challenge is to transfer this framework to the rest of Southeast Asia and beyond. Whereas the hierarchical structure of society in Vietnam undoubtedly affected successful adoption of our model, we judge the key factor in motivating communities to be perception of the seriousness of the dengue problem. As the global prognosis is poor, we predict that this model, or modification of it, will become increasingly important.”

In an accompanying commentary Simon Hales (Wellington School of Medicine and Health Sciences, New Zealand) and Wilbert van Panhuis (Catholic University of Louvain, Belgium) write that it is not clear how successful this strategy might be in cities or in other countries.

Dr Hales states: “Kay and Nam show that low-technology approaches to vector control can be effective if well planned and supported, with strong emphasis on community participation. Their strategy is not a universal answer to the problem of dengue, but has the potential to make an important difference in rural communities.”