Mobile experimental malaria huts trialled in Tanzania
[MBEYA, TANZANIA] Improvements to the design of mobile huts designed to study malaria transmission in rural Tanzania have provided new insights into mosquito behaviour.
Experimental huts have been used in Africa since the 1940s, and improvements have been introduced over the years to enable researchers to better understand how mosquitoes behave in human dwellings.
A new hut design was developed by scientists at the Ifakara Health Institute, in Tanzania, in 2007.
The huts have been used in a range of malaria transmission studies in Benin, Kenya, Tanzania and Zambia in recent years. They come in a kit form, which means they can be moved from place to place, allowing for more efficient studies compared to permanently located experimental structures.
"You [can easily] dismantle the whole hut, take the panels to another place and plug it in, in a short period," said Nico Bovela, a senior research scientist at the institute.
"The major problem with [previous designs] is with experimental flexibility," he said.
"If you want to capture variations across different places it becomes difficult unless you build huts in [every area you wish to study], which is very expensive and no donor would be willing to support it."
The modified huts also include traps to help identify which mosquito species enter at different times of day and night, and removable ceiling and wall panels to test mosquito responses to different insecticides.
In this latest study the huts were trialled in a rice-producing village in south-eastern Tanzania to study the behaviours of local mosquito species, including peak feeding times, preferred entry and exit points to dwellings, and their reaction to malaria-prevention strategies such as insecticide-treated walls and bed nets.
The study, published in PloS One last month (9 February), suggested the extension of existing interventions, including outdoor spraying of insecticide, rather than indoor spraying alone, as had been the case in the past.
It also provided evidence for making improvements to village huts, including blocking gaps in eaves to discourage mosquitoes from entering.
The study also tested the effectiveness of the hut design, and made a range of recommendations for future studies, including the need to alter the use of entry and exit traps.
Overall, the researchers said the huts replicated conditions in ordinary village dwellings well, but stopped short of advocating them as a replacement for other experimental hut designs. Rather, they suggest that malaria researchers identify the specific behaviour they wish to study, in order to determine whether Ifakara's mobile huts would meet their experimental needs.
Donan Mbando of the Ministry of Health and Social Welfare, in Tanzania, said the study would be relevant to policymakers in the design of better prevention measures, and in making recommendations on drug therapies.
"It is better to use local facilities and measures," he told SciDev.Net.