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Cause and Solution: A New Perspective on Malaria and Agriculture

Researchers collect mosquitoes to determine the source of blood "meals". (IDRC Photo: Peter Bennett)

2003-08-12

Village leader Justus Mwangi is not working in the rice fields today. Instead, in the midday heat, he stands in the shade of a tree discussing the community’s number one health problem — malaria. “You are disabled because you can’t walk,” he explains. “It brings headaches and fatigue.”

Among the 53 families living here in Mbui-Njeru, Kenya, someone is always suffering from the disease. Yet just behind Mwangi, quietly swatting flies with its tail, stands a possible weapon in the fight against malaria — a black and white cow. Research has shown that certain species of malaria-bearing mosquitoes prefer the blood of cattle to that of humans. As part of a larger investigation into malaria at the Mwea Rice Irrigation Scheme, researchers with the International Centre for Insect Physiology and Ecology (ICIPE) and the International Water Management Institute (IWMI) are exploring whether cattle could be used as “bait” to divert mosquitoes away from humans.

Another potential strategy is to reduce mosquito-breeding habitats by limiting the amount of water used for rice cultivation in the Scheme.

The project, using the International Development Research Centre’s (IDRC) ecohealth approach is thus improving human health, focusing not on health care interventions but on better management of the agricultural ecosystem.

“The link between irrigated tropical agriculture and malaria is pretty convincing, so it makes sense to try to attack the problem at the source,” says Clifford Mutero, the entomologist heading the research team.

Labour camp origins

Efforts to grow irrigated rice in Mwea began under British colonial rule. But it was not until the area was turned into an internment camp for captured Mau Mau fighters rebelling against colonial rule in the 1950s that rice could be cultivated on a wide scale. The detainees were forced to dig canals, build dams, and work in the paddies. With independence in 1963, the new government took over the Scheme and settled landless peasants there to work and live alongside the ex-freedom fighters. Today more than 3,000 families live in tightly-packed villages within the Scheme, which covers 13,640 hectares and produces 80% of the rice consumed in Kenya. They do not have land tenure and live in poverty.

About half the Scheme’s hectares are devoted to rice, irrigated by water from the slopes of Mount Kenya. The paddies are submerged for half the year, providing an ideal habitat for mosquitoes. In some areas, farmers cultivate rice “informally” year-round. If more land is diverted from cattle grazing to rice and the cattle population drops, malaria could increase.

Approximately 20% of community members have malaria parasites in their blood at any one time. As elsewhere in Kenya, where 75 to 100 children die every day from malaria, conventional efforts to control the disease have not worked. Increasingly, malaria parasites are resistant to drugs, and the mosquito vectors to the insecticides. These control methods are also expensive for the farmers, who are lucky if they earn US$500 a year.

Searching for new lines of attack, Mutero’s team is focusing on the immediate problem — a mosquito infecting a person with malaria — and then taking a “wide-angle” view that takes in poverty in the villages, farming practices in the rice fields, and men sitting idle while their wives work. This helps determine the reasons behind the malaria statistics.

Community involvement

At the heart of the ecosystem approach is community participation. In Mwea, villagers are involved in all phases of the project. An initial workshop brought together participants from 17 organizations, including government, the rice growers’ association, and church and community groups.

The next step was to compile an information “inventory” of four villages. The project trained 10 local people to work as research assistants and the team gathered such basic information as age, sex, education, income, occupation, family size, nutritional status, religious and cultural affiliations. They also learned about broader issues, such as health problems, poverty, social ills, and conflict in the Scheme. Throughout the research, consideration was given to the different roles and responsibilities of women and men. They were often interviewed separately so they could freely air their views.

The researchers then assessed the crop and livestock production systems and how these relate to people’s health. They experimented with ways to reduce the mosquitoes’ wet habitat by introducing a crop that grows in dry conditions and by cultivating rice with less water. More traditional research included collecting mosquitoes in households in the early morning to determine the source of their blood meal — human or livestock. To assess malaria prevalence, researchers also analyzed blood samples from children.

Possible solutions

Another characteristic of the ecohealth approach is transdisciplinary research. The project team includes a medical entomologist, a medical parasitologist, a public health expert, a crop/livestock expert, a veterinarian, an anthropologist, a sociologist, and a statistician. Three team members are women.

Such transdisciplinary research usually means moving outside the confines of one’s particular discipline. “If you are the best in your field, it’s not good enough,” says Jean-Michel Labatut, a senior program specialist with IDRC’s Ecosystem Approaches to Human Health (Ecohealth) program initiative. “You have to have an open mind.”

Accordingly, the team came up with an integrated series of solutions to the malaria problem in Mwea:

• Improved water management: reducing the amount of time that paddies are wet, either by changing flooding schedules or alternating rice cultivation with a dry-land crop such as soya. In addition to limiting the mosquitoes’ habitat, planting soya could boost income and improve nutrition. Mwea children often suffer from protein deficiencies, says Mutero, because “it’s rice for breakfast, rice for lunch, and rice for dinner.”


• Livestock as bait: using cattle to divert blood-seeking mosquitoes away from humans and promoting cattle-raising by using rice husks, which are ordinarily burned as waste, as animal feed. Preliminary research found that the village with the highest number of mosquitoes per household had the lowest prevalence of malaria — because it had the highest livestock population.


• Biological control: introducing naturally occurring bacteria into stagnant water to kill mosquito larvae during the peak breeding season. Such biological control agents would be harmless to humans and other animals.


• Mosquito nets: providing insecticide-treated bednets for high-risk groups — young children and pregnant women — through partnerships with non-governmental organizations (NGOs). Nets are expensive for farming households but NGOs could help offset the costs.

Researchers are now looking ahead to a possible second phase when interventions could be introduced. The lessons learned are also being carried forward by the Systemwide Initiative on Malaria and Agriculture (SIMA), a new consortium coordinated by Mutero and based at the IWMI Regional Office for Africa. SIMA’s goal is to show, through research and capacity building, that communities can adopt agricultural practices to reduce and prevent malaria. The ecohealth approach is central to much of SIMA’s work.

“When you get to my stage in life, you want to do something that is of practical relevance,” says Mutero. “It makes sense to embrace this holistic approach to solve problems.”

Jennifer Pepall is a writer in IDRC’s Communications Division.

For more information:

Ecosystem Approaches to Human Health Program Initiative, IDRC, PO Box 8500, Ottawa, Ontario, Canada K1G 3H9; Phone: (613) 236-6163; Fax: (613) 567-7748; Email: ecohealth@idrc.ca; Web site: www.idrc.ca/ecohealth

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