It was no walk in the park. But as Tony Kiszewski trekked across the muddy farms of Ethiopia last summer, the assistant professor of natural and applied sciences knew that each step brought him closer to slowing the spread of an often deadly disease: malaria.
Specifically, Kiszewski and other researchers are stalking a link between the mosquito-borne illness and maize, which is quickly becoming Africa’s leading food crop.
“We believe maize pollen provides an important source of nutriment for the larval stages of mosquitoes,” explains Kiszewski, who holds a PhD in tropical public health from Harvard University. Verifying the link could put the brakes on malaria’s debilitating spread, by informing strategies aimed at thwarting the growth of mosquitoes.
Caused by a parasite spread to humans through mosquito bites, malaria infects approximately 500 million people each year. It kills more than a million, most of them African children. Those stricken endure fevers, chills and nausea; coma and death are frequent outcomes. Prevention is key to combating the disease, since no vaccine exists and treatment medications are too expensive for most who are at risk.
Pollinating Pests
The forefront of disease prevention is familiar territory for Kiszewski.
As a master’s degree candidate at Cornell University during the early 1980s, he tackled the frightening phenomenon of river blindness. Parasitic worms are to blame for the illness, which afflicts millions of people on 11 continents. The Bentley professor participated in the first field trials for Ivermectin, helping to prove the now-common drug safe and effective against parasites that cause river blindness and a host of other diseases.
Malaria moved onto Kiszewski’s research agenda in 2005, when he met noted maize historian James McCann of Boston University. The two men and their Ethiopian colleagues compared maize cultivation data with malaria infection rates – and saw an intriguing pattern. As maize production increased, so did the local mosquito population.
According to field and laboratory data, mosquito larvae that ingest maize pollen mature faster, grow larger, and live longer than their non-maize-fed counterparts. Such observations are not just academic.
“By 2020, maize is expected to become the dominant food crop in Africa,” says Kiszewski. “Even now, malaria kills so many people in this area that foreign investors become diverted to healthier locations.”
Indeed, the United Nations has issued a compelling call to action. The agency’s Millennium Development Goals challenge world leaders to halt malaria’s spread, and reverse its incidence, by 2015.
Insects on a Diet
Funded by the Rockefeller Foundation, the project in Asendabo, Ethiopia, involves an international group of researchers. The U.S. contingent comprises Kiszewski, McCann, and members of the Malaria Initiative at the Harvard School of Public Health. In Ethiopia, research team members hail from the Infectious Disease unit of the Ministry of Health, the World Health Organization, science departments at Addis Ababa University and Jimma University, and the Ethiopia Agricultural Research Organization.
The team is working with 18 farms to deprive mosquito larvae of their presumed favorite food. For example, some farmers have moved hot pepper fields – a popular cash crop – closest to the mosquito breeding sites, shifting maize crops farther away. Others planted the prized teff grain nearest to where the bugs breed. Such plant redistributions could create a buffer around the maize fields, since maize pollen can’t travel very far.
The most recent trip included stops at each participating farm. Kiszweski and his colleagues set up traps to attract and collect mosquitoes; the nightly total was 500 per household. The researchers also recruited more study participants: residents of newly built homes, whose construction had created mosquito breeding sites in the pits that provided mud for plastering the walls.
With each visit, Kiszewski sees changes that make the landscape even more hospitable to mosquitoes. “We hope to discover and instill simple and sustainable modifications to agricultural practices that might halt or reverse these trends.”
Focused on that goal, Kiszewski is eager to return to Asendabo in summer 2009, as the next rainy season begins. “I expect that we’ll find fewer, smaller, and less long-lived mosquitoes as a result of these interventions, along with a correlating drop in malaria infections.”
And of course the professor has his rubber boots ready to go.