Collaboration: The missing link in malaria transmission

Kenyan researcher looks at which man-made and natural factors influence how the Malaria spreads.

Gabriel O Dida’s only sister died from malaria when he was a teenager growing up at the banks of Lake Victoria in Kenya. That was in 1999, the parasite had already been studied for over a century, and still there seemed to be no solution in sight. What was taking so long, Dida asked himself, to eradicate the disease?

Gabriel O Dida in the field.

As a graduate student in biology he later found there were many reasons. One of them he could help tackle: “I realized that the simplest ecological link between mosquito and malaria transmission was given little attention.” So Dida began to conduct his own research at the University of Maseno in Kisumu in Western Kenya to find which man-made and natural factors influence how the disease spreads.

For example, Dida and his colleagues studied whether cows can divert mosquitoes’ appetite, and lure them away from humans. The researchers also inspected the influence of insecticide-treated bed nets in this interaction. What they found was a push-pull effect: cows attract certain types of mosquitoes, while bed nets repel and kill them. Both factors taken together have the potential to decrease malaria transmission rates.

Now Dida is out to nip the problem in the bud. He’s inspecting breeding grounds along the shore of Lake Victoria, which is known as the world’s deadliest malaria zone. According to a report by the World Health Organization from 2013, more than 7.5 percent of the population there is infected. Its shallow, warm waters are the preferred breeding ground for the Anopheles mosquito, the parasite’s vector. The mosquitoes from breeding grounds in two villages in the Mbita district caught Dida’s attention. In the area, malaria accounts for 35 percent of all child deaths.

Dida believes that there’s a direct link between ecological factors at these breeding grounds and high malaria transmission rates. Searching for the best way to prove his hypothesis, he asked peers on ResearchGate for help. Here he heard from Frank Baily Gelder, a pathologist from New Zealand. Together Dida and Gelder browsed the literature and went through possible protocols.

<em>Possible mosquito hatching sites.</em>
Possible mosquito hatching sites.

“The conversation with Frank Gelder made it much easier for me to implement a pilot,” Dida says.  As a first step he is now mapping his sampling sites. Later he will look for distinct features that could influence breeding conditions at those sites, like vegetation, agricultural use or construction work. Dida will then collect mosquito samples in nearby houses and analyze the mosquitoes’ stomach content. This, Dida assumes, will provide the missing link he’s looking for.

The DNA analysis of the mosquitoes’ stomach content will tell Dida what they were feeding on. He’ll learn whether mosquito populations from certain breeding grounds really draw more human blood and infect more people than those from others. Finally, he’ll compare the ecological factors at each habitat. This will hopefully reveal what’s turning some breeding grounds into deadly malaria hotbeds. Dida says: "I know that this solution will not only be of global public health importance, but also have direct health benefits to those living in rural Kenya, where I grew up."

Update December 2015: You can now read the paper Dida and Gelder paper wrote together on ResearchGate.

Presence and distribution of mosquito larvae predators and factors influencing their abundance along the Mara River, Kenya and Tanzania

All photos courtesy of Gabriel O Dida.