Passing Disease – Flies
Ambience: Dawn chorus, Botswana
It’s a major killer of children worldwide and controlling this disease is a complex challenge, especially in developing nations. I’m Jim Metzner and this is the Pulse of the Planet.
Alexander: So, I’d been working in Botswana for nearly two decades, and I started noticing that people had diarrhea, not all the time, but some particular times. When it rained, when it was the wet season, everyone started to get sick, and in the dry season people would get sick. Now, that was very surprising to me. I couldn’t come up with any answers as to why this would be the case.
Dr. Kathleen Alexander is an Associate Professor in the College of Natural Resources and Environment at Virginia Tech. She spends much of her time in Africa, studying diseases like diarrhea, which are passed between humans and animals. She’s unlocking some of the puzzles of how the disease is spread.
Alexander: And t this point in time I was sitting with one of the nurses, and I started telling her about our results. And I said, “Yeah. I just can’t figure this out. Why in the world would the dry season have 20 percent more diarrhea every year, on average, over the last 30 years?” And she thought about it, and she said, “Well, it’s the flies.” And then, I thought about this And, in fact, when I started looking, the environmental conditions that surround the peak of diarrheal disease in the country, when it’s driest and it’s hottest, are the same factors that increase fly density and activity.
Alexander: In absence of really good sanitation, flies can be a major problem and connect people and waste in the environment, either through their food or directly through their hands and face. They might move from your food to your latrine or your toilet area, so, if fly densities change at a certain time of the year, you can imagine, then, that that could just amplify up if you start adding that to an outbreak of diarrheal disease. And that’s what we think is happening.
Pulse of the Planet is made possible in part by the National Science Foundation. I’m Jim Metzner