Drone imagery helps predict schistosomiasis infection areas


I’m Chelsea Wood, I’m a parasite ecologist
and I study the ecology of the human disease schistosomiasis. So schisto is a trematode parasite, it’s a
flat worm and it lives inside the human circulatory system. And it needs two hosts in order to complete
its life cycle – people and snails. So it lives in the blood vessels of people. There, it produces eggs. Those eggs are passed out of the body in urine
or feces, and then they go into natural freshwater bodies like streams or rivers or lakes. The snails then incubate the parasite and
they just pump out millions of clones of this parasite and they penetrate the skin of people
who are bathing in those freshwater bodies. What you wind up seeing in patients who’ve
been infected for a long period of time with a large humber of worms is abdominal pain
and distention and ultimately bladder cancer or liver cancer – it’s awful. Our study was trying to identify ways to find
heavily infected villages that would be easier than going out and diagnosing people, because
it’s a difficult and time-consuming and labor intensive process. And one of our easier ways was to actually
count the snails that are present at a site. The more snails, the more potential schisto,
the more transmission risk. You’re working in super hot conditions. The water around you is infested with schistosome
cercaria and so the technicians who are doing that sampling can’t touch the water. We also flew drones over each of our villages
and estimated the amount of area covered by the habitat that the snails really love to
hang out in, which are these particular species of floating vegetation. And you’ll see that it’s a different color – dark green, sometimes brownish. And so what we actually found was that it was
way more accurate to use the drone images than it was to actually use counts of snails. These aerial images provided a much better
proxy for where humans were infected than the very labor and time intensive snail data
provided. And that’s a huge benefit, because it means
that rather than actually traveling out to those villages to test human urine, they can
do a quick drone fly over or download some satellite imagery and immediately see what
the transmission risk is for a variety of villages, even ones that are really remote. Our hope is that this work doesn’t stop with
schistosomiasis but that we can be part of the growing community of ecologists who are
working to contribute our knowledge to an understanding of how to better manage and
control neglected tropical diseases.

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