Protozoa, Worms and Flukes, Oh My

Protozoa, Worms and Flukes, Oh My! Professor Andrew David’s students agree: his enthusiasm for parasites is infectious. by Kristen Schmitt

It was love at first parasite for Professor Andrew David, who discovered his penchant for invasives when he was an undergraduate dissecting clams brimming with unwanted guests on a clam farm in Greenwich, Connecticut.

“It looked really gross to most people, but to me, they were really cool,” says David, who shares his passion for marine biology and parasitology as an assistant professor in the biology department at Clarkson. “Marine biology allows me to do a bit of everything — genetic work, ecological work, biochemistry — it’s a very broad field.”

David’s passion for parasites is infectious; his parasitology course was recently highlighted in the professional journal Trends in Parasitology as a gold standard for teaching the topic. Although the course has traditional lectures, David engages his students with projects centered on tackling realworld problems that seriously affect human health, including malaria, toxoplasmosis and trypanosomiasis, which causes sleeping sickness in tropical countries.

While David’s research has taken him as far away as the tip of South Africa to study farmed shellfish, his latest research is focused on the rivers and lakes of the Adirondack region. Last year, David, along with students Susan Verra ’17, Hanson Zhou ’18, Ashley Lewis ’17 and Arianna Yhann ’18, discovered a parasite that had never been recorded in the region. The parasite is a trematode worm that spends part of its life inhabiting the tissues of the banded mystery snail (Viviparus georgianus), a mollusk invasive to Northern New York that David and his team are currently investigating. While they think that the trematode may be using Canada geese to complete its development to an adult, the life cycle of this parasitic species is still being studied.

“We think it’s being transmitted by Canada geese migrating from Canada to the waterways of the Adirondacks,” says David. “This species partially develops in snails, and the geese feed on the snails, completing its life cycle. Whether it’s a new species is something we’re still trying to figure out.”

Some students assisted David with the initial research, working to identify the host snail species using DNA barcoding. Others recorded the measurements of the snails collected, wrote scientific descriptions of the species and statistically analyzed the data collected. While the snails may be invasive, David isn’t sure yet if they actually harm humans or if they’re just a nuisance.

Prof. Andrew David

“All of these students took either my zoology or parasitology course,” says David. “So they were able to put what they learned in the classroom into actual practice.”

Classroom learning and field investigations led students to the discovery of a new parasite in the Adirondacks.