Read our OA manuscript in Molecular Ecology Resources

Parasites are tricky animals in their own right. We forget that sometimes– thinking of parasites as a symptom or a consequence of something rather than as their own entity. Macroparasites, the tapeworms and cestodes and flukes of the world– they are animals. And they have wild ways of living their lives.

During my postdoctoral work, I fell headfirst into the world of parasites. The parasites we have been working on are a fascinating tapeworm called Schistocephalus solidus which must be consumed by three different animals in order to reach adulthood. Isn’t that insane? They begin in the wilds of lake sediment as eggs. They must be consumed by a zooplankton (copepod), which then must be consumed by a fish. That fish is eaten by a bird. Only then—inside a warm-blooded avian gut—can the parasite finally reach sexual maturity and reproduce. It’s less “circle of life” and more “gauntlet of digestion”.

Everyone knows tapeworms. Tapeworms have wrecked havoc on the world. They affect our dogs and cats, our cattle and sheep, and can be absolutely debilitating for humans. The thing is. . . we know a lot about tapeworms once they are big. But how tapeworms start their lives is kind of a mystery. How do they get from an egg floating in a lake to the body of that first host? This early chapter is surprisingly mysterious.

This paper is all about generating that first insight. What is the infection intensity in first-intermediate hosts in wild populations?

To answer that, we turned to a powerhouse molecular tool: droplet digital PCR (ddPCR). Imagine regular PCR, but supersized—replicated 20,000 times in parallel. It’s incredibly sensitive, able to detect the faintest traces of parasite DNA in a single, transparent zooplankton drifting through the water column. It’s a first and important step to systematically quantify infection dynamics in first-intermediate hosts. It took a lot of troubleshooting, a lot of learning, and more than a few “why won’t this work” moments. But in the end, we developed a set of primers and probes that can detect early-stage helminths, not just in S. solidus, but n a range of tapeworms and flukes.

If you’re interested in cryptic infections, trophic transmission, or just love a good parasitic mystery, this paper is for you. Take a peek and maybe you too can be a space-traveling Indiana Jones, following parasites through space and time. Oh my!

Stay tuned for really sexy papers about infection dynamics in first-intermediate hosts across time. I am cooking with gas now, friends.