"So, naturalists observe, a flea has smaller fleas that on him prey; and these have smaller still to bite ’em; and so proceed ad infinitum."
- Jonathan Swift

March 2, 2010

March 2 - Echinostoma trivolvis

Echinostoma trivolvis, as well as other species of echinostome trematodes, are best known from their ubiquitous distributions and high abundance. The basic life cycle of E. trivolvis involves ramshorn snails (Planorbidae) as first intermediate hosts, a variety of snails, amphibians, fish, and even reptiles as second intermediate hosts, and aquatic birds and mammals as definitive hosts. Recently, E. trivolvis has gained attention due to the pathology it induces in larval amphibian hosts. Within the amphibian, E. trivolvis encysts within the kidney system, sometimes reaching extreme abundances (~1,000 cysts per frog). Large numbers of cysts, coupled with young, early developmental tadpoles can cause delayed growth and edema or swelling, and even mortality. Concerns over the impact of E. trivolvis on amphibian populations has led to studies on its influence on tadpole survival and physiology, competitive ability, and interactions with other environmental stressors including eutrophication and agricultural pollution. In general, species of Echinostoma are also useful subjects for laboratory and field research of host-parasite interactions in ecology, physiology, and immunology.

Contributed by Sarah Orlofske

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