"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

May 20, 2010

May 20 - Plagiorchis vespertilionis

I didn't intend to do this, but the parasites so far this week have all started with "P" - so let's keep that up! This is Plagiorchis vespertilionis, a trematode fluke. These parasites have complex life cycles which go from snails to insects such as caddisflies or dragonflies and then eventually make their way to insectivorous bats when they gobble these bugs up. A recent paper reported a case of this parasite in a Korean man, but how this individual became infected is not clear. The man did not admit to eating dragonflies, nor being an Ozzy Osborne impersonator, but he had recently eaten raw freshwater fish (this is never a good idea, by the way...). Thus, either there is convergence between a species that looks a lot like P. vespertilionis and one that is found in fish, or the host use patterns of this parasite are much more general than originally thought.

The image is from this paper, which named a subspecies of the parasite in American bats.


  1. Maybe the fish had eaten a caddisfly larva.

  2. When cleaning fish one often sees caddisfly larvae in the gut. A possible route of infection is ingestion of the stomach contents of a fish.

  3. Yes, this is likely the mode of transmission. My money would still be on there being at least two species involved here given the hosts and geography. Someone should follow up!