"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

October 30, 2010

October 30 - Philophthalmus gralli

Continuing our theme of nasty places to have worms, how about under the eyelid?! Flukes of the genus Philophthalmus are found in the conjunctival sac of the eyes of many species of birds and rarely in humans. In this case, a rhea (Rhea americana) in a zoo had an unusually heavy infection of several hundred flukes in each eye. The intermediate hosts are aquatic snails. When the cercariae escape from the snail, they encyst on vegetation or occasionally at the surface of the water and the cysts are ingested by the final host, where they hatch and migrate to the eye.

Contributed by Mike Kinsella, photo by Melanie Church.


  1. Oooooh, very interesting -- a veterinarian with a strong stomach!

  2. i dont think parasites are disgusting.
    they are more like inspiring.they make you want to research,study and know about their little world which is hidden from us.
    thank you Anthony Leeuwenhoek,father of microscopy,for giving us the option to see things so small and beautiful.

  3. What happened to the rhea at the zoo? Does it still have the flukes?

  4. Andy- the vet (Melanie Church) cleaned out the eyes (there was more than one rhea infected). She was re-checking them this week.

  5. The rheas are doing so much better!!! We are trying a new topical drug to target the flukes. Hopes are to publish our findings...will keep you posted. :)
    Thanks for the votes, what an honor to have the Philophthalmus gralli voted as "Parasite of the Year"!

  6. This blog could be the find of the year, along with this particular parasite, which is deserving of such a title!

  7. i have seen this kind of worm in many infected hen and duck. but i don't know what it is, all what i observe they suffer alot and some time can even walk, the infected eye was always close. thanks for the enlightenment