Monsters Inside Us: Avian Eye Flukes
What could be creepier than the thought of having worms in your eye? This past year at International Bird Rescue we have seen quite a few cases of weird and horrifying eye worms in our patients. We don’t know if the increase is some side effect of California’s drought perhaps concentrating larger numbers of birds in smaller bodies of water, or some other factor. But in honor of Halloween we thought we’d share some knowledge about parasites of the eye. Knowledge is a good thing, right?
Philophthalmus gralli is a trematode (aka fluke) parasite that affects many species of birds. These worms look like miniature flatworms that have two suckers. The adult worms attach inside the bird’s eyelids in and around and on the conjunctiva and under the nictitans (3rd eyelid), where they suck blood and make lots of babies while irritating the heck out of the eye, of course. The fluke eggs hatch as they are released directly into water, where they find a snail they need for their next life stage. The ‘ripe’ larvae that leave the snail later encyst on aquatic vegetation, and wait for another bird to eat the plant. Once in the bird’s mouth they quickly burst free of their shell and make their way to their happy place in the eyelids of the bird to become an adult.
Yes, people can get this disease…but humans don’t get these dastardly worms directly from the birds! Instead, we can catch them from eating aquatic vegetation infested with worm cysts. We thankfully don’t have to worry too much about staff and volunteer exposure to these parasites since our pools lack a population of snails for the worms to complete their life cycle…but ewww!
Read more about their life cycle here: https://www.cdc.gov/dpdx/philophthalmiasis/index.html