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Avian Philophthalmus

Other Names: Ocular Trematodiasis

Avian philophthalmus is a parasitic eye infection of birds caused by the trematode, Philophthalmus. Philophthalmus, also referred to as the avian eye fluke, affect domestic and wild birds worldwide, especially waterbirds and wading birds (e.g., gulls, ducks, geese, herons). There have also been sporadic reports of cases occurring in humans.Philophthalmus invade the conjunctival and orbital tissues of their host, resulting in conjunctivitis, epiphora, subconjunctival hemorrhage, and itching/swelling of the eyelids.

Chickens become infected through eating intermediate hosts, encysted metacercariae on substrates (vegetation, crustacean shells, etc), or direct contact with cercariae or metacercariae in water. Intermediate hosts include snails, bivalves, aquatic insect larvae, crustaceans, frogs, fish, and reptiles. If ingested, Philophthalmus migrates from the esophagus to the nasal passages and ultimately to the eyes of the bird.

Avian philophthalmus is diagnosed by your veterinarian through an ophthalmic exam and conjunctival sac lavage. The lavage provides fluid which can be examined using a microscope for the presence of Philophthalmus eggs. The only effective treatment for avian philophthalmus is removing Philophthalmus from the bird's eye with forceps. Praziquantel and fenbendazole are ineffective.

Clinical Signs

Flukes visible in eye
Eye discharge
Frequently scratching eye
Swelling of eyelid


  • History
  • Ophthalmic exam
  • Conjunctival sac lavage

Reported Cases

  • Case 1: Philophthalmus in a Rhea A 2-year-old female Greater Rhea presented with a 2-month history of blepharospasm and conjunctival hyperemia in both of her eyes. She was given albendazole, enrofloxacin, and doxycycline hycrate which didn't resolve the issue. 3 weeks later, another Rhea developed the same clinical signs. Conjunctival biopsies showed nonspecific, reactive inflammatory changes with trematodes attached to the conjunctival epithelium. While the Emus were under anesthesa, the trematodes were removed. One Emu had a total of 252 trematodes removed from both eyes, and the other Emu had over 675 throughout both eyes. Compounded praziquantel 1% ointment was prescribed to be applied to the bird's eyes every 12 hours, as post-surgical medication. Both Rheas had a smooth recovery from the anestheia, however, 2 hours later, one of the birds died. Ref


Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
Physical removal with forceps.



Don't allow chickens access to areas where freshwater or marine snails live.

Scientific References

Risk Factors

  • Allowing chickens access to where freshwater or marine snails live.

Also Consider