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Avian Philophthalmiasis

Other Names: Ocular Trematodiasis

Avian philophthalmiasis is the name of the disease caused by infestation with the avian eye fluke, Philophthalmus gralli that invade the conjunctival and orbital tissues of the eyes of domestic and wild birds. This eye fluke causes conjunctivitis and keratitis (inflammation of the cornea). In severe cases, corneal ulcers, perforation and blindness may also occur. There has been an increase in reports of avian philophthalmiasis in captive and wild birds, especially ostriches, tinamus major birds, and greater Rheas. The most frequent clinical signs observed in infested birds include conjunctivitis, epiphora (excessive lacrymation), pruritus (itching), blepharitis, ocular discharge, blepharospasm (involuntary eye closure), subconjunctival hemorrhage, and swelling of the eyelids.

How the Avian Eye Fluke is Transmitted to Chickens


Mollusks, snails, bivalves, aquatic insect larvae, crustaceans, frogs, fish and reptiles serve as intermediate hosts of P. gralli. Two species of mollusks, the Red-rim Melania (Melanoides tuberculata) and the Quilted melanie (Tarebia granifera) in particular. P. gralli is transmitted to chickens through ingestion of the host or direct contact with them in the water.

Diagnosis and Treatment of Avian Philophthalmiasis


Avian philophthalmiasis is diagnosed by your veterinarian through an ophthalmic exam. P. gralli can be visualized in the conjunctival sac and under the third eyelid. Treatment has to be performed by your veterinarian. It consists of the mechanical removal of P. gralli with a swab or forceps and/or by flushing the conjunctival sac of the eyes.

Clinical Signs

Conjunctival redness
Corneal opacity
Ocular discharge
Frequent scratching of eyes
Swelling of eyelid

Diagnosis

  • Ophthalmic exam

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

Treatment

NameSummary
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.
Mechanical removal (which needs to be performed by your veterinarian) with a swab or forceps and/or by flushing the conjunctival sac of the eyes.

Support

Prevention

Restrict your flock's access to freshwater sources, especially in areas Tarebia granifera and Melanoides tuberculata are present.

Scientific References

Risk Factors

  • Allowing chickens access to freshwater sources, especially in areas Tarebia granifera and Melanoides tuberculata are present.

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