Thelaziasis

A parasitic infection caused by Thelazia worms

Thelaziasis is an ocular parasitic infection caused by nematodes of the genus Thelazia. These parasites are commonly referred to as "eye worms" and primarily affect the eyes and associated tissues of various mammals, including humans, dogs, and cats.

Etiology

Thelaziasis is caused by several species of the genus Thelazia, with Thelazia callipaeda and Thelazia californiensis being the most common culprits. These nematodes are transmitted by flies that act as intermediate hosts. The flies feed on the tears and other secretions of the eyes, depositing infective larvae that mature into adult worms in the conjunctival sac.

Clinical Presentation

Infected individuals may present with a range of symptoms, including:

• Conjunctivitis
• Excessive tearing (epiphora)
• Foreign body sensation
• Photophobia
• Keratitis

In severe cases, the presence of the worms can lead to corneal ulceration and impaired vision.

Diagnosis

Diagnosis of thelaziasis is primarily clinical, based on the observation of the worms in the conjunctival sac or on the surface of the eye. The worms are typically visible to the naked eye and can be removed manually using fine forceps.

Treatment

The primary treatment for thelaziasis involves the mechanical removal of the worms from the eye. This is often followed by topical administration of antiparasitic medications such as ivermectin or albendazole to ensure complete eradication of the parasites.

Prevention

Preventive measures include controlling the population of the fly vectors and protecting the eyes from exposure to these flies. In endemic areas, regular veterinary check-ups for pets can help in early detection and treatment.

Epidemiology

Thelaziasis is more prevalent in certain regions of Asia and Europe, with sporadic cases reported in other parts of the world. The distribution of the disease is closely linked to the presence of the fly vectors.

Related pages

• Nematode infections
• Parasitic diseases
• Ophthalmology