Abstract
Purpose
To describe an unusual case of ocular thelaziosis due to Thelazia callipaeda , an underdiagnosed and emerging zoonosis.
Observations
We report an 81-year-old woman presented to our emergency department with a week long history of bilateral redness and tearing that had not improved despite antibiotics and corticosteroid topical treatment. Slit-lamp biomicroscopy showed signs of bilateral conjunctivitis and mucopurulent discharge in fornices. Under the upper tarsal conjunctiva of the left eye, two filiform worms were identified, which were removed and sent on wet mount slides for microscopic examination and genetic identification. The rest of the ophthalmoscopic examination was rigorously normal. Polymerase chain reaction (PCR) assay turned positive for Thelazia callipaeda . During further questioning, the patient reported that she had been on summer vacation in contact with dogs which were infected with eye worms.
Conclusions and Importance
Ocular thelaziosis is an emerging zoonosis in Spain, but also in the rest of the world. Ophthalmologists should include ocular thelaziosis in humans as a possible cause of conjunctivitis, tearing, and corneal ulcer, thus avoiding underdiagnosis and inappropriate treatments. The epidemiology of the disease makes anamnesis essential. A confocal biomicroscopy is a useful device for identifying this eyeworm but the definitive diagnosis will be made taking into account the morphological identification under microscope, together with the molecular identification by PCR techniques.
1
Introduction
Thelaziosis is a zoonosis caused by nematodes belonging to the genus Thelazia (Spirurida: Thelaziidae) , transmitted by Musca fly and drosophilid vectors which deposits the larvae in the host’s conjunctiva. ,
This parasitosis has been reported in some exceptional human cases and three species have been identified in pathogenesis: Thelazia callipaeda , Thelazia californiensis and Thelazia gulosa. Thelazia callipaeda is the most common cause of thelaziosis in humans and two intermediate hosts have been identified, Phortica variegata in Europe and Phortica o kadai in Asia, which feeds on lacrimal secretions releasing larvae in human’s conjunctiva.
Adults worms located in conjunctival sac produces tearing, itching, foreign body sensation, photophobia or signs of conjunctivitis and nematodes can be observed with slit-lamp biomicroscopy under tarsal conjunctiva. The definitive diagnosis will be made taking into account the morphological characteristics evidenced by vision under microscope, together with the molecular identification by polymerase chain reaction (PCR). ,
It is important to know this entity in order to include it in the differential diagnosis of red eye in patients with epidemiological history of contact with animals and also in those who, despite not having been in contact with animals, have stayed in rural or forested areas where Thelazia callipaeda vectors are available.
2
Case report
An 81-year-old woman presented to our emergency department with a 1-week history of red eyes, photophobia and tearing that had not improved despite antibiotics and corticosteroid topical treatment. Best-corrected visual acuity was 10/200 in right eye and 20/100 in left eye (she suffered from bilateral optic atrophy due to childhood meningitis), showing signs of bilateral conjunctivitis with mucopurulent discharge in conjunctival fornices ( Fig. 1 ).
In the left eye under the upper tarsal conjunctiva, 2 whitish filiform worms 5 mm long were identified, which after instillation of topical anesthetic, were removed without incident with tweezers ( Fig. 2 ). The eyeworms were sent, on wet mount slides, to the microbiology department for microscopic examination and molecular identification ( Fig. 3 ). The rest of anterior chamber and fundus examination did not show any interesting findings.
