Human Thelaziasis, Europe

Domenico Otranto; Moreno Dutto

Disclosures

Emerging Infectious Diseases. 2008;14(4):647-649. 

In This Article

The Study

From June 2005 through August 2006, a total of 4 patients with human thelaziasis were referred to the Department of Emergency and Admissions at Croce and Carle Hospital in Cuneo, Italy, for consultation. The 4 male patients (age range 37-65 years) lived in northwestern Italy (43°N, 6°E) and southeastern France (46°N, 9°E), where infections had been reported in dogs, cats, and foxes.[9,12] All patients had similar symptoms (exudative conjunctivitis, lacrimation, and foreign body sensation) for a few days to weeks before referral ( Table 1 ). All patients required medical attention during the summer (June-August 2005 and 2006) and reported floating filaments on the eye surface. A medical history was obtained for 3 of the patients. The other patient (patient 2, a homeless man) was referred to a physician at the local social services in Nice, France, for severe mental disorders, poor hygiene, and diabetes ( Table 1 ). Infections in patient 2 were diagnosed 1 month apart in each eye (June and July 2005; referred to as patient 2a and 2b). None of the patients had had any eye disease or had traveled outside their area of residence, with the exception of patient 1 who had gone trekking in the woods in Tenda (Piedmont region, Italy) ~3 weeks before the onset of symptoms.

Eye examinations showed thin, white nematode(s) on the conjunctival fornix of the affected eye. Nematodes were removed with a forceps after local anesthesia (1% novocaine) was administered. The nematodes were stored in 70% ethanol until they were morphologically identified and analyzed. After the parasites were removed from the eyes, antimicrobial eye drops were prescribed for ~7 days. Ocular symptoms disappeared within 2-3 days.

Collected nematodes were identified based on morphologic keys.[13,14] T. callipaeda nematodes have a serrated cuticle (Figure 2, panel A), buccal capsule, mouth opening with a hexagonal profile, and 6 festoons. Adult females are characterized by the position of the vulva, located anterior to the esophagus-intestinal junction, whereas males have 5 pairs of postcloacal papillae. To confirm morphologic identification, specimens from patients 2 and 4 were analyzed as previously described.[11] Genomic DNA was isolated from each nematode, and a partial sequence of the mitochondrial cytochrome c oxidase subunit 1 (cox1, 689 bp) gene was amplified by PCR. Amplicons were purified by using Ultrafree-DA columns (Amicon; Millipore, Bedford, MA, USA) and sequenced by using an ABI-PRISM 377 system and a Taq DyeDeoxyTerminator Cycle Sequencing Kit (Applied Biosystems, Foster City, CA, USA). Sequences were determined in both directions and aligned by using the ClustalX program.[15] Alignments were verified visually and compared with sequences available for the cox1 gene of T. callipaeda (GenBank accession nos. AM042549-556).

A) Female Thelazia callipaeda isolated from patient 4. The posterior end is on the left and the anterior end is on the right (magnification x 200). Scale bar = 500 µm. B) T. callipaeda mature first-stage larvae in the distal uterus (magnification x100). Scale bar = 30 µm.

A total of 6 adult nematodes were morphologically identified as T. callipaeda ( Table 1 ). A mature female nematode (patient 4) had embryonated eggs in the proximal uterus and larvae in the distal uterus (Figure 2, panel B). This suggested that a male worm was present, which had been rubbed out of the eye before symptoms occurred or had remained undetected. Sequences obtained from nematodes were identical to the sequence of haplotype 1 of T. callipaeda (GenBank accession no. AM042549).[11]

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