Human Thelaziasis, Europe

Domenico Otranto; Moreno Dutto


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]


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as: