Human Thelaziasis, Europe

Domenico Otranto; Moreno Dutto


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

In This Article


We report human infection by T. callipaeda in Italy and France in the same area where canine thelaziasis had been reported. These infections highlight the importance of including this arthropod-borne disease in the differential diagnoses of bacterial or allergic conjunctivitis. All cases of human thelaziasis were reported during the summer months (June-August), which is the period of T. callipaeda vector activity (late spring to fall in southern Europe).[7] The seasonality of human thelaziasis may impair correct etiologic diagnosis of this disease because spring and summer are the seasons in which allergic conjunctivitis (e.g., by pollens) occurs most frequently. This finding is particularly important when infections are caused by small larval stages that are difficult to detect and identify. Furthermore, clinical diagnosis of human thelaziasis is difficult if only small numbers of nematodes are present because clinical signs related to an inflammatory response mimic allergic conjunctivitis, especially when they are associated with developing third- or fourth-stage larvae.

Untimely or incorrect treatment of the infection may result in a delay in recovery, mainly in children and the elderly, who are most likely to be exposed to infection by the fly. Although treatment for canine infection with T. callipaeda with topical organophosphates, 1% moxidectin, or a formulation containing 10% imidacloprid and 2.5% moxidectin is effective, mechanical removal of parasites in humans remains the only curative option.[3] Thus, prevention of human thelaziasis should include control of the fly vector by use of bed nets to protect children while they are sleeping and by keeping their faces and eyes clean. Genetic identification of haplotype 1 has shown that this is the only haplotype circulating in animals (i.e., dogs, cats, and foxes) in Europe.[11] This finding confirms the metazoonotic potential of Thelazia spp. infection and the need to treat infected domestic animals, which may act as reservoirs for human infection.


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