Transmission of the eyeworm Thelazia callipaeda: between fantasy and reality

Abstract

Background: Thelazia callipaeda is transmitted by Phortica variegata, a drosophilid that feeds on lachrymal secretions of mammals. Scientific information on human thelaziosis is still relatively limited, mainly for physicians and ophthalmologists. Indeed, the literature is full of misleading information on the transmission of T. callipaeda to humans.

Findings: A recent paper reported a case of human intraocular infestation in a patient from Karnataka. The information presented in that article as well as in other articles in the international literature is outdated and incorrect in several instances, mostly regarding to the localization of T. callipaeda in the host, its biology and routes of transmission.

Conclusions: Physicians and ophthalmologists should be aware that T. callipaeda is larviparous and transmitted exclusively by secretophagous flies. These flies buzz around the eyes of animals and humans at the daytime, landing on the eyes and releasing the infective larvae on the host conjunctiva. That is the only possible way of transmission of T. callipaeda.

Fig. 1

Dog eye with Thelazia callipaeda worms. Nematodes in the conjunctiva of a dog with a severe conjunctivitis and follicular hypertrophy of the conjunctiva