Questionnaire-based survey on distribution of canine ocular thelaziosis in southwestern France

The distribution of Thelazia callipaeda, commonly known as "oriental eyeworm", has been considered for a long time to be confined to the former soviet Republics and Asia where the nematode causes infections in domestic and wild carnivores, rabbits and sometimes humans. However, since 2000, thelaziosis has been diagnosed in dogs and sometimes in cats from a growing number of European countries, including France. In 2006, a survey demonstrated that many autochthonous cases of canine thelaziosis were present in the department of Dordogne (southwestern France) in three hyperenzootic counties where strawberry production was predominant. The objective of the present study was to obtain an updated evaluation of the enzootic occurrence of T. callipaeda in France. In April 2016, an electronic questionnaire was sent to 1670 veterinary clinics from 24 French departments of southwestern France. Among 279 responses, 97 veterinary clinics reported cases of canine thelaziosis during the last 12 months. Most of them (72/97, 74.2%) reported a limited number of cases. Two veterinary clinics in previously-identified hyperenzootic counties of Dordogne reported the higher incidence (50 and 68 new cases annually). Noteworthly, two clinics located in another department (Landes) also reported many autochthonous cases (30 cases annually) demonstrating the existence of new enzootic foci. The present investigation confirmed that Dordogne is still an enzootic area of ocular thelaziosis and that the disease is spreading in new areas of southwestern France since a decade.