Questionnaire survey of Thelazia callipaeda prevalence in Italy and vector samplings indicate Lazio region as a hot-spot of thelaziosis

INTRODUCTION. Thelaziosis is a zoonotic disease widespread in Asia and an emerging threat in Europe caused by the oriental eyeworm Thelazia callipaeda, transmitted through lachryphagous activity of Phortica variegata (Otranto et al., 2005 Trends Parasitol. 21: 1-4). In European countries, increasing cases of thelaziosis have been registered during last 20 years in domestic and wild animals, respectively (do Vale et al., 2020 Parasite. 27). In addition, several reports of this disease are described in humans, with 11 cases diagnosed in Europe until now. In order to evaluate the burden of this disease in Italy, an on-line survey has been administered on veterinarians. This information has also been associated to T. callipaeda prevalence in vector populations focusing on Lazio region. MATERIALS AND METHODS. A questionnaire was distributed through the Federazione Nazionale dei Medici Veterinari Italiani requesting information about clinical records of thelaziosis cases. Sampling of lachryphagous drosophilids was conducted in 4 areas of Lazio region: Manziana (RM), Gattaceca (RM), Nomentum Park (RM), Foglino (RM) and Turona park (VT). Collected specimens were morphologically identified and molecularly tested by PCR (cox1) to detect T. callipaeda (Otranto et al., 2005 Mol Cell Probes. 19: 306-13). RESULTS AND CONCLUSIONS. A total of 408 records were obtained from questionnaire administration, reporting an overall presence of T. callipaeda in 15 out of 17 regions, with higher participation in Lazio (66), Emilia-Romagna (65) and Veneto (57). Most thelaziosis cases have been observed in dogs (82%), followed by cats (10%) and a few other animal cases. The majority of detections were in Lazio (27%) and Piemonte (25%). The first clinical detection dates 1980 in Frosinone (Lazio), with an increasing trend through the years, particularly after 2015. A total of 1316 lachrypagous P. variegata were collected, of which 23 (1.7%; 95% CI: 0.6 – 2.8%) tested positive for T. callipaeda, particularly in Manziana, were the eyeworm was stably diagnosed from 2017 to 2020. These results indicate that T. callipaeda is widespread among mammal hosts throughout Italy, particularly in Lazio region, which seems to be a hot-spot of transmission for this disease.