Cystic echinococcosis in Lebanese animals and humans

Cystic echinococcosis (CE) is a zoonotic disease caused by the species complex of Echinococcus granulosus sensu lato (s.l), endemic in Middle East and the Mediterranean basin, where pastoral activity is widespread. Despite the chronic endemicity of the disease in Lebanon and neighboring, recent data are scant. This doctoral thesis aims to to evaluate the current epidemiology of CE in sheep and goats of Lebanon, assess the demographic and epidemiologic features of human CE surgical cases over a 14-year period in the five main regions of Lebanon and determine the infecting genotypes. A multidimensional approach combining post mortem inspection of slaughtered animals, data collection of surgically confirmed cases of human CE from five anatomo- pathology laboratories, and molecular diagnosis of the parasite was conducted. From 2018 to 2020, on 369 slaughtered sheep and 335 goats examined, 62.9% of sheep and 20.9% of goats were found positive for CE. The presence of hydatids varied between organs, showing higher prevalence in liver of sheep and in lungs of goats, however, higher fertility rate of hydatid cyst was observed in lungs for both animals. In humans, from 2005 to 2018, a total of 894 surgically confirmed cases of CE were recorded, with an increasing incidence from 0.53 to 1.94 cases/100,000 inhabitants in 2005 and 2018, respectively. The mean annual surgical incidence was 1.23/100,000 inhabitants. CE is present in Lebanon with an uneven distribution with higher prevalence in Bekaa (29.0%), a rural region where sheep raising is widespread. CE cases were more common in females than in males and a high burden of infection was reported for the age group of 30-39 years. Besides, 66.7% of the cases expressed only liver complications, 20.5% were related to lungs, 7.8% presented cysts in other organs, and 1.3% showed multiple localizations. Molecular diagnosis showed that the majority of isolates were identified as E. granulosus sensu stricto and only one isolate from goat was identified as E. canadensis. The current study is a step forward to fill the gap of knowledge for the CE in Lebanon and revealed for the first time the presence of three different genotypes G1, G3 and G7.