Cystic echinococcosis in Sardinia: farmers' knowledge and dog infection in sheep farms

Abstract

Cystic Echinococcosis (CE) is one of the most widespread parasitic diseases in Sardinia, the second largest Mediterranean island where almost 3,558,000 milk sheep were raised extensively. The aim of this survey was to evaluate the level of farmers' knowledge on CE transmission, focusing on the role of human to facilitate the persistence of this zoonosis in Sardinia after 14 years after the last campaign against CE. The other goal of the survey is to update on presence of Echinococcus granulosus in its definitive hosts through three ELISA coproantigen tests. An interview was carried out with 172 farmers. The questionnaire was designed to include possible factors associated with the transmission of Echinococcosis: ownership and number of dogs, the use of anthelmintic drugs against dog cestode, frequency of anthelmintic treatment in dogs, home slaughtering and offal disposal. Individual faecal samples were retrieved from 300 dogs, and after a preliminary macroscopic examination to discover adult worms and/or proglottids, was submitted to copromicroscopic examination. Coproantigens were then extracted according to the protocol described by Allan et al. (1992), and subsequently stored at -20°C until use. Faecal soluble antigens from E. granulosus were detected using three different ELISA coproantigen assays: (a) the commercially produced Chekit Echinotest (Bommeli, Bern, CH) based on polyclonal antibodies against adult excretory/secretory (E/S) antigens; (b) a sandwich ELISA that uses rabbit polyclonal antibodies against adult E/S antigens and biotinylated monoclonal antibody EmA9 produced against adult Echinococcus multilocularis somatic extract (Malgor et al., 1997); and (c) a sandwich assay that uses monoclonal antibody EgC3 produced by immunization with adult E. granulosus E/S products (Casaravilla et al., 2005). Questionnaire results reveal that on all farms home-slaughtering was done, and offal was used as dog meal raw (17%) or after boiling (37%), discarded in the trash (23%), or buried superficially (15%). Most farmers (69%) declared to deworm their dogs, but only 10% used cestodicidal drugs. The coprological survey of 300 farm dogs using sedimentation, flotation and three different coproantigen (CA) ELISAs resulted in a faecal prevalence of 8.3% for taeniid eggs, while the CA tests gave prevalences of 3% (Chekit Echinotest, Bommeli), 6% (EmA9 sandwich ELISA) and 10% (EgC3 sandwich ELISA). Our results show that this is not only an educational problem, but also an economic one, stressing the need that future control plans should follow an integrative approach including veterinary and medical services, farmers, breeders' associations and the Government.