A new approach to outbreak management for bovine Cystic Echinococcosis cases in hypo-endemic areas.

Abstract

Cystic Echinococcosis (CE) surveillance in Italy is based on detection of its larval stage (hydatic cysts) at the slaughterhouse. In northern Italy, a hypo-endemic area, local health authorities investigate each individual farm with positive animals to treat their dogs with cestocidal drugs, but this system is time-consuming and poorly effective for bovine farms. The study applied a new approach based on targeted epidemiological surveys in areas with aggregation of bovine CE cases, and compared the outcome with that of two control areas with farms individually investigated. The presence of territorial cluster of bovine farms with CE cases was investigated for 3 consecutive years (2013-2014-2015) in a high-risk area of Veneto Region (north-eastern Italy), using a spatial scan statistic. Epidemiological investigations, consisting of a questionnaire survey and canine faecal samples collection, were conducted in cluster and control areas. All faecal samples were analyzed for taeniids eggs and positive samples were sequenced and identified. In total, 99 farms were surveyed and 208 faecal samples were retrieved from dogs. Sixty-two farms (42 bovine and 20 sheep) were investigated in cluster areas and 37 farms (33 bovine and 4 sheep) in control areas. Based on the results of the cestode egg isolation procedure, 14 animals (6.7%) were positive to taeniid eggs. For molecular analysis, two dogs resulted positive to Echinococcus granulosus, and seven to Taenia hydatigena. Twelve positive dogs were found in targeted survey areas and ten of these dogs were shepherd dogs, belonging to transhumant sheep flocks known to pass in cluster areas. The new approach demonstrated to successfully identify the probable source of infection of CE positive bovines. Most of positive dogs belonged to transhumant flocks, underlining the importance to include shepherd dogs in the surveillance system for CE.