Autochthonous infection of buffaloes and cattle by Fasciola hepatica in Minas Gerais, Brazil

Fasciola hepatica is a digenetic trematode that parasitizes the bile ducts of different species of vertebrate hosts. In Brazil, this parasitosis is expanding and occurrences have been reported in the southern, southeastern, central-western and northeastern regions. This study aimed to report the first case of naturally infection of buffaloes by this parasite in the state of Minas Gerais. A total of 250 stool samples, 176 from cattle and 74 from buffaloes, from the districts of São José da Lapa and Pedro Leopoldo, were examined. Also, 402 snails of the genus Lymnaea were collected on the same farms and the viability of the eggs from naturally infected buffaloes and cattle and the susceptibility of the snails to infection were tested. A total of 54 animals were found to be positive, 33 cattle (18.75%) and 21 buffaloes (28.37%), and two molluscs showed immature forms of F. hepatica. In experimental infection of specimens of Lymnaea, cercariae were obtained through spontaneous elimination from the 57th day post-infection onwards. The importance of this first case report can be emphasized because it confirms that this parasite is being dispersed in municipalities in this state that had previously been considered to be unaffected.

肝片形吸虫（Fasciola hepatica）是一种复殖吸虫（digenetic trematode），可寄生于多种脊椎动物宿主的胆管内。在巴西，该寄生虫病的流行范围正持续扩张，南部、东南部、中西部及东北部地区均已有病例报道。
本研究旨在报道巴西米纳斯吉拉斯州（Minas Gerais）首例水牛自然感染该寄生虫的病例。研究共采集了来自圣若泽达拉帕（São José da Lapa）与佩德罗莱奥波尔杜（Pedro Leopoldo）地区的250份粪便检测样本，其中176份取自牛、74份取自水牛。同时，在上述养殖场采集了402只椎实螺属（Lymnaea）螺类，并针对两项内容开展检测：自然感染的水牛与牛的虫卵活力，以及该螺类对寄生虫感染的易感性。
最终共检出54份阳性样本，其中33份为牛（阳性率18.75%）、21份为水牛（阳性率28.37%），另有2只软体动物（molluscs）检出肝片形吸虫的未成熟虫体。在对椎实螺的人工感染实验中，感染后第57天起即可通过自发排虫获取尾蚴（cercariae）。
本首例病例报告的重要意义在于，证实该寄生虫已扩散至该州此前被认为无该寄生虫分布的多个县域。