Abstract：
Adenocephalus pacificus is a tapeworm parasitic of marine mammals and the main agent of human diphylobothriosis caused by consumption of raw or undercooked marine fishes, being considered as a reemerging disease. Despite having a broad distribution in marine mammals in both hemispheres, plerocercoid larvae in fish have only been reported in the Pacific Ocean, in Peruvian waters, from where most human cases are known. In Argentine waters larval stages of Diphyllobothriidae have been recorded in Merluccius hubbsi, a main fish resource mostly exported frozen, headed and gutted (H&G) or as fillets; therefore, the possible presence of A. pacificus in edible products, and the extent of the risk of parasitism for humans becomes of health and commercial relevance. With the aim of detecting and identifying potentially zoonotic diphyllobothriids and quantifying infection levels in viscera and fillets of hakes, 43 entire fish, 471 H&G, and 942 fillets obtained from research cruises in 2019 and 2021 from the southern Argentine Sea (44-53°S; 63-68°W) were examined by transillumination and under stereoscopic microscopy. Plerocercoids were recovered at low prevalence and mean abundance in entire fish (13.95 % and 0.35) and H&G fish (2.76 % and 0.03) but no larval worms were found adhered to musculature or peritoneum, furthermore, no larvae were found in the fillets. Larvae were genetically identified, based on sequences of the large subunit ribosomal RNA nuclear gene (lsrDNA) and the cytochrome c oxidase subunit 1 (cox1) mitochondrial gene, as members of A. pacificus, representing the first report of this species in a fish host outside South American Pacific coasts. No spatial nor bathymetric patterns in parasite burdens were observed across sampling sites, but prevalence increased with fish size. The recorded low parasite burdens, the absence of infective stages in fillets and the fact that most products are commercialized deeply frozen, diminish the risk of parasitism for consumers to a minimum. However, the identification of this zoonotic agent and the assessment of its distribution in fish products are a first indispensable step for the design of efficient and suitable measures, such as freezing or cooking meet, to ensure the prevention of human infections.
摘要：
氨甲虫是海洋哺乳动物的寄生虫，是由于食用生的或未煮熟的海洋鱼类而引起的人类双藻病的主要病原体，被认为是一种重新出现的疾病。尽管在两个半球的海洋哺乳动物中分布广泛，仅在太平洋报道了鱼类中的plerocercoid幼虫，在秘鲁水域，从那里知道大多数人类病例。在阿根廷水域，在Merlucciushubbsi中记录了二叶虫科的幼虫阶段，主要的鱼类资源主要是冷冻出口，头部和内脏(H&G)或作为鱼片；因此，可食用产品中可能存在A.pacificus，以及寄生虫对人类的风险程度与健康和商业相关。为了检测和鉴定潜在的人畜共患的双叶病，并量化内脏和鱼片的感染水平，43整条鱼，471H&G,通过透照和立体显微镜检查了2019年和2021年从阿根廷南部海域（44-53°S；63-68°W）的研究航行中获得的942个鱼片。在整个鱼（13.95％和0.35）和H＆G鱼（2.76％和0.03）中，在低患病率和平均丰度下恢复了plerocercoids，但未发现幼虫蠕虫粘附在肌肉组织或腹膜上，此外，鱼片中没有发现幼虫。幼虫经过基因鉴定，基于大亚基核糖体RNA核基因（lsrDNA）和细胞色素c氧化酶亚基1（cox1）线粒体基因的序列，作为A.Pacificus的成员，代表该物种在南美太平洋沿岸以外的鱼类宿主中的第一份报告。在采样点没有观察到寄生虫负担的空间或测深模式，但是患病率随着鱼的大小而增加。记录的低寄生虫负担，鱼片中没有感染阶段，以及大多数产品被深度冷冻商业化的事实，将消费者的寄生风险降至最低。然而,识别这种人畜共患病原体并评估其在鱼类产品中的分布是设计有效和适当措施的第一步，例如冷冻或烹饪，确保预防人类感染。
