Anisakidae and Raphidascaridae are marine nematodes present in a wide range of fish hosts, which may cause gastro-intestinal complaints and/or allergy in human, in addition to economic losses for the industry. Data regarding the presence of these parasites in fish for the Belgian market is currently missing; therefore, our aim was to investigate the presence and intensity of ascaridoids in a wide range of commercially fish species. A total of 415 fish samples, belonging to 36 different fish species, were collected from a Belgian whole-sale company. Ascaridoid larvae from the viscera (if present) and the muscles were collected by enzymatic digestion and the prevalence, median intensity, mean number of larvae per 100 g infected muscle, and localisation were determined. An overall prevalence of 53% [95%-CI: 42-63%] in the viscera and 27% [95%-CI: 23-32%] in the muscles was observed. Infection in the muscles varied between the fish species; no larvae were detected in 13 fish species, while a high prevalence (>78%) was observed in pollack, halibut, and gurnard. Most samples originated from the Northeast Atlantic Ocean, with the highest prevalence in the muscles observed in the Barents & Norwegian Sea (65% [95%-CI: 38-86]). Muscle samples were, if possible, divided in an anterior region, belly flap, medial region, and posterior region, with the most infections and larvae found in the belly flaps. In all samples, a total of 2569 larvae were recovered, with 1594 larvae originating from the viscera and 975 from the muscles; with an average of two larvae per 100 g infected fillet detected. Larvae were morphologically identified, and a subgroup was further confirmed using PCR/RFLP, resulting ultimately in the identification of Anisakis simplex s.s. (1853 larvae), A. pegreffii (137), A. simplex/pegreffii hybrid genotype (38), Pseudoterranova decipiens (160) and Hysterothylacium aduncum (380). This study demonstrates that ascaridoid larvae are highly prevalent in different fish species on the Belgian market.

中文翻译：

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商业鱼中的类螨虫：运往比利时市场的整条鱼和鱼片的发生，强度和位置。

Anisakidae和Raphidascaridae是广泛存在于鱼类寄主中的海洋线虫，除了对行业造成经济损失外，还可能引起胃肠道不适和/或人类过敏。目前缺少关于比利时市场鱼类中这些寄生虫的存在的数据；因此，我们的目的是调查各种商业鱼类中类胡萝卜素的存在和强度。从一家比利时批发公司收集了总共415种鱼样本，分别属于36种不同的鱼类。通过酶消化从内脏（如果存在的话）和肌肉中的类螨虫幼虫收集，并测定其患病率，中值强度，每100g感染的肌肉中的幼虫平均数和定位。内脏整体患病率为53％[95％-CI：42-63％]，27％[95％-CI：在肌肉中观察到[23-32％]。鱼类之间的肌肉感染情况不同。在13种鱼类中未检测到幼虫，而在波拉克，大比目鱼和鱼中发现了很高的流行率（> 78％）。大多数样品起源于东北大西洋，在巴伦支海和挪威海中观察到的肌肉患病率最高（65％[95％-CI：38-86]）。如果可能，将肌肉样品分为前部区域，腹部皮瓣，内侧区域和后部区域，在腹部皮瓣中发现的感染和幼虫最多。在所有样本中，共回收到2569幼虫，其中1594幼虫来自内脏，而975则来自肌肉。每100 g受感染的鱼片平均有两个幼虫。通过形态学鉴定幼虫，并使用PCR / RFLP进一步确认亚组，最终鉴定出了Anisakis simplex ss（1853幼虫），A。pegreffii（137），A。simplex / pegreffii杂交基因型（38），Pseudoterranova decipiens（160）和Hysterothylacium aduncum（380）。这项研究表明，在比利时市场上，不同种类鱼类中的类胡萝卜素幼虫高度流行。