Anisakiasis is a gastrointestinal disease caused by parasitic anisakid nematodes, mainly Anisakis simplex sensu stricto (A. simplex). Anisakiasis is prevalent in Japan and approximately 40% of anisakiasis cases in Tokyo occur through the consumption of raw or marinated mackerel. However, in 2018, there was a sudden increase in the number of the food poisoning cases in Tokyo caused by consumption of skipjack tuna (Katsuwonus pelamis). Therefore, we investigated anisakiasis cases resulting from ingestion of skipjack tuna in Tokyo, and surveyed the presence of Anisakis larvae in skipjack tuna in 2018 and 2019. Nineteen samples from 15 patients (13 in 2018 and 2 in 2019) with anisakiasis surely caused by ingestion of skipjack tuna were all identified as A. simplex. The higher mean abundance of Anisakis simplex larvae in skipjack tuna muscle in May 2018 (1.30; 13 larvae/10 fishes) compared to that in the other periods was regarded as a contributing factor in the increase in anisakiasis cases by ingesting skipjack tuna in 2018. To verify whether Anisakis larvae migrate from the visceral organs to the muscle during the period from fishing on the boat until processing for sale, the number of Anisakis larvae in skipjack tuna caught from August to November 2018 was investigated by removing the visceral organs at three different timings, i.e., immediately after catching, after landing, and after transport to the laboratory. Anisakis larvae were detected in the muscle irrespective of the timings at which visceral organs were removed. All larvae from the muscle were detected only from the ventral part and were identified as A. simplex. We thus consider that avoiding raw consumption of the ventral muscle should be an effective measure to prevent anisakiasis.

Anisakiasis是一种由寄生的Anisakid线虫引起的胃肠道疾病，主要是Anisakis simplex sensu stricto（A. simplex）。茴香病在日本很普遍，东京大约40％的茴香病病例是通过食用生的或腌制的鲭鱼而发生的。然而，在2018年，由于食用skip鱼（Katsuwonus pelamis）而导致的东京食物中毒案件突然增加。因此，我们调查了由于吞食东京skip鱼而导致的茴香病病例，并调查了茴香鱼的存在幼虫鲣鱼在从与异尖线虫病15名患者（13，2018年和2 2019年）由鲣鱼的摄入肯定造成2018年和2019年十九样品所有鉴定为A.单纯形。与其他时期相比，2018年5月skip鱼金枪鱼肌肉中Anisakis单纯形幼虫的平均丰度较高（1.30; 13尾鱼/ 10条鱼），这被认为是2018年通过摄入skip鱼而导致肛门炎的病例增加的原因。为了验证在从捕鱼到出售的过程中，茴香树的幼虫是否从内脏器官迁移到肌肉，茴香树的数量2018年8月至2018年11月在skip鱼中捕捞的幼虫在三个不同的时间进行了调查，即在捕捞后立即着陆，着陆后以及运往实验室后取出内脏器官。不论内脏器官切除的时机如何，都可以在肌肉中检测到凤梨幼虫。仅从腹侧部分检测到所有来自肌肉的幼虫，并被鉴定为单纯曲霉。因此，我们认为避免腹肌的原始消耗应是预防麻醉的有效措施。