科学美国人60秒 寿司里为什么有虫子？（在线收听）

I'm a big fan of sushi and ceviche, so I was alarmed to see the headline on a recent news release from the University of Washington stating that "'sushi parasites' have increased 283-fold in past 40 years."

我特别爱吃寿司和柠汁腌鱼生，因此在看到华盛顿大学最近一篇新闻的标题是“寿司寄生虫在过去40年里增长了283倍”时，我感到非常震惊。

But after digging into the research, which came out of a marine ecology lab run by Chelsea Wood at UW's Seattle campus, I learned that the rising abundance of marine worms known as anisakids is actually less of a problem for people than it is for whales and dolphins, which are the natural hosts infected by these parasites.

但在深入钻研了这篇由华盛顿大学西雅图分校的切尔西·伍德负责的海洋生物实验室发布的研究之后，我了解到，就数量不断增加的异尖线虫而言，人类面临的风险要小于鲸鱼和海豚，而这两种动物是这些寄生虫的天然宿主。

Wood's team did what's known as a meta-analysis. They collected data from 123 papers published over the past half-century that estimated parasite abundance in various species at sites all over the world between 1967 and 2017.

伍德的团队进行了元分析。他们收集了过去50年中发表的123篇论文，这些文章估算了1967年至2017年期间全世界各种寄生虫的数量。

Their analysis, published last month in the journal Global Change Biology, found that since 1978. when less than one worm was seen in every 100 host animals on average, the prevalence of anisakid parasite infection has skyrocketed to the point that more than one worm is now typically seen in every host animal examined in 2015.

他们这篇文章于上个月发表在《全球变化生物学》期刊上，文章发现，1978年时平均100只宿主动物中只有不到1只蠕虫，而之后异尖科寄生虫感染率激增，到2015年每1只被检测的宿主动物中的蠕虫数都多于1条。

Anisakid worms grow in the guts of whales, spread to krill through the whales' poop and then move up the food chain to squid and small fish like anchovies, then to big fish like salmon, tuna, and halibut and, finally, to humans.

异尖科蠕虫生长在鲸鱼的肠道中，通过鲸鱼的粪便传播到磷虾体力，之后在食物链上攀升到鱿鱼和凤尾鱼等小鱼身上，然后再移动到鲑鱼、金枪鱼和大比目鱼等大型鱼类身上，最后传播到人类体内。

In the U.S. and most parts of Europe, fish and squid served raw must first be frozen to kill the nematodes and their larvae, which are big enough to see with the naked eye. And even if you're unlucky enough to eat live anisakid larvae in your sushi, ceviche, or gravlax, you'll probably be fine. The worms rarely survive long in the human gut to cause anisakiasis, which typically involves abdominal pain and vomiting.

在美国和欧洲大部分地区，供生食的鱼和鱿鱼必须先冷冻杀死线虫及其幼虫，而线虫及其幼虫的体型大到人的肉眼就能看到。即使你运气不好，吃到了寿司、柠汁腌鱼生或腌制三文鱼中的活的异尖线虫幼虫，你可能也没事。蠕虫极少在人类肠道中长时间存活，不会让你患上会腹痛呕吐的异尖线虫病。

The condition seems to be most common in Spain due to Spaniards fondness for raw anchovies. Experts estimate there are roughly 8.000 cases a year in Spain—that works out to about one illness for every 10.000 meals of raw fish eaten.

由于西班牙人喜欢生凤尾鱼，因此这种病在西班牙似乎最为常见。专家估计，西班牙每年大约有8000例病例，相当于每吃1万次生鱼就会产生约1个病例。

Chelsea Wood says the findings haven't put her off eating sushi. Her concern is that the rising abundance of anisakids might be harming the dolphins and whales that these parasites evolved to infect and grow inside for years. She notes that there are millions of species of parasites in the ocean, and we know very little about which ones are becoming more common. The epidemiology of the oceans is still in its infancy.

切尔西·伍德表示，研究结果并未让她对寿司失去兴趣。她担心的是，异尖线虫数量日益增加能会伤害海豚和鲸鱼，这些寄生虫经过进化会感染它们，并在其体内生长多年。她指出，海洋中有数百万种寄生虫，我们对哪些寄生虫会越来越普遍知之甚少。海洋流行病学的研究尚处于初级阶段。

Thanks for listening for Scientific American's 60-second Science. I'm Wayt Gibbs.

谢谢大家收听科学美国人——60秒科学。我是维特·吉布斯。