暴增的寄生虫，威胁着我们也威胁着海豚
在三文鱼片中的异尖线虫。图片来源：Togabi Wikimedia
我非常爱吃寿司和柠汁腌鱼生（译者注：一种用青柠或柠汁配以辣椒腌制的生鱼片），所以当我看到华盛顿大学最近发布的一篇新闻报道以“‘寿司里的寄生虫’在过去40年里增加了283倍”为标题时，我震惊了。
这项研究来自华盛顿大学（University of Washington）切尔西·伍德（Chelsea Wood）的海洋生态实验室，仔细看过研究内容后，我了解到这种海洋寄生虫名为异尖线虫（Anisakis），它们数量的持续上涨虽然对人类饮食构成了威胁，但对鲸鱼和海豚这些会被感染的自然宿主来说则更为棘手。
伍德团队的研究是一项荟萃分析（meta-analysis），他们收集了过去半个世纪（1967年至2017年间）发表的123篇论文数据，这些论文估计了世界各地不同物种中含寄生虫的数量。
他们的分析结果显示，异尖线虫的感染患病率在50年间大幅上升——从1978年平均每100个宿主只有不到一只寄生虫，到2015年每个被测宿主身上都有超过一只寄生虫。这项研究于2020年3月发表在《全球变化生物学》（Global Change Biology）上。
异尖线虫在鲸鱼的肠道中发育成长，通过鲸鱼的粪便传染给磷虾，然后沿着食物链向上移动到鱿鱼和像凤尾鱼这样的小鱼，然后再到三文鱼、金枪鱼和大比目鱼这样的大鱼，最后到人类。
在美国和欧洲大部分地区，未加工的鱼和鱿鱼必须先冷冻起来以杀死大到肉眼可见的线虫及其幼虫。即使你不幸吃进了含有活异尖线虫幼虫的寿司、柠汁腌鱼生或腌三文鱼，你一般……[查看全文]
Waiter, What's This Worm Doing in My Sushi?
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.”
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 anisakis is actually less of a problem for people than it is for whales and dolphins, which are the natural hosts infected by these parasites.
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.
Their analysis, published last month in the journalGlobal Change Biology, found that since 1978, when less than one worm was seen in every 100 host animals on average, the prevalence of anisakis parasite infection has skyrocketed to the point that more than one worm is now typically seen in every host animal examined in 2015.
Anisakis 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.
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 anisakis larvae in your sushi, ceviche, or gravlax, you’ll probably...[full transcript]
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