Episode Details

Somewhere on a farm in Iowa in 2010, a hen lays an egg. In just a few short weeks, this egg will be part of a massive infection event: thousands of people will fall ill, millions of eggs will be recalled, and several egg industry titans will ultimately land in jail, all thanks to a microscopic but mighty bacterium.2010年，在爱荷华州的一座农场里，一只母鸡产下了一枚鸡蛋。仅仅几个星期后，这枚鸡蛋将成为一场大规模感染事件的一部分：成千上万的人会生病，数百万枚鸡蛋将被召回，而几位蛋业巨头最终会锒铛入狱，而这一切都源于一种微小却强大的细菌。

Salmonella infects millions worldwide each year, causing fever, stomach cramps, and diarrhea. And these effects can be extreme: Salmonella is the leading cause of hospitalizations and deaths from food poisoning.↳每年，全世界有数百万人感染沙门氏菌，导致发烧、胃痉挛和腹泻。这些影响可能非常严重：沙门氏菌是食物中毒导致住院和死亡的主要原因。

So, let’s follow this microbe to find out how it makes so many people sick.那么，让我们跟随这种微生物，看看它是如何让如此多人患病的。

We begin in the chicken's digestive tract, a major source of all Salmonella infections. In chickens, Salmonella bacteria often go undetected, allowing them to spread to eggs either through the developing yolk or by passing through feces, which can then contaminate shells. Under unhygienic farming conditions, this Salmonella-laden feces may also infect or contaminate other animals and crops, causing various food-linked outbreaks. Meanwhile, chicken meat can be exposed to intestinal Salmonella during processing.我们从鸡的消化道开始，它是所有沙门氏菌感染的主要来源。在鸡体内，沙门氏菌常常不易被察觉，它们可能通过正在发育的蛋黄传播到鸡蛋中，或通过粪便排出并污染蛋壳。在不卫生的养殖条件下，这些含有沙门氏菌的粪便还可能感染或污染其他动物和农作物，导致各种与食物相关的疫情。同时，在加工过程中，鸡肉也可能接触到肠道中的沙门氏菌。

On its journey from farm to plate, the microbe can survive extreme cold, wet, and dry conditions. However, once it moves into a human body, Salmonella reveals its true talents for survival. The first hurdle is the stomach. Here, most bacterial invaders are killed off by stomach acid. But Salmonella cells can detect acidic conditions, which triggers the production of acid shock proteins. These molecules shield the bacteria from damage just long enough for it to pass into the intestines.↳在从农场到餐桌的旅途中，这种微生物能在极端的寒冷、潮湿和干燥环境中生存。然而，一旦进入人体，沙门氏菌便展现出它真正的生存本领。第一道关卡是胃。在这里，大多数细菌入侵者都会被胃酸消灭。但沙门氏菌能感知酸性环境，从而触发酸冲击蛋白的产生。这些分子保护细菌免受伤害，正好能支撑它们进入肠道。

Salmonella then faces the next gauntlet, as intestinal cells swiftly unleash microbe-destroying immune cells. But once again, the bacteria detect these changes with inbuilt sensors. And embedded within Salmonella’s genome are pathogenicity islands, clusters of adaptive genes that launch the next phase of attack. They signal the construction of a specialized system that resembles a needle and syringe. Within seconds, it injects molecules called effector proteins into the intestinal cells, causing them to change their structure and swallow up the Salmonella. Once inside, Salmonella can then exploit the cell machinery to replicate