Woman’s brain worm infection confirmed after eggs grow tails in lab test

实验室检测发现虫卵长出“尾巴”，女子脑部寄生虫感染获证实

Out of nowhere, a woman’s right arm and leg started shaking uncontrollably. In the moments leading up to the experience, she seemed well; she had no headache, confusion, or weakness. But for about a minute, half of her body juddered. The woman, a rice farmer in the Philippines, headed to the emergency department. There, doctors gave her a physical exam and found nothing out of the ordinary. Then they took a look at her brain. Magnetic resonance imaging revealed a bright cluster of nodules surrounded by fluid in her left frontal lobe. The doctors had an immediate guess as to what they were: worm eggs.

一名女子毫无征兆地出现了右侧肢体不受控制的抽搐。在发作前，她看起来一切正常，没有头痛、意识模糊或虚弱感。但大约持续了一分钟，她半边身体都在剧烈抖动。这名来自菲律宾的水稻农户随即前往急诊科就诊。医生为她进行了体检，未发现异常。随后，医生对她的脑部进行了检查。磁共振成像（MRI）显示，她的左额叶有一个被液体包围的明亮结节簇。医生立刻推测这些结节是虫卵。

In a case report published in the latest issue of the New England Journal of Medicine, doctors write that they suspected the woman had neuroschistosomiasis, an uncommon complication of an infection with a Schistosoma parasitic worm, aka a blood fluke. In the Philippines, the most common fluke is S. japonicum. It’s also found in China and part of Indonesia; despite its name, it has been eliminated from Japan.

在《新英格兰医学杂志》最新一期发表的病例报告中，医生写道，他们怀疑该女子患有神经型血吸虫病，这是感染血吸虫（又称吸血虫）后一种罕见的并发症。在菲律宾，最常见的血吸虫是日本血吸虫（S. japonicum）。这种寄生虫也存在于中国和印度尼西亚的部分地区；尽管名字叫“日本”血吸虫，但它在日本已被根除。

S. japonicum, like its relatives, has a diabolical life cycle, which starts with its eggs being shed in the urine or feces of various animals, including humans. When conditions are right, the eggs hatch into a free-swimming larval form. These seek out specific types of aquatic snails, which they bore into and inhabit to go through two life stages. Late-stage larvae then burst out, grow a forked tail, and swim to find an animal host. These tailed larvae, called cercariae, have the ability to tunnel through intact skin and take a trip through the vascular system—visiting the lungs, heart, and then liver, where they develop into adults.

日本血吸虫与其近亲一样，拥有极其复杂的生命周期。其生命周期始于虫卵随人类或其他动物的尿液或粪便排出。在适宜的条件下，虫卵孵化成自由游动的幼虫。这些幼虫会寻找特定的水生螺类，钻入其中并寄生，经历两个发育阶段。后期幼虫破壳而出，长出分叉的尾巴，游动寻找动物宿主。这些带尾的幼虫被称为“尾蚴”，它们能够穿透完整的皮肤，进入血管系统，经过肺部、心脏，最终到达肝脏并发育为成虫。

The adult male and female worms live paired together with the slender female worm tucked into a groove within the thicker male. Adult worms typically move to large blood vessels in the abdomen connecting the liver to the intestines. From there, the cuddly couples spew out eggs that make their way into feces and urine. Adult worms often go undetected in blood vessels, producing no noticeable symptoms, allowing the infection to become chronic. It’s the eggs that typically cause problems and give the worms’ presence away. They can spur inflammation, fibrosis, and organ-specific complications.

雌雄成虫通常成对生活，纤细的雌虫蜷缩在较粗的雄虫腹沟内。成虫通常会移动到连接肝脏和肠道的腹部大血管中。在那里，这对“伴侣”会产下虫卵，虫卵随粪便和尿液排出体外。成虫在血管中往往难以被察觉，不会产生明显的症状，从而使感染演变为慢性。通常是虫卵引发了问题，并暴露了寄生虫的存在。它们会诱发炎症、纤维化以及特定器官的并发症。

On rare occasions, S. japonicum eggs reach the central nervous system and cause problems. It’s not entirely clear how this happens; medical experts speculate that it may happen when either the adults or eggs get diverted into an unusual place, possibly due to a heavy infestation or vascular damage. However it happens, when eggs get lodged in the brain, they’re often linked to seizures or specific neurological problems. The possibility of S. japonicum eggs in the woman’s brain seemed like it could explain her abrupt seizure, so her doctors began diagnostic tests.

在极少数情况下，日本血吸虫卵会进入中枢神经系统并引发问题。其具体机制尚不完全明确；医学专家推测，这可能是由于寄生虫感染严重或血管受损，导致成虫或虫卵被带到了异常部位。无论如何，当虫卵滞留在脑部时，通常会引发癫痫或特定的神经系统问题。该女子脑部存在日本血吸虫卵的可能性似乎可以解释她突发的癫痫，因此医生开始了诊断测试。

The woman’s doctors first turned to an old-school lab test called the circumoval precipitin test, which was developed in the 1950s. In this test, doctors obtain a reference sample of S. japonicum eggs and flood them with a patient’s serum. If the patient has an infection, their serum will contain antibodies that can target the egg. In this event, the antibodies can grab onto molecules dangling off the outside of the egg as well as molecules secreted by the egg. In the test, this leads to a tail-like structure of bound antibodies forming on the outside of the egg.

医务人员首先采用了20世纪50年代开发的一种传统实验室检测方法——环卵沉淀试验（COPT）。在该测试中，医生获取日本血吸虫卵的参考样本，并将其浸入患者的血清中。如果患者受到感染，其血清中会含有针对虫卵的抗体。在这种情况下，抗体会附着在虫卵表面的分子以及虫卵分泌的分子上。在测试中，这会导致虫卵外部形成一种由结合抗体构成的“尾状”结构。

This test doesn’t always work, but in the woman’s case, it produced a clear result: test eggs grew weird tails, indicating an S. japonicum infection. Another test also found a lot of S. japonicum eggs in the woman’s stool: 190 eggs per gram of feces, to be precise. Together with the MRI result suggesting the presence of eggs, they diagnosed her with cerebral schistosomiasis that caused a focal seizure. The doctors prescribed her an anti-parasitic drug, an anti-inflammatory drug, and an anti-seizure medication. Three months later, the woman told doctors she had no additional seizures. A follow-up MRI showed the worm eggs were gone.

虽然该测试并非总是有效，但在该女子的病例中，结果非常明确：测试用的虫卵长出了奇怪的“尾巴”，表明存在日本血吸虫感染。另一项检查也在该女子的粪便中发现了大量日本血吸虫卵：确切地说是每克粪便中含有190个虫卵。结合MRI显示存在虫卵的结果，医生诊断她患有导致局灶性癫痫的脑血吸虫病。医生为她开了抗寄生虫药、抗炎药和抗癫痫药物。三个月后，该女子告诉医生她没有再发生癫痫。随后的MRI复查显示，脑部的虫卵已经消失。