What Actually Happens When a Person Is Infected With the Ebola Virus

感染埃博拉病毒之后
 
(选自《英语世界》2014年第11期)

译/修文乔
 
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The worst outbreak of Ebola virus in history – happening now in West Africa– has claimed about 4500 lives, according to the latest count from the World Health Organization. The deaths occurred in Sierra Leone, Liberia, Guinea and Nigeria. 
史上最严重的埃博拉病毒疫情在西非爆发。根据世界卫生组织最新统计数据,此次疫情已经夺去大约 4500人的生命。死者多来自塞拉利昂、利比亚、几内亚和尼日利亚。
 
[2] “This outbreak is moving faster than our efforts to control it,” Margaret Chan, chief of the World Health Organization, said at a meeting, as reported by Reuters. 
〔2〕据路透社报道,世卫组织总干事陈冯富珍在一次会议上表示:“此次疫情的扩散速度远远超出了我们的控制能力。”
 
[3] The Zaire strain of the Ebola virus that’s involved in the current outbreak has had a fatality rate in the past of up to 90 percent. However, the fatality rate of the current outbreak is lower. That’s because “90 percent is when you receive absolutely no medical care,” said Dr. Nahid Bhadelia, M.D., the associate hospital epidemiologist at Boston Medical Center and director of Infection Control at Boston University’s National Emerging Infectious Disease Laboratories.
〔3〕此次爆发的扎伊尔型埃博拉病毒的死亡率曾高达90%,但此次疫情的死亡率较低。波士顿医疗中心医院流行病学副研究员、波士顿大学国家突发急性传染病实验室传染病控制中心主任、医学博士纳黑德•巴迪利亚认为:“90%死亡率的原因在于当地完全不具备医疗条件。”
 
[4] “Right now you’re seeing with supportive care, there’s a 60 percent mortality in the field,” she told HuffPost. 
〔4〕她告诉《赫芬顿邮报》的记者:“目前,在接受有效治疗的情况下,埃博拉病毒的死亡率是60%。”
 
[5] But how exactly does the virus work to provoke such extreme symptoms – Ebola is notorious for causing, in some cases, bleeding from the eyes and ears – and cause death? Bhadelia explained why the body has such a hard time fighting off the deadly virus: 
〔5〕埃博拉病毒有时会引发患者眼睛和耳朵出血,该病毒究竟如何引发如此极端的症状并导致死亡的?巴迪利亚医生解释了人体难以战胜埃博拉病毒的原因:
 
How does ebola enter the body in the first place?
埃博拉病毒如何入侵人体?
 
[6] Ebola is not known to infect people through the air – you must come into contact with the virus somehow in order to be at risk for infection, Bhadelia said. It’s transmitted through exposure to an animal that carries the virus (such as a bat or primate), through exposure to the bodily fluids of a human who is infected and symptomatic, and through exposure to items that have been contaminated with the virus. People who are “providing care for a household member ... when they’re cleaning up vomit or diarrhea, they come into contact [with the virus], and the way it’s transmitted is there’s virus in the fluids,” she said. “That virus gets into your own body through the nose, mouth and such.” 
〔6〕巴迪利亚指出,目前尚未发现埃博拉病毒通过空气传播的证据,人体必须接触病毒才有可能感染。病毒传播的途径包括:接触携带病毒的动物(如蝙蝠或灵长类动物);接触感染并出现症状者的体液;接触受到病毒污染的物体。她还称:“病人家属在清理患者呕吐或腹泻污物时可能被感染,因为病毒能够通过体液进行传播,通过鼻腔、口腔等部位进入人体。”
 
[7] Ebola can also survive outside the host for a significant period of time – as long as a couple of days –at room temperature. “That’s why infection control is such a huge part of this,” Bhadelia said. “If you have sterilization of equipment, if you have availability of disinfectant, things like IVs ... and if you’re able to clean all those environments and isolate patients effectively, the outbreak would never take a foothold.” This is why places with good infection control and medical infrastructure face absolutely no risk for outbreaks from this pathogen, she added. 
〔7〕室温条件下,埃博拉病毒还能在宿主体外存活相当一段时间,有时长达好几天。“这就是感染控制如此重要的原因,”巴迪利亚说,“如果能对设备进行消毒,如果备有碘类消毒剂……如果能够清洁感染环境,并将病人进行有效隔离,疫情绝不会如此肆虐。”她补充道,这就是为什么在感染得到较好控制和医疗基础设施健全的地区,绝不可能面临埃博拉病毒大规模入侵的风险。

What happens in the body once infection occurs?
感染病毒后,身体会发生什么变化?
 
[8] Once the Ebola virus makes its way into the body, it gets in the body’s cells and replicates itself. “Then it comes bursting out of our cells and produces this protein that wreaks havoc,” Bhadelia explained. The protein is called ebolavirus glycoprotein, and attaches to the cells on the inside of the blood vessels. This increases permeability of the blood vessels – leading to blood leaking out of the vessels. “The virus causes derangement in the body’s ability to coagulate and thicken the blood,” she said. Even people who don’t show hemorrhagic symptoms will experience this leaking of blood from the vessels – which can eventually lead to shock and, ultimately, death.
〔8〕埃博拉病毒一旦进入身体,就会入侵人体细胞,并进行自我复制。“然后细胞进行分裂,并产生造成严重破坏的蛋白质。”巴迪利亚解释。这种蛋白质称为埃博拉病毒糖蛋白,它附着于血管内侧细胞,增加血管的渗透性,导致血液渗出血管。她说:“埃博拉病毒造成人体凝血功能紊乱,增加血液黏稠度。”患者即使没有出现出血症状,也会有血液渗出血管,最终导致休克,甚至死亡。 
 
[9] The Ebola virus is also a master of evading the body’s natural defenses: It blocks the signaling to cells called neutrophils, which are white blood cells that are in charge of raising the alarm for the immune system to come and attack. In fact, Ebola will infect immune cells and travel in those cells to other parts of the body – including the liver, kidney, spleen and brain. 
〔9〕埃博拉病毒还擅长侵袭人体的天然免疫系统:它阻碍向“嗜中性粒细胞”发出信号,该细胞是白细胞的一种,负责唤醒人体免疫系统进行防御。实际上,埃博拉病毒会感染免疫细胞,并通过这些细胞迁移到人体其他部位,如肝脏、肾、脾和大脑。
 
[10] Each time one of the cells is infected with the Ebola virus and bursts, spilling out its contents, the damage and presence of the virus particles activates molecules called cytokines. In a healthy body, these cytokines are responsible for provoking an inflammatory response so that the body knows it’s being attacked. But in the case of an Ebola patient, “it’s such an overwhelming release [of cytokines], that’s what’s causing the flu-like symptoms” that are the first sign of Ebola, Bhadelia said. 
〔10〕一旦某一细胞感染埃博拉病毒并进行分裂,埃博拉病毒就会随之扩散。病毒颗粒极具破坏性,会激活一种名为“细胞因子”的分子。受到外界攻击时,健康人体中的细胞因子负责向人体发出“防御”信号。但对于埃博拉患者而言,“大量细胞因子释放出来,使病人表现出类似流感的症状”,巴迪利亚医生称,这就是感染埃博拉病毒的早期症状。
 
What do the symptoms look like?
感染埃博拉病毒的症状
 
[11] Ebola generally starts with flu-like symptoms. Though it’s known for the extreme hemorrhagic symptoms – the bleeding out of the eyes, etc. – not everyone will experience these. “In fact, only 20 percent of people will have [these extreme symptoms],” Bhadelia said. “Some people may succumb to the illness before it gets to that point, some may have minor bleeding, some may just have bleeding of the gums, or bruising.”
〔11〕埃博拉病毒的早期症状通常类似于流感。虽然它的极端症状表现为眼部等部位出血,但并非每位患者都会遇到这种情况。“实际上只有20%的感染者会出现极端出血症状,”巴迪利亚说,“有些人没等出现这种症状就已经死亡,有些可能有轻微出血的现象,有的只会出现牙龈出血或瘀伤。”
 
[12] The flu-like symptoms typically occur in the first stages of the illness, before the person gets sicker and starts to experience more severe symptoms such as vomiting, diarrhea and low blood pressure. The extreme bleeding occurs toward the end of the illness. People who die from infection with Ebola virus usually end up dying from multi-organ failure and shock. “The shock is from the bleeding – now you’re bleeding in different parts of your body, and the blood is leaking out of your blood vessels,” Bhadelia explained. “Even if [you don’t have] the hemorrhagic features, you’re still leaking blood.” 
〔12〕类似流感的症状通常在感染埃博拉病毒的早期出现,然后患者病情加重,并开始出现呕吐、腹泻、低血压等更严重的症状。重度出血症状发生在病情末期。因感染埃博拉病毒致死的患者通常死于多器官衰竭和休克。“休克是由出血引起的,病情后期患者身体多处部位出血,血液仍会从血管中渗出。”巴迪利亚解释,“即使没有流血不止的症状,也会有血液渗漏。”

How is it that some people have survived the deadly infection?
为何有些患者能够存活?
 
[13] It largely has to do with two factors. The first is the person’s health in general – his or her immune system and ability to bounce back from a viral infection. The second is the type of exposure he or she got. Recovery may be more likely if it wasn’t a severe exposure – meaning, perhaps they were exposed to someone who was only early on in the illness, and the amount of virus in the bodily fluids was not yet that high, Bhadelia said.
〔13〕存活与否在很大程度上取决于两个因素。首先是感染者自身的总体健康状况,在遭到病毒感染之后,患者免疫系统是否具有抵御和修复能力。其次是感染程度。巴迪利亚医生说,如果感染不太严重,比如与刚得病的患者接触,感染者体液中的病毒浓度尚不太高,那么恢复的可能性就很大。 
 
[14] In addition, what is known about Ebola is that it requires a known marker that aids in bringing the virus from the surface of the cells into the cells. Researchers have found in a laboratory setting that some people’s cell lines actually lack this marker, or it may be mutated somehow, so that the Ebola can’t get into the cells. However, Ebola research is still very much in its infancy, and knowledge about how the virus behaves is still evolving, Bhadelia said. 
〔14〕此外,研究发现,埃博拉病毒需要一个已知位点,帮助其从细胞表面深入细胞内部。研究人员在实验室发现,有些人的细胞系没有这种位点,或者位点发生变异,因此埃博拉病毒无法进入细胞。然而,巴迪利亚表示,对于埃博拉的研究尚处于初级阶段,关于埃博拉病毒的传染情况有待进一步探索。
 
[15] Still, findings like these do pave the way for potential treatments. Right now, she said, research is being done to develop treatments that work in several different ways. One of the ways is to block the virus from replicating itself once it’s inside the cell. “It basically provides a full stop and doesn’t let the virus copy its genetic material over and over again to create the new viruses,” Bhadelia said. Another way is to help the body’s immune system create an effective response to Ebola by exposing the immune system to an attenuated version of the virus. That way, “it can create an effective response so when the real virus comes around, the immune system doesn’t get evaded the way it does regularly.” And yet another way is to actually create antibodies specifically against the virus, so “you’re giving the immune system a boost from the outside,” she said. ■
〔15〕毋庸置疑,这些研究成果为改进治疗方案奠定了基础。她说,目前的研究工作致力于通过多种途径推进治疗。其中之一是阻止病毒在细胞内进行自我复制。巴迪利亚说:“其基本原理是遏制病毒不断复制遗传物质,进行繁殖。”另一方案是让免疫系统接触稀释后的病毒,帮助人体免疫系统有效防御埃博拉。这种方法“能使免疫系统有效运作,在真病毒入侵时,免疫系统不会像原来那样完全崩溃”。第三种方案是研发出真正遏制这种病毒的抗体,如此一来“就能从外部助力免疫系统”。 □
 
(译者单位:中国石油大学外国语学院)
 

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