印度旅行,一只芒果引发的腹泻
NEW DELHI - Accepting a just-picked mango from a stranger in Lodi Gardens and then putting it directly into my mouth - skin and all - was stupid. I admit that.
新德里——在洛迪花园从陌生人那里接过一枚刚刚采摘的芒果,然后直接把它连皮塞进嘴里,这太蠢了。我承认这一点。
But why did my first horrible case of traveler's diarrhea in India have to result from a mango? I love mangoes, and India's vast array of deliciously different mango varieties has been one of the great delights of moving here.
但我在印度的第一次严重的“旅行者腹泻”(traveler’s diarrhea,人们在外出旅行过程中由于感染了细菌、病毒、肠寄生虫等发生的腹泻——译注),为什么是一个芒果引发的呢?我爱芒果,印度富产的品种繁多的美味芒果,正是我被外派到这里工作的乐趣之一。
"You didn't even wash it?" Dr. Paul Offit, chief of infectious diseases at Children's Hospital of Philadelphia, asked me later.
“你不洗一下芒果就直接吃了吗?” 后来,美国费城儿童医院(Children’s Hospital of Philadelphia)的传染病科主任保罗·奥菲特博士(Dr. Paul Offit)这样问我。
No.
没洗。
"Even by your standards, that was really stupid," Dr. Offit said.
“即使按你的标准,那也是非常愚蠢的,”奥菲特博士说。
But what about the local yogurt I had eaten and the probiotic pills I had taken - weren't my gastrointestinal flora protecting me? Since we all carry 10 times as many bacterial cells as human ones, wasn't I for all intents and purposes already more Indian than American?
但是,我已经喝了当地土产的酸奶,并且吃了带到印度来的益生菌药片,我的胃肠道菌群不是能保护我吗?既然我们每个人身上携带的细菌在数量上十倍于自身的人体细胞,那么无论意图和目的,我的胃肠道菌群不是已经更印度化,而非美国化了吗?
"Yogurt probably won't hurt you, unless it's contaminated as well," Dr. Phyllis Kozarsky, an expert on traveler's health at the Centers for Disease Control and Prevention, said in an interview. But there is no food on the planet that will protect against an onslaught of toxic bacteria, she added.
“酸奶可能不会伤害你,除非它也被致病细菌污染了,”美国疾病控制和预防中心(Centers for Disease Control and Prevention)的旅行健康专家菲利斯·考扎斯基博士(Dr. Phyllis Kozarsky)在一次采访中如是说。但是她补充道,地球上没有任何食物能抵御致病细菌的侵袭。
Despite decades of immunological research and a recent surge of interest in the bacterial garden of the human gut, diarrhea remains the most unpredictable travel-related illness. There is a grim acceptance among Western expatriates and visitors here that they will be felled by it - often on multiple occasions.
尽管经过了几十年的免疫学研究和最近风靡的对人体肠道细菌群落的研究,腹泻仍然是最防不胜防的游客疾病。在印度的西方外籍人士和游客,都无可奈何地接受了一个严峻现实:他们必将遭遇腹泻,并且通常是多次腹泻。
And there is a host of myths surrounding traveler's diarrhea, many of which I have cheerfully perpetuated to family and friends. (Well, mostly to my wife.) There are also intriguing mysteries about how natives gain immunity to the food- and waterborne bacteria that prove so toxic to non-natives.
许多传说缭绕着旅行者腹泻,我兴高采烈地把其中不少内容传授给亲友。(好吧,主要是传授给我的妻子。)坊间也流传着许多令人着迷的传说,比如印度当地人如何获得了外国人望尘莫及的免疫力,能抵御食源性和水源性的致病菌。
I have lived in India for four months, and I have been in gastrointestinal distress five times - roughly once a month. Part of the problem is that Indians are a very hospitable people. Almost everywhere I go, someone offers me food and drink, forcing me to quickly weigh the chance of contamination against the likelihood that a refusal would cause offense.
我已经在印度住了四个月,我经历的胃肠道不适有五次之多——大致是一个月一次。部分原因是印度人非常好客。几乎无论我去哪里,都有人好吃好喝招待着我,迫使我不得不赶紧在心头盘算究竟是冒着食物被污染的可能性吃下去,还是冒着拒绝好意而得罪人的风险咬紧牙关就是不吃。
Beyond this coldhearted calculus is my very real desire to connect with people. The mango in question was given to me by a woman with such obvious good will that I found refusing her difficult.
在看似冷漠的权衡背后,是我真心渴望与当地人交流。引发腹泻的芒果就是一个女人客客气气送到我嘴边的,我感到盛情难却。
I bit into the mango, putting my mouth on the peel to suck out the juice and pulp. As I did this, my brain engaged. A bird might have covered the mango in droppings. The mango might have fallen on the ground. The woman handing it to me might have been covered in toxic E. coli (more than 600 million people in India have no routine access to bathrooms).
我咬了一口芒果,把我的嘴对着扒开的那部分,吸出果汁和果肉。当我吃的时候,我的大脑转个不停。一只小鸟也许曾在芒果上逗留。芒果可能曾落在地上。递给我芒果的女人可能自身携带着致病的有毒大肠杆菌(在印度,六亿多人都没有常规的如厕条件)。
Within hours, my stomach was in an uproar and I was seized with a fever. I knew I was in trouble because my first three cases of traveler's diarrhea had been mild enough that I managed to get through them without taking any medicines, something I considered a personal triumph mostly because it allowed me to compare myself favorably with my wife.
没过几个钟头,我的胃就开始翻江倒海,开始发烧。我知道自己麻烦大了,因为我前三次患上的旅行者腹泻都不厉害,没有服用任何药物就扛过去了,那会儿我还为此颇为自得,主要是因为这令我显得比妻子略胜一筹。
Indeed, my wife joined me for the first week of my stay here before returning temporarily to the United States, and within four days she became terribly ill. I freely dispensed what turned out to be terrible advice, suggesting in the early hours of her illness that she avoid taking one of the antibiotic pills that we had brought for just such an eventuality.
确实如此,我的妻子和我一起来到印度,待了一个星期之后,她暂时返回美国,回美国不到四天,她就病倒了。我随随便便给她的建议后来被证明是糟糕透顶的,我建议她在发病的最初几个小时,避免服用抗生素药,虽然我们手头就有备用的抗生素应对可能会出现的旅行者腹泻。
My advice sprang from the mistaken belief that the good bacteria in her gut had a fighting chance against the bad bacteria. "Honey, taking an antibiotic is like carpet-bombing a battlefield," I told her in confident tones. "You kill off all the good guys as well as the bad guys. Let's see if the good guys rally first."
我的建议是源于错误的观念,我认为她肠道菌群中的益生菌有可能击溃致病菌。 “亲爱的,服用抗生素如同地毯式轰炸战场,”我充满自信地告诉她:“你会把好人和坏人一古脑统统杀死。让我们先等等,看这帮好人能不能发威。”
They did not. As it turns out, the fight against toxic bacteria is largely waged by the body's immune system, not the sweet-tempered millions found in a spoonful of yogurt.
它们不能。事实证明,有毒细菌的击溃主要是靠人体的免疫系统,而不是靠每匙酸奶中数以百万计、脾气温吞的益生菌。
"An immune response is a much more powerful agent against these bacteria than is trying to rearrange things within your intestinal flora," Dr. Offit said. The wait, of course, simply ensured that the toxic bacteria were allowed to thrive and make her very sick, delaying her return home.
“与试图重新调理你身体的肠道菌群相比,免疫反应更能强有力地击溃致病菌,”奥菲特博士说。自然了,等待的这段时间只会让有毒细菌趁机发展壮大,使她病得更重,延迟了她返家的时间。
Oops.
哎呀呀。
That Indians are less likely to be sickened by the foods that felled my wife and me results less from their different intestinal flora than from years of hard-won immunologic experience, said Dr. David Relman, a microbiologist at Stanford University School of Medicine.
美国斯坦福大学医学院(Stanford University School of Medicine)的微生物学家大卫·雷尔曼博士(Dr. David Relman)说,导致我和我妻子生病的食物,印度本地人吃了之所以没事,主要是因为他们的免疫系统久经沙场经历了来之不易的磨练,而不是因为他们的肠道菌群与我们的不同。
"Although it may appear that a lot of adults don't seem to develop diarrheal disease, they probably had a fair bit of it as kids, and it was through those episodes that they got immunized," Dr. Relman said.
“虽然印度的很多成年人看起来不容易腹泻,但是他们在小时候可能拉了很多次肚子,正是通过幼年的磨练,使他们获得了免疫力,”雷尔曼博士说。
But without experience fighting these new invaders, my wife's immune system had little chance of preventing her illness. That is why quickly taking antibiotics is so crucial. They are often miraculous cures, because 80 percent to 90 percent of traveler's diarrhea cases are caused by bacteria, Dr. Kozarsky said.
但是,我们可从未实战抵御过这些新的入侵者,所以我妻子的免疫系统就几乎不可能防御腹泻。这就是为什么迅速服用抗生素是如此重要。考扎斯基博士说,抗生素往往是灵丹妙药,因为80%到90%的旅行者腹泻都是由细菌引起的。
Imodium, also known as loperamide, is effective too. Again, this was news to me. Initially, my wife decided against taking Imodium because she thought doing so would lengthen the duration of illness. I concurred. Wrong again.
同样有效的是易蒙停(Imodium),或称洛哌丁胺(loperamide)。而这一点我以前也不知道。最初,我妻子决定不服用易蒙停,因为她认为易蒙停会延长病程。我同意了。我又错了。
There is no evidence that Imodium lengthens the illness, Dr. Kozarsky said. Instead, it simply ameliorates the illness's highly disruptive symptoms - a significant benefit when the short trip to the bathroom seems like a marathon.
考扎斯基博士说,没有证据表明易蒙停会延长病程。相反,它只会减轻翻江倒海的腹泻症状——在你病体虚弱不堪的时候,易蒙停的一个明显好处就是减少了你上厕所的次数。
Still, there are risks associated with aggressive treatment of traveler's diarrhea. Antibiotic therapy can increase a patient's vulnerability to other toxic bacteria, Dr. Relman said. All the good bacteria that normally inhabit the human gut - bacteria that get decimated with antibiotics - somewhat inhibit toxic microbes from getting a foothold or flourishing, even if they cannot fight off a full-scale assault.
不过,旅行者腹泻的过度积极治疗也会有风险。雷尔曼说,抗生素治疗使患者更容易感染上其它的有毒细菌。这是因为抗生素把益生菌杀灭了,人体肠道菌群中正常的益生菌即使不能抵御毒性细菌的全面猛攻,也能在一定程度上阻止毒性细菌在肠道中安营扎寨、繁荣昌盛。
"If you take an antibiotic and then get on a plane to India, you're much more likely to develop a serious infection," Dr. Relman said.
“如果你先服用抗生素预防,然后登上飞机去印度,那么你就更有可能患上严重的感染性疾病,”雷尔曼博士说。
Without those bacteria, the body may be more susceptible not only to other bacterial infections but even to viral ones like the flu, said Dr. Susan M. Huse of the Marine Biological Laboratory in Woods Hole, Mass.
美国马萨诸塞州伍兹霍尔市海洋生物实验室(Marine Biological Laboratory)的苏珊·M.休斯博士(Dr. Susan M. Huse)说,如果人体缺失了这些益生菌,那么不仅更容易遭遇其它细菌性感染,而且也更容易患上像流感这样的病毒性感染。
Studies also have suggested that the obsessive cleanliness in the West and overuse of antibiotics may be creating a generation whose immune systems, perhaps too protected from attack in childhood, are now constantly on overdrive, resulting in far more asthma and allergies. My 7-year-old son has had both problems, and while I am hopeful that the seemingly plentiful array of different bacteria here may help him, I certainly do not wish for him to get horribly sick in the meantime.
研究还表明,在西方发达国家,过度讲究干净和滥用抗生素的环境下成长起来的一代人,他们的免疫系统因为在幼儿时缺乏磨练,所以长大后就不断产生过激反应,导致哮喘和过敏症的发病率猛增。我七岁的儿子就患有上述这两种病,我虽然希望印度看似琳琅满目的细菌种类能驯化他的免疫系统,但我当然不希望他在此期间得重病。
Indeed, repeated cases of traveler's diarrhea can damage the gut's ability to absorb nutrients and cause stunted growth in children, Dr. Relman said. Some studies suggest gut bacteria could even play a role in the development of obesity.
雷尔曼博士说,多次反复发作旅行者腹泻可能会损坏肠道的营养吸收能力,延迟儿童的生长发育。一些研究表明,肠道细菌甚至可能导致发胖。
If there is a benefit from exposure to bad bacteria, it most likely occurs in infancy, when immune systems are still developing, said Michael Fischbach, a microbiologist at the University of California, San Francisco. My son is probably too old for new bacterial exposures to retrain his immune responses.
美国加州大学旧金山分校(University of California, San Francisco)的微生物学家迈克尔·菲施巴赫(Michael Fischbach)说,如果接触坏细菌对人体有好处,这好处最有可能发生在婴儿期,因为这时免疫系统还在发育之中。我的儿子可能已经年岁太大了,没法再通过接触新的细菌来重新调教他的免疫反应。
To ward off diarrhea, Dr. Fischbach endorsed eating yogurt and other fermented foods, particularly after using antibiotics, although he said there is little evidence proving the effectiveness of this strategy.
菲施巴赫博士认为吃酸奶以及其它的发酵食品,尤其是在服用抗生素之后多吃这些食物,能预防腹泻,不过他表示目前并没有多少证据证明这种做法的有效性。
Dr. Kozarsky recommended daily doses of Pepto-Bismol, which can reduce the risks of contracting traveler's diarrhea during brief stays. Pepto-Bismol is not recommended for long periods, she said. Indeed, some antacid therapies can increase vulnerability to traveler's diarrhea.
考扎斯基则建议在短期旅行时每日服用一定剂量的碱式水杨酸铋(Pepto-Bismol),这能够减少患旅行者腹泻的风险。但她不建议长期服用该药。事实上,一些抗酸剂药物可以增加患旅行者腹泻的风险。
She recommended that travelers limit meals to foods that resist bacteria or those that have been well cooked. "If you eat things that are still steaming, the bacteria will be killed," Dr. Kozarsky said.
她建议外出旅行时只吃抗菌或已彻底煮熟的食物。“如果你吃的食物是热气腾腾的,那么细菌就已经被消灭光了,” 考扎斯基说。
Since we live here, we cannot abandon fresh fruits and vegetables. Instead, we soak them in diluted bleach - including our mangoes. Because gut bacteria are now suspected by scientists of playing roles not only in keeping my weight down but also in protecting against a variety of chronic diseases, like autoimmune disorders and diabetes, I will continue to try to get through mild bouts of diarrhea without resorting to medication.
既然我们在印度生活,我们就不能放弃吃新鲜的水果和蔬菜。吃之前,我们先用稀释的漂白剂浸泡果蔬——包括芒果在内。由于科学家们现在认为肠道细菌不仅能有助于体重下降,而且能有助于预防各种慢性疾病,如自身免疫性疾病和糖尿病,所以我仍然会按老办法来,碰到轻度腹泻时尽量不吃药。
But if I develop a fever or really suffer, I plan immediately to take ciprofloxacin, a powerful antibiotic that is available over the counter in India.
但是,如果我开始发烧或感觉痛苦难耐,就会立即服用环丙沙星,这种强效抗生素在印度是非处方药。
My repeated bouts of serious illness meant that I was no more robust or prepared for India than my wife, a tough blow to my ego. I have been sick more days than she. Living here will make me less vulnerable over time, but I no longer strive to become as resistant to infections as my Indian neighbors.
在印度,我反反复复发生严重腹泻,表明在体质或适应性上,我居然比不上妻子,这沉重地打击了我的自尊心。我生病的天数比她生病的天数更多。住在这里,随着时间的推移,我将越来越能抵御感染,但我并不想在这方面赶超我的印度邻居。
To achieve that, "you would suffer a variety of illnesses," Dr. Offit said. "And under the assumption that suffering is bad, I wouldn't recommend it."
为了达到印度本地人抵御感染的能力,“你必须经受各种感染性疾病的折磨,”奥菲特说。“我估计受折磨终归不是好事,所以这个方法我不推荐你使用。”