原文：
A modern epidemic
The first indication that something was not quiet,right with Matteo came when he was 1 month old:oozing skin rash on his face.Over the next few months it got so bad that his skin lesions weren’t healing properly .”Instead of oohing and aahing over my baby,people were disgusted”,says his mom,Cristina.At 5 months,doctors ran some tests and found that Mateo was among the 6 to 8 percent of children under the age of 3 with an allergy to food-in this case,breast milk.His mother put him on soy milk,but after a few months the skin rashes returned,and Meatteo began vomiting.His doctors put him on a predigested chemical milk made from amino acids.Now 2 and a half,Matteo is allergic to tomatoes,many vegetables and can’t even touch milk.Doctors haven’t made any promises,but when Matteo turns 5 they plan to administrer a controlled test of his allergic response to milk and other substances.They are hoping he simply outgrows his allergies.
Implausible as it seems,Matteo’s condition is at the cutting edge of modern pediatric medicine,right up there with hay fever.If a popular magazine had run a children’s health issue a hundred years ago,the first article might have been about diphtheria or cholera-external threats that the West has largely conquered by antibiotics and sanitation.Instead we are examining allergies,a self-generated danger,the result of an immune system out of sync with its surroundings.It’s a threat that may in part be an unintended consequence of our triumph over the infectious scourges of the past.And the urgency is growing .All allergies seem to be on the rise,in fact,but “it’s not just that more kids have allergies”,says Dr.Marc,director of allergy and immunology at hospital.The severity of those allergies has also increased.
An allergy is an overreaction by the immune system to a foreign substance.According to the Food Allergy ,almost any food can trigger an allergy,although eight categories account for 90 percent of all reactions:milk,eggs, peanuts(technically,a legume),tree nuts,fin fish,shellfish,soy and wheat .For reasons not fully understood ,in some people these otherwise harmless substances provoke the same reactions by which the body attempts to rid itself of dangerous pathogens.These may include sneezing,vomiting and the all-purpose localized immune-system arousal known as inflammation .The lungs may affected;allergies are a leading trigger for asthma attacks.In extreme cases,the reaction involves virtually all organ systems and proceed to anaphylaxis ,a dramatic drop in blood pressure accompanied by extreme respiratory distress that may be fatal without prompt treatment.
What can underlie such a self-destructive reaction?An infant who grows violently ill in the presence of as little as one hundredth of a peanut almost surely has some sort of genetic predisposition.Indeed,if one parent has an allergy ,chances are one in three that the child will be allergic,according to the Asthma and Allergy Foundation of America,If both parents have allergies,the odds rise to 70 percent.But the children aren’t necessarily allergic to the same things as the parents-strongly suggesting that some other factors must be at work as well.And genetics cannot explain the rapid rise in allergies over the past few years or for that matter,centuries.
So something must have changed in the environment.One obvious place to look is air pollution.Studies by Dr Saxon,chief of a clinical immunology at UCLA,and his colleague David,have found a strong correlation between pollutants-diesel exhaust and cigarette smoke-and the development of allergies.Researchers don’t believe pollution is the whole story,though;allergies have continued to climb even as smoking and air-pollution rates have fallen.But industrialization has also brought about declines in infectious diseases and close exposure to farm animals.The “hygiene hypothesis” holds that these trends have contributed to the rise in allergies.The human immune system,which evolved in a natural environment teeming with hostile bacteria and parasites,finds itself uncomfortably idle in the antiseptic confines of the modern suburb,and failing to mature properly takes out its frustration on harmless peanuts and shrimp.Numerous studies have lent support to this general notion.But although many researchers accept the hygiene hypothesis in outline,the emerging picture is of a complicated relationship,where does and timing of exposure play important but still uncertain roles,say Dr Scott .
So the hygiene hypothesis has yet to generate any concrete prescriptions.The eventual hope is for a way to artificially stimulate the immune system to reduce allergy risk without having all these diseases .Meanwhile,though,researchers are developing new drug therapies that go beyond epinephrine (for emergency treatment of anaphylaxis) and the growing array over-the-counter antihistamines(Histamine is a key substance in the cascade of biochemical events that constitute an allergic reaction).Newer drugs ,like Singulair in the chain.
Pediatricians have also begun taking allergies more seriously.One key bit of advice to mothers is to breast-feed infants exclusively for six months.Delaying children’s exposure to novel foods in this way is the hallmark for food-allergy prevention,says the American Academy of Pediatrics.once an allergy has been diagnosed,the only thing to do is draw a cordon sanitaire around the child .Susan is allergic to milk products,eggs,fish,nuts and mustard,goes so far as to check out school art supplies;a fourth-grade teacher once mentioned adding eggs to tempera paint for a better texture.Thanks to her vigilance ,her home-cooked and prefrozen meals and New York’s ubiquitous fruit and vegetable markets,David is a healthy,normal boy,an avid skier and alive
翻译：
现代流行病
马特奥1个月大的时候，第一个迹象表明他有点不安静：脸上渗出了皮疹。在接下来的几个月里，情况变得非常糟糕，以至于他的皮损无法正常愈合。他的妈妈克里斯蒂娜说：“人们不是为我的宝宝流口水，而是感到恶心。”，医生们做了一些检查，发现在3岁以下的儿童中，有6%到8%的人对食物过敏，这就是母乳。他的母亲给他喝豆浆，但几个月后皮疹复发，Meatteo开始呕吐。医生给他喝了一种由氨基酸制成的简化化学牛奶。现在是2.5，马特奥对西红柿、许多蔬菜过敏，甚至不能接触牛奶。医生们还没有做出任何承诺，但当马特奥满5岁时，他们计划对他对牛奶和其他物质的过敏反应进行一项对照试验。他们希望他能完全摆脱过敏。
令人难以置信的是，马特奥的病情正处于现代儿科医学的前沿，正处于花粉热时期。如果说一百年前有一本流行的杂志刊登了一期儿童健康杂志，第一篇文章可能是关于白喉或霍乱的外部威胁，西方主要是通过抗生素和卫生设施来战胜这些威胁，而我们正在研究过敏，一种自我产生的危险，免疫系统与周围环境不同步的结果。这是一种威胁，部分原因可能是我们战胜了过去的传染病带来的意外后果。而且这种威胁的紧迫性正在增加。事实上，所有的过敏似乎都在增加，但“不仅仅是更多的孩子有过敏症”，过敏和医院的免疫学。过敏的严重程度也增加了。
过敏症是免疫系统对外来物质的过度反应。根据食物过敏症，几乎任何食物都会引发过敏症，尽管8种食物占所有反应的90%：牛奶、鸡蛋、花生（从技术上讲，是豆科植物）、坚果、鱼翅、贝类、大豆和小麦。由于不完全了解的原因，在一些人中其他无害的物质也会引起同样的反应，身体试图摆脱危险的病原体。这些反应可能包括打喷嚏、呕吐和被称为炎症的通用局部免疫系统唤醒。肺部可能受到影响；过敏是哮喘发作的主要诱因。在极端情况下，该反应几乎涉及所有的器官系统，并进行过敏反应，血压急剧下降伴随着极度呼吸窘迫，如果不及时治疗，可能是致命的。
这种自我毁灭性的反应有什么根据？如果一个婴儿在只有百分之一花生的情况下严重生病，几乎可以肯定他有某种遗传倾向。事实上，根据美国哮喘和过敏症基金会的数据，如果父母双方都有过敏症，那么孩子过敏的几率是三分之一但是，孩子们不一定对父母的同样东西过敏，强烈地暗示其他一些因素也一定在起作用。遗传学也不能解释过去几年或几个世纪里过敏的快速增长。
所以环境一定发生了变化。一个显而易见的地方就是空气污染。加州大学洛杉矶分校临床免疫学主任萨克森博士和他的同事大卫的研究，已经发现污染物柴油废气和香烟烟雾与过敏症的发展有很强的相关性。尽管研究人员不认为污染是全部；尽管吸烟和空气污染率已经下降，但过敏症仍在继续攀升。但是工业化也导致了传染病和近距离接触农场动物。“卫生假说”认为这些趋势导致了过敏的增加。人类免疫系统是在充满有害细菌和寄生虫的自然环境中进化而来的，但在现代郊区的消毒环境中却令人不安地无所事事，如果没有适当的成熟，它就会对无害的花生和虾产生挫败感。许多研究都支持这一普遍观点。但是，尽管许多研究者大体上接受了卫生假说，但新出现的情况是一种复杂的关系，在这种关系中，暴露的时间和程度起着重要但仍然不确定的作用，比如斯科特医生。
因此，卫生假说尚未产生任何具体的处方。最终的希望是找到一种方法，在没有所有这些疾病的情况下，人为地刺激免疫系统，以降低过敏风险，研究人员正在开发新的药物治疗方法，包括肾上腺素（用于过敏反应的紧急治疗）和越来越多的非处方抗组胺药物（Histamine是构成过敏反应的生化事件级联中的关键物质）
儿科医生也开始更认真地对待过敏症。给母亲们的一个关键建议是用母乳喂养婴儿6个月。美国儿科院说，用这种方法推迟儿童接触新食物是预防食物过敏症的标志。一旦诊断出过敏症，唯一要做的就是在孩子周围画一条警戒线。苏珊对奶制品、鸡蛋、鱼、坚果和芥末过敏，甚至检查学校的艺术用品；一位四年级的老师曾经提到在蛋彩画中加入鸡蛋以获得更好的质感。多亏了她的警惕，她的家常菜和预冻食品以及纽约随处可见的水果和蔬菜市场，大卫是一个健康，正常的男孩，一个滑雪爱好者和活着的