为什么有这么多孩子对花生过敏

Peanut allergy has become a nemesis for increasing numbers of children and parents in recent years, forcing them to maintain nut-free households and prompting many schools to ban a childhood staple, peanut butter, from the lunchroom.

近年来，花生过敏症日益威胁着孩子们的健康，这不仅迫使越来越多的家长不得不将所有坚果都清除出家庭环境，还促使不少学校将儿童时代的主食之一——花生酱请出了餐厅。

When a child is allergic to peanuts, families must closely monitor everything the child eats both in and outside the home, because accidental consumption of peanuts could prove fatal. Many airlines no longer offer peanuts for fear that an allergic passenger might inhale peanut dust and suffer a life-threatening reaction at 30,000 feet.

当一个孩子对花生过敏时，无论家里家外，他的家人都必须密切监控他塞进嘴里的任何东西，因为一不小心吃到花生就很可能有生命危险。许多航空公司的餐饮中都不再提供花生，以免对此过敏的乘客吸入花生粉末，以致在30000英尺（约9144米）的高空出现危及生命的过敏反应。

The prevalence of peanut allergy among children in the United States has risen more than threefold, to 1.4 percent in 2010 from 0.4 percent in 1997, according to a study by Food allergists at Mount Sinai Hospital in New York City. Most people with an allergy to peanuts are also allergic to one or more tree nuts, like walnuts, pecans or almonds.

纽约市西奈山医院(Mount Sinai Hospital)一名食物过敏症专科医生的研究表明，美国儿童中的花生过敏症患病率从1997年的0.4%上升到了2010年的1.4%，增加了两倍还多。大多数花生过敏症患者同时也对一或多种坚果，如核桃、美洲山核桃或杏仁等过敏。

To help protect such people from inadvertent exposure to nuts, labels on packaged foods often voluntarily state whether they were prepared in a facility that also processes nuts.

为了防止这类人不至于意外接触到坚果，袋装食品的标签往往会主动声明该食品的生产设备是否也用于处理坚果。

Some cities have nut-free bakeries that now sell products safe for allergic children, who can bring their own special, albeit expensive, cake or cupcake to a party.

一些城市设有无坚果面包店，以向过敏的孩子们销售特殊、安全（但昂贵）的蛋糕或杯子蛋糕，供他们在参加聚会时携带。

While experts doubt the necessity of some extreme measures taken to prevent indirect exposure to peanuts, the danger to someone with a peanut allergy who eats them is unquestioned.

虽然关于是否有必要采取某些极端措施来防止间接接触花生，专家们持怀疑态度，但食用含有花生成分的食物对花生过敏症患者而言无疑十分危险。

The potentially fatal reaction, called anaphylaxis, can occur with a child's first exposure to peanuts: itchiness, swelling of the tongue and throat, constriction of the airway, a precipitous drop in blood pressure, rapid heart rate, fainting, nausea and vomiting.

当儿童第一次接触到花生时，可能会发生一种具有潜在致命性的反应，称为过敏反应(anaphylaxis)，其表现为：瘙痒、舌头和咽喉肿胀、气道收缩、血压骤降、心率加快、昏厥、恶心呕吐等。

Unless the reaction is stopped by an injection of epinephrine (adrenaline), anaphylaxis can kill. In one infamous instance in 1986, Katherine Brodsky, 18, a freshman at Brown University with a known nut allergy, died after eating chili that a restaurant had thickened with peanut butter.

如不及时通过注射肾上腺素遏制该反应，过敏反应可能导致死亡。1986年，布朗大学(Brown University)发生了一起著名的惨痛案例：18岁的大一新生凯瑟琳·布罗德斯基(Katherine Brodsky)对坚果过敏，她因在餐厅食用了用花生酱加稠的咖喱而死亡。

There is no cure for nut allergies, although several preliminary studies suggest that it may be possible to temper a reaction to peanuts with immunotherapy. Like shots given for pollen allergies, the approach starts with exposure under the tongue to a minuscule amount of the offending peanut protein, followed by exposure to gradually increasing amounts under strict medical supervision.

目前尚没有办法可以彻底治愈坚果过敏，但若干初步研究表明，采用免疫疗法或可缓和患者对花生的反应。这种方法与对付花粉过敏的方法类似：患者从舌下接触微量具有刺激性的花生蛋白开始，随后在严格的医疗监督下逐步加量。

The latest study, conducted in Cambridge, England, and published in The Lancet last week, found that after six months of oral immunotherapy, up to 91 percent of children aged 7 to 16 could safely ingest about five peanuts a day, far more than they could before the treatment. About one-fifth of treated children reacted to ingested peanuts, but most reactions were mild, usually an itchy mouth. Only one child of the 99 studied had a serious reaction.

最近的一项研究在英国剑桥(Cambridge)进行，并于上周发表在《柳叶刀》杂志(The Lancet)上。该研究发现，在接受口服免疫疗法半年后，七至16岁的儿童中有91%可在一天内食用五颗左右的花生，且不会出现严重不良反应，这一安全摄取量远远超过了治疗前的水平。在接受治疗的儿童中约有五分之一在食用花生后仍会出现反应，但其大多数都非常轻微，通常只是嘴部发痒而已。在所研究的99名儿童中，只有一人出现了严重反应。

When immunotherapy works, the research suggests, the severity of the allergy is lessened, enabling an allergic person to safely ingest small amounts of the offending protein. It is not known how long protection lasts without continued immunotherapy, however, and the researchers warned that no one should try it on his own. Further study is needed before the treatment can be used clinically, probably years from now.

该研究显示，当免疫疗法起效时，过敏的严重程度有所减轻，这使过敏患者得以安全地摄取少量具有刺激性的蛋白质。目前尚不清楚在中止免疫疗法后这种保护作用还可以持续多久，但研究人员警告说，任何人都不应擅自进行此类尝试。若干年后，该疗法也许能够进入临床应用，但在此之前，还需要进一步的研究。

Meanwhile, everyone with a peanut allergy is advised to carry an EpiPen for emergency treatment.

此外，专家们建议，每一位花生过敏症患者都应随身携带EpiPen（预装肾上腺素的自动注射器），以备在必要时进行急救。

Ideally, allergists would like to prevent the development of peanut allergy in the first place. Experts had thought that one way would be to keep fetuses and breast-fed babies from exposure to peanut protein by restricting consumption by pregnant and nursing women.

在理想情况下，过敏症专科医生希望能将花生过敏扼杀在摇篮里。专家们认为，其方法之一是严格限制妊娠期和哺乳期妇女对花生食品的摄取，从而避免胎儿和母乳喂养期的婴儿接触到花生蛋白。

Various studies had suggested that early exposure to peanut protein by infants with allergic tendencies could sensitize them and lead to a serious peanut allergy. In 2000, pregnant and nursing women were advised to avoid eating peanuts, especially if allergies ran in the family. And new mothers were told not to give babies peanuts before age 3, when digestive systems are more fully developed.

为数众多不同的研究表明，具有过敏倾向的婴儿过早地接触到花生蛋白很可能会引起致敏，继而导致严重的花生过敏。2000年，专家们建议：孕妇和哺乳期妇女应避免食用花生，对于具有过敏性疾病史的家庭尤其如此。他们还告诫新妈妈们：在宝宝年满三岁，消化系统充分发育前，不要给他们吃花生。

But this advice did nothing to curb the steady climb in peanut allergies, and it was abandoned in 2008.

但这些建议丝毫未能遏制花生过敏症病例稳步攀升的趋势，因此，它们在2008年被撤销。

Today, the thinking is exactly the opposite. Instead of restricting exposure to peanut protein by unborn or nursing babies, the tiny amounts that may enter the baby's circulation when a pregnant or nursing woman eats peanuts might actually induce tolerance, not sensitization.

今天，人们对付过敏症的思路与之前的完全背道而驰。人们不再严格限制未出生或哺乳期的婴儿接触花生蛋白，相反，人们认为，当孕妇或哺乳期妇女食用花生时，进入宝宝血液循环里的微量花生蛋白将诱导免疫耐受，而不是致敏。

In a recent study of 8,205 children, 140 of whom had allergies to nuts, researchers found that children whose nonallergic mothers had the highest consumption of peanuts or tree nuts, or both, during pregnancy had the lowest risk of developing a nut allergy. The risk was most reduced among the children of mothers who ate nuts five or more times a month.

在一项涉及8205名儿童（其中140人对坚果过敏）的近期研究中，研究人员发现，自身不过敏，且在妊娠期食用花生和/或坚果量最高的母亲所生下的孩子日后发生过敏症的风险最低。在母亲每个月至少食用坚果五次的孩子们中，上述风险的降幅最大。

The researchers, led by Dr. A. Lindsay Frazier of Dana-Farber/Children's Hospital Cancer Center in Boston, wrote: "Our study supports the hypothesis that early allergen exposure increases the likelihood of tolerance and thereby lowers the risk of childhood food allergy." They added that their data "support the recent decisions to rescind recommendations that all mothers avoid peanuts/total nuts during pregnancy and breast-feeding."

波士顿市达纳法伯/儿童医院癌症中心(Dana-Farber/Children's Hospital Cancer Center)的A·林赛·弗雷泽(A. Lindsay Frazier)博士及其领导下的研究人员写道：“我们的研究支持这一假说：对过敏原的早期接触可增加小儿对其产生耐受的可能，从而降低了儿童期食物过敏的风险。”他们又补充道，他们的数据“支持最近做出的一项决定，即，不再建议所有母亲在妊娠期和哺乳期间避免食用花生/所有坚果。”

The study was supported by Food Allergy Research and Education, a nonprofit, and published in December in JAMA Pediatrics.

该研究受到非营利性组织——食物过敏研究和教育组织(Food Allergy Research and Education)的支持，并发表于12月的《美国医学会期刊：儿科》(JAMA Pediatrics)上。

According to an accompanying editorial by Dr. Ruchi Gupta, an associate professor of pediatrics at Northwestern University, "some studies actually showed that avoiding peanuts during pregnancy increased the risk of a child developing peanut sensitization."

在相关的评论员文章中，西北大学(Northwestern University)的儿科副教授鲁奇·古普塔(Ruchi Gupta)博士表示：“一些研究表明，母亲在妊娠期避免接触花生的确会增加其子女对花生敏感的风险。”

Further support comes from studies of other common food allergens. In an Israeli study of 13,019 infants, those who were exposed to cow's milk protein as a breast-milk supplement in the first two weeks of life were less likely to become sensitive to it than infants first given cow's milk much later.

关于其他常见食物过敏原的研究进一步支持了上述结论。在以色列的一项涉及13019名婴儿的研究中，与很晚才第一次饮用牛奶的婴儿相比，在出生后两周内就以母乳为主牛奶为辅的婴儿由于较早接触到了牛乳蛋白，就不那么容易对牛奶敏感。

An Australian study of 2,589 babies found that those first introduced to egg at or near 1 year of age were more likely to develop an allergy to egg protein than those first given egg at 4 to 6 months of age.

澳大利亚的一项关于2589名婴儿的研究发现，与四至六个月大时就开始食用鸡蛋的婴儿相比，在一岁左右才第一次在辅食中引入鸡蛋的婴儿更容易出现卵蛋白过敏。

In her editorial, Dr. Gupta emphasized that further research was needed to understand how maternal diet affects the development of food allergies and "why more and more children are developing food allergy and how we can prevent it."

古普塔博士在她的评论文章中强调，仍需要进行进一步的研究，以了解孕产妇的饮食如何影响食物过敏症的产生，并为“为什么有越来越多的孩子发生食物过敏，对此我们应如何预防”等问题寻找答案。

But for now, she said, "pregnant women should not eliminate nuts from their diet, as peanuts are a good source of protein and also provide folic acid," which can help prevent neural tube defects.

但就目前而言，她认为“孕妇不应将坚果从食谱中删除，毕竟花生是蛋白质的良好来源，还可以提供叶酸”，而叶酸有助于预防神经管缺陷。