爲什麼有這麼多孩子對花生過敏

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.

近年來，花生過敏症日益威脅着孩子們的健康，這不僅迫使越來越多的家長不得不將所有堅果都清除出家庭環境，還促使不少學校將兒童時代的主食之一——花生醬請出了餐廳。

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.

當一個孩子對花生過敏時，無論家裏家外，他的家人都必須密切監控他塞進嘴裏的任何東西，因爲一不小心吃到花生就很可能有生命危險。許多航空公司的餐飲中都不再提供花生，以免對此過敏的乘客吸入花生粉末，以致在30000英尺（約9144米）的高空出現危及生命的過敏反應。

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.

紐約市西奈山醫院(Mount Sinai Hospital)一名食物過敏症專科醫生的研究表明，美國兒童中的花生過敏症患病率從1997年的0.4%上升到了2010年的1.4%，增加了兩倍還多。大多數花生過敏症患者同時也對一或多種堅果，如核桃、美洲山核桃或杏仁等過敏。

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.

爲了防止這類人不至於意外接觸到堅果，袋裝食品的標籤往往會主動聲明該食品的生產設備是否也用於處理堅果。

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.

一些城市設有無堅果麪包店，以向過敏的孩子們銷售特殊、安全（但昂貴）的蛋糕或杯子蛋糕，供他們在參加聚會時攜帶。

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.

雖然關於是否有必要採取某些極端措施來防止間接接觸花生，專家們持懷疑態度，但食用含有花生成分的食物對花生過敏症患者而言無疑十分危險。

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.

當兒童第一次接觸到花生時，可能會發生一種具有潛在致命性的反應，稱爲過敏反應(anaphylaxis)，其表現爲：瘙癢、舌頭和咽喉腫脹、氣道收縮、血壓驟降、心率加快、昏厥、噁心嘔吐等。

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.

如不及時通過注射腎上腺素遏制該反應，過敏反應可能導致死亡。1986年，布朗大學(Brown University)發生了一起著名的慘痛案例：18歲的大一新生凱瑟琳·布羅德斯基(Katherine Brodsky)對堅果過敏，她因在餐廳食用了用花生醬加稠的咖喱而死亡。

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.

目前尚沒有辦法可以徹底治癒堅果過敏，但若干初步研究表明，採用免疫療法或可緩和患者對花生的反應。這種方法與對付花粉過敏的方法類似：患者從舌下接觸微量具有刺激性的花生蛋白開始，隨後在嚴格的醫療監督下逐步加量。

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.

最近的一項研究在英國劍橋(Cambridge)進行，並於上週發表在《柳葉刀》雜誌(The Lancet)上。該研究發現，在接受口服免疫療法半年後，七至16歲的兒童中有91%可在一天內食用五顆左右的花生，且不會出現嚴重不良反應，這一安全攝取量遠遠超過了治療前的水平。在接受治療的兒童中約有五分之一在食用花生後仍會出現反應，但其大多數都非常輕微，通常只是嘴部發癢而已。在所研究的99名兒童中，只有一人出現了嚴重反應。

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.

該研究顯示，當免疫療法起效時，過敏的嚴重程度有所減輕，這使過敏患者得以安全地攝取少量具有刺激性的蛋白質。目前尚不清楚在中止免疫療法後這種保護作用還可以持續多久，但研究人員警告說，任何人都不應擅自進行此類嘗試。若干年後，該療法也許能夠進入臨牀應用，但在此之前，還需要進一步的研究。

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

此外，專家們建議，每一位花生過敏症患者都應隨身攜帶EpiPen（預裝腎上腺素的自動注射器），以備在必要時進行急救。

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.

在理想情況下，過敏症專科醫生希望能將花生過敏扼殺在搖籃裏。專家們認爲，其方法之一是嚴格限制妊娠期和哺乳期婦女對花生食品的攝取，從而避免胎兒和母乳餵養期的嬰兒接觸到花生蛋白。

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.

爲數衆多不同的研究表明，具有過敏傾向的嬰兒過早地接觸到花生蛋白很可能會引起致敏，繼而導致嚴重的花生過敏。2000年，專家們建議：孕婦和哺乳期婦女應避免食用花生，對於具有過敏性疾病史的家庭尤其如此。他們還告誡新媽媽們：在寶寶年滿三歲，消化系統充分發育前，不要給他們吃花生。

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

但這些建議絲毫未能遏制花生過敏症病例穩步攀升的趨勢，因此，它們在2008年被撤銷。

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，人們對付過敏症的思路與之前的完全背道而馳。人們不再嚴格限制未出生或哺乳期的嬰兒接觸花生蛋白，相反，人們認爲，當孕婦或哺乳期婦女食用花生時，進入寶寶血液循環裏的微量花生蛋白將誘導免疫耐受，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.

在一項涉及8205名兒童（其中140人對堅果過敏）的近期研究中，研究人員發現，自身不過敏，且在妊娠期食用花生和/或堅果量最高的母親所生下的孩子日後發生過敏症的風險最低。在母親每個月至少食用堅果五次的孩子們中，上述風險的降幅最大。

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."

波士頓市達納法伯/兒童醫院癌症中心(Dana-Farber/Children's Hospital Cancer Center)的A·林賽·弗雷澤(A. Lindsay Frazier)博士及其領導下的研究人員寫道：“我們的研究支持這一假說：對過敏原的早期接觸可增加小兒對其產生耐受的可能，從而降低了兒童期食物過敏的風險。”他們又補充道，他們的數據“支持最近做出的一項決定，即，不再建議所有母親在妊娠期和哺乳期間避免食用花生/所有堅果。”

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

該研究受到非營利性組織——食物過敏研究和教育組織(Food Allergy Research and Education)的支持，並發表於12月的《美國醫學會期刊：兒科》(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."

在相關的評論員文章中，西北大學(Northwestern University)的兒科副教授魯奇·古普塔(Ruchi Gupta)博士表示：“一些研究表明，母親在妊娠期避免接觸花生的確會增加其子女對花生敏感的風險。”

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.

關於其他常見食物過敏原的研究進一步支持了上述結論。在以色列的一項涉及13019名嬰兒的研究中，與很晚才第一次飲用牛奶的嬰兒相比，在出生後兩週內就以母乳爲主牛奶爲輔的嬰兒由於較早接觸到了牛乳蛋白，就不那麼容易對牛奶敏感。

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.

澳大利亞的一項關於2589名嬰兒的研究發現，與四至六個月大時就開始食用雞蛋的嬰兒相比，在一歲左右才第一次在輔食中引入雞蛋的嬰兒更容易出現卵蛋白過敏。

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."

古普塔博士在她的評論文章中強調，仍需要進行進一步的研究，以瞭解孕產婦的飲食如何影響食物過敏症的產生，併爲“爲什麼有越來越多的孩子發生食物過敏，對此我們應如何預防”等問題尋找答案。

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，她認爲“孕婦不應將堅果從食譜中刪除，畢竟花生是蛋白質的良好來源，還可以提供葉酸”，而葉酸有助於預防神經管缺陷。