第九十四期杂志——终结谣言：旅行健康老话背后的科学

Cresarea

Myth busters: The science behind travel health clichés
终结谣言：旅行健康老话背后的科学

Is it true that going on an plane will make you sick? Can you avoid mosquito bites just because you’re a man? Doctor Jane is on the case to clarify the most baffling travel health myths…
坐飞机会让你生病是真的吗？因为你是男人就可以避免蚊子叮咬吗？简医生在这里会澄清最令人困惑的旅行健康老话……

Do vitamin B capsules, yeast, or foods rich in thiamine prevent mosquito bites?
摄入B族维生素、酵母或富含硫胺素的食物能预防蚊虫叮咬吗？

                               
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A hiker spraying mosquito repellent (Dreamstime)
一个徒步旅行者喷洒驱蚊剂 （Dreamstime）

Some websites claim that eating thiamine-rich food makes you repellent to blood-feeders. It doesn’t. However, thiamine (aka vitamin B1) does reduce itching caused by bites. Thiamine protagonists advise increasing dietary intake (eg more yeast products, offal or whole grains) and taking one brewer’s yeast tablet daily while in bug-infested places.
一些网站声称，吃富含硫胺素的食物能预防吸血昆虫的叮咬。其实不对。不过，硫胺素（即维生素B 1）确实能减少虫叮引起的瘙痒。硫胺素倡导者建议，身处蚊虫集中区域的时候，提高硫胺素的饮食摄入量（如进食更多的酵母产品，内脏或全谷类），而且每天都吃一片啤酒酵母片。

This strategy is okay if visiting midge-heavy Scotland or Scandinavia, for example, but it is unwise if heading for the tropics or even the Americas. Why? Because if biters are annoying, you’ll take avoiding action such as moving into a screened room or applying repellent. If you don’t notice the bites, however, you are more likely to do nothing and thus increase your risk of mosquito-borne disease, and there are several on offer (including West Nile fever) in the warmer parts of the US.
如果你去蚊虫很多的苏格兰或斯堪的纳维亚旅游参观，那么这种防虫策略是可以的；但如果你是去热带地区甚至是美洲，这种做法并不明智。为什么呢？因为如果蚊虫多到令人头痛的地步，一般你会倾向采取躲避策略，比如搬进有纱窗的房间或者涂上驱蚊剂。但是，如果你没有注意到蚊虫的叮咬，那你很可能什么也不做，反而增加了患蚊媒传染病的风险。其中有几种蚊媒传染病（包括西尼罗河热）就在美国较温暖的地区传播。

Do women get bitten by mosquitoes more than men?
女人会比男人更容易受蚊虫叮咬吗？

Sexist old-school explorers used to claim that the best way to avoid bites in the tropics was to bring along a woman. There is evidence that, given the choice, mosquitoes are attracted to female humans – especially pregnant women. Indeed, the latter are bitten twice as often as their non-pregnant peers.
男性至上的老派探险家曾声称，在热带地区不被蚊虫叮咬的最好方法就是带一个女人同行。有证据表明，如有选择余地，蚊虫更中意女性—尤其是孕妇。事实上，孕妇被叮的次数是未孕女性的两倍。

Increased skin temperature, surface area, hormones, and other ‘volatile substances’ seem to attract mosquitoes. They also home in on CO2 and are likely drawn to talkative people as they emit more of this gas. Being quiet isn’t a failsafe, though: mosquitoes will make do with quiet men, cats or even geckos. It is fascinating to watch mosquitoes hunting. Somehow they are aware that keeping in the shadows is safer than being out in the open. They will even bite amid the black areas of fur on a piebald cat rather than the white fur, seemingly knowing that they are easy to see against a white background.
皮肤温度升高、外露皮肤增加、激素水平上升和其他“挥发性物质”增加似乎能吸引蚊子。蚊子还以二氧化碳为生，所以它们也许会被健谈的人所吸引，因为这些人会释放出更多的二氧化碳。不过，保持沉默并非保险手段：蚊子照样叮咬安静的人、猫甚至壁虎。说实话看蚊子捕猎很有意思。不知怎么地，他们认为躲在暗处比待在户外更安全。蚊子甚至会咬一只花斑猫身上黑色的皮毛，而不是白色的皮毛，似乎是知道在白色的背景里它们很容易被发现。

Do travellers always get sick soon after a plane journey?
坐飞机旅行后旅游者总是很快生病吗？

                               
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Passengers waiting to board a plane in Italy (Dreamstime)
旅客在意大利等待登机

Airlines discourage flying with active infectious disease, but checks are few – and chickenpox and colds are often caught during air travel. The challenge is that chickenpox victims are highly infectious and breathe out large numbers of virus in the 24 hours before the rash appears – when they are unaware of being ill. Similarly, people developing colds and flu excrete viruses into the cabin air without realising how infectious they are.
虽然航空公司不允许患传染性疾病的乘客坐飞机，但很少有这方面的检查——于是人们也常在飞机上才被查出患有水痘和感冒。问题在于水痘患者具有高度传染性，且在皮疹出现前24小时会呼出大量病毒，而那时他们并不知道自己生病了。同样，感冒和流感患者也会将病毒呼出到机舱空气中，他们也不知道自己的传染性有多强。

HEPA (high efficiency particulate air) filters on modern aircraft have the capability of removing pathogens as small as viruses, but the air circulates along rows of seats, so there isn’t complete protection.
现代飞机上的高效空气过滤器（HEPA）能去除和病毒一样小的病原体，但空气是沿着成排座位循环的，因此并非完全保护。

Will a few drops of washing-up water on your plate make you desperately ill?
盘子里留有几滴洗碗水会让你患上重病吗？

Lots of travellers worry about the water that gets into their mouths, but when assessing the risk, it is worth remembering that most harmful microbes need to invade the body in their thousands, if not millions, to make themselves felt. Swallowing the odd drop of washing-up water, or brushing your teeth in tap water, isn’t likely to make you ill.
许多旅行者担心洗碗水会进入他们的口里。但若评估风险，我们该记住，大多数有害微生物都要成千上万地入侵身体才会让我们觉得有问题。所以，喝下几滴洗碗水，或者用自来水刷牙，都不会让你生病。

Firstly, foreign tap water is unlikely to be badly polluted (otherwise the locals would have been wiped out); and secondly, water that appears clean is unlikely to be wriggling with pathogens. I brush my teeth in Kathmandu tap water but boil water I’m going to drink. The risk is all about the amount of contamination.
首先，外国的自来水不太可能受到严重污染（否则当地人就会因为水质而出现问题）；其次，看起来干净的水不太可能有病原体存在。我在加德满都是用自来水刷牙，但喝烧开过的水。其实水引起疾病的风险取决于污染程度。

There is an exception in that Shigella bacteria – the bug that is responsible for bacillary dysentery – is very infective: swallowing just 100 Shigella will make most people really ill. That said, these bacteria are unlikely to contaminate a water supply unless there has been some dramatic infrastructural breakdown, of the kind experienced after floods or earthquakes.
有一个例外——志贺氏杆菌是一种导致痢疾的病菌，具有很强的传染性：吞下100个志贺氏菌就会让大多数人生病。尽管如此，这些细菌很少能污染供水系统，除非有洪水或地震导致基础设施严重损坏。

Can carrying your own cup and cutlery protect you?
自带杯子和餐具能有保护作用吗？

In a similar vein, using only your own cup and cutlery won’t especially protect you from acquiring infections; typically, gastroenteritis comes from poor food handling by cooks. It is possible to catch typhoid from sharing drinking vessels, but slurping from a clean cup or glass isn’t risky. Interestingly, in Nepal, where typhoid is quite common, people don’t put their mouths on water bottles or cups but pour and drink without contact.
同理可证，只使用自己的杯子和餐具并不能特别有效地保护你不受感染；一般来说，肠胃炎源于食物处理不当。与他人共用饮水器具可能会感染伤寒，但用干净的杯具饮水并不危险。有趣的是，在伤寒很常见的尼泊尔，人们喝水时并不会把嘴贴在瓶口或杯沿，而是直接把水倒进口里避免任何接触。

Will a mask protect you from infection?
口罩能保护你不受感染吗？

                               
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A family protecting themselves from air pollution in Hoi Chi Minh, Vietnam (Dreamstime)
越南胡志明市，一家子在空气污染里保护自己

Research has established that masks worn by surgeons during operations don’t protect anyone, yet they continue to be worn – and are beloved of the residents of polluted Kathmandu. While masks probably exist that filter out everything from microbes to chemical pollutants, masks that are effective and also comfortable to wear are hard to find. Mask-wearing is always a compromise; I wouldn’t wear one in a disease outbreak area but do wear one to sieve out some of the pollution when I’m cycling around cities – I cough less if I do.
研究表明，外科医生在手术过程中戴的口罩并不能保护任何人，但人们仍在继续戴口罩——口罩还深受污染地区加德满都居民的喜爱。虽然可能有口罩可以过滤所有微生物及化学污染物，但却很难找到既高效又舒适的口罩。戴口罩总是一个折衷办法；我可能不会在疾病爆发区戴口罩，但在我骑车绕城的时候，我肯定会戴一个来抵挡一些污染——这样我咳嗽会少一些。
Is it true that insect repellents ward off all insects but not other biters?
驱虫剂能驱除所有的昆虫，但对一些咬人的蚊虫无效，是真的吗？

Properly- and frequently-applied insect repellents keep off most blood-lusting small creatures, including leeches and ticks, despite the fact that they are not insects. Repellents don’t work on all insects, though; houseflies, wasps and bees don’t take much notice. If troubled by flies in a restaurant, ask if they’ll light a candle; in my experience, flies avoid burning wax.
一些常用且用法正确的驱虫剂可以阻挡大多数嗜血的小生物，包括水蛭和扁虱，尽管它们不是昆虫。不过，驱虫剂并不是对所有昆虫都起作用：像是对家蝇、黄蜂和蜜蜂就没什么作用。不过，如果你在餐馆里受到苍蝇的困扰，就问餐馆人员能否点燃蜡烛；根据我的经验，苍蝇会避开燃烧的蜡烛。

Is a post-travel check-up worth doing?
旅行后的身体检查值得做吗？

Tests for schistosomiasis and HIV are worth doing if you’ve respectively bathed in African lakes or had an encounter that has led to unsafe sex, but the evidence is that routine check-ups don’t have much value if you are symptom-free.
如果你在非洲的湖泊里泡过或有一场不保障安全的艳遇，那么值得参加针对血吸虫病和艾滋病毒的检测。不过有证据表明，如果你是无症状感染，常规检查可能没有多大价值。

文章来源：https://www.wanderlust.co.uk/con ... -myths-doctor-jane/

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校对by 旺仔
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penz

呵呵，原来如此