This is no regular forest.

這可不是普通的森林。

Living where the scalp meets the hair, these nightmarish figures are in fact sesame seed-sized insects, otherwise known as head lice.

這些噩夢般的身影生活在頭皮和頭髮的交界處，實際上是芝麻大小的昆蟲，也就是我們常說的頭蝨。

The earliest archaeological evidence of humans' close-knit relationship with lice is a fully preserved egg, discovered in the hair of a 10,000-year-old Brazilian mummy.

人類與蝨子關係密切的最早考古證據是在一具 1 萬年前的巴西木乃伊的頭髮中發現的一枚保存完好的卵。

And it seems that for as long as we've had lice, we've fought hard to get rid of them.

看來，只要我們有蝨子，我們就一直在努力擺脫它們。

Knit combs, the fine-toothed brushes used to remove lice and their sticky eggs, have been found among the ancient remains of cultures across the globe.

編織梳是一種細齒刷子，用於清除蝨子及其粘性蟲卵，在全球各地的古代文化遺存中都有發現。

This battle continues today, as it's estimated we spend billions of dollars each year treating infestations.

這場戰爭一直持續到今天，據估計，我們每年都要花費數十億美元來治療蟲害。

So why are lice so difficult to get rid of?

那麼，為什麼蝨子如此難除？

There are at least several thousand louse species, as nearly all mammals deal with these parasites.

蝨子的種類至少有幾千種，因為幾乎所有哺乳動物都要與這些寄生蟲打交道。

Humans are pestered by three different types, each specialized to roam its own unique bodily terrain.

人類受到三種不同類型的生物的糾纏，每種生物都有自己獨特的身體特徵。

Pediculus humanus capitis live exclusively on heads and are equipped with hook-like claws that are perfectly fitted to human scalp hair.

人頭癬菌只生活在頭部，它們長著鉤狀的爪子，非常適合人類的頭皮毛髮。

Pediculus humanus humanus, or body lice, spend most of their lives embedded in clothing and bedding, and crawling onto any nearby body part for their feedings.

人體蝨（Pediculus humanus humanus），又稱體蝨，一生中大部分時間都寄生在衣物和床上用品中，並爬到附近的任何身體部位取食。

In order to thrive in these changing environments, body lice are more resilient to fluctuations in temperatures and humidity.

為了在這些不斷變化的環境中茁壯成長，體蝨對溫度和溼度的波動有更強的適應能力。

Meanwhile, pubic lice, also known as crab lice, are an entirely different species.

與此同時，陰蝨又稱蟹蝨，是完全不同的物種。

While they also live on hair, their claws are larger than head lice, as they're fitted to grasp onto the thicker cuticles found in pubic areas.

雖然它們也生活在頭髮上，但它們的爪子比頭蝨大，因為它們適合抓住陰部較厚的角質層。

Among these three varieties, head lice are the most common.

在這三種蝨子中，頭蝨最為常見。

In the U.S. alone, it's estimated 6 to 12 million children deal with infestation each year.

據估計，僅在美國，每年就有 600 萬到 1200 萬兒童受到蟲害的困擾。

Contrary to popular fears about catching lice from hats or hairbrushes, most cases spread through direct head-to-head contact.

與人們擔心從帽子或梳子上感染蝨子相反，大多數情況下，蝨子是通過頭對頭的直接接觸傳播的。

You see, head lice can only survive about 24 hours without a host to feed on.

要知道，頭蝨在沒有寄主的情況下只能存活 24 小時左右。

They're wingless and they can't jump, so the only way they can infest a new head is to crawl.

它們沒有翅膀，也不會跳躍，所以唯一的辦法就是爬行。

They can detect a new host by using their antennae to home in on body heat and other chemical compounds that naturally emanate from the scalp.

它們可以用觸角捕捉體溫和頭皮自然散發的其他化學物質，從而發現新的宿主。

Once they arrive on a new head, they're ready to eat.

一旦它們到達新的頭部，就可以吃了。

A louse pierces the scalp with a retractable, tube-like mouth and releases a special saliva that contains factors that open up blood vessels and help prevent clotting.

蝨子用可伸縮的管狀嘴刺穿頭皮，並釋放出一種特殊的唾液，這種唾液含有能打開血管並有助於防止凝血的因子。

This chemical cocktail is also what makes the scalp feel itchy.

這種化學雞尾酒也是導致頭皮發癢的原因。

Symbiotic bacteria living in louse's gut complement this blood meal by providing the additional vitamins and minerals that the louse needs to survive.

生活在蝨子腸道中的共生細菌提供了蝨子生存所需的額外維生素和礦物質，從而補充了這種血餐。

The scalp is also where lice mate.

頭皮也是蝨子交配的地方。

Once mated, female lice can lay up to eight eggs, called nits, per day.

一旦交配，雌蝨每天最多可產卵 8 個，稱為蝨卵。

She deposits each egg on the hair just a few millimeters above the scalp and coats it with a sticky, knit sheath, which provides hydration and other factors the egg needs to survive.

它把每顆卵都放在頭皮上方几毫米處的頭髮上，並在卵上覆蓋一層粘性的針織鞘，為卵提供水分和其他存活所需的因素。

This sheath hardens, tightly cementing the nit to the hair until it hatches eight to ten days later.

這種鞘會變硬，將蝨子緊緊粘在頭髮上，直到八到十天後孵化。

You can't get rid of a lice infestation without taking care of this sticky egg problem.

不解決粘卵問題，就無法擺脫蝨子的困擾。

While insecticide shampoos kill hatched lice, they're ineffective against eggs.

雖然殺蟲劑洗髮水能殺死孵化的蝨子，但對蝨卵卻無效。

And knit sheaths are strong, waterproof, and resistant to chemical breakdown.

針織護套結實、防水、耐化學腐蝕。

Scientists hope to bring some new tools to this old battle by identifying treatments that can dismantle individual components in the knit sheath, like those that hydrate the egg and keep it alive.

科學家們希望為這場古老的戰鬥帶來一些新工具，方法是確定能夠破壞針織鞘中單個成分的治療方法，比如那些為卵子補充水分並使其存活的成分。

But until then, there's only one tool that's been shown to effectively remove eggs.

但在此之前，只有一種工具能有效去除卵子。

And it's the same one that was used by ancient cultures, a fine-toothed knit comb.

這也是古代文化中使用的一種細齒編織梳。

Lice are certainly stubborn survivors.

蝨子當然是頑強的倖存者。

But perhaps one day, with the help of science, these ancient parasites will haunt our nightmares and scalps no more.

但也許有一天，在科學的幫助下，這些古老的寄生蟲將不再困擾我們的噩夢和頭皮。

Do you ever feel like you don't know enough about your own body?

你是否曾覺得自己對自己的身體不夠了解？

Subscribe to this channel to learn about everything from baldness to muscle growth to why we have hair in such random places.

訂閱本頻道，瞭解從禿頂到肌肉生長的一切知識，以及為什麼我們的頭髮長在如此隨意的地方。

Stay tuned and stay curious.

敬請關注，保持好奇。