一位俄羅斯姑娘在從莫斯科郊外遊玩回來之後發現，她被蚊子叮咬的包居然會移動？
A 32-year-old Russian woman found a mysterious migrating mosquito bite on face, which was later diagnosed as a parasite, according to the New England Journal of Medicine’s case report on June 21.
這個包在兩週之內，從左眼下方，移動到左眼上方，又移動到了嘴唇上。她將這個“神奇”的包用自拍記錄了下來。醫生一看卻隨即發現，這是寄生蟲！
被蚊子叮咬的包會移動？是寄生蟲！
世界頂級醫學期刊《新英格蘭醫學雜誌》(The New England Journal of Medicine)於上週四收錄了一個新病例。
一位32歲的俄羅斯姑娘最近發現，臉上被蚊子叮咬的包會居然移動。
The patient captured her symptoms through selfies. The nodule was found below her left eye at first. Five days later, it moved to left eye’s upper eyelid. Ten days after that, the nodule appeared again, but was located differently. This time, it was on her lip.
最開始，這個包出現在眼睛下方；五天後，又移動到了眼皮上面；十天後，嘴唇又腫了起來。這個小包與被蚊子叮咬後出現的包非常相似，它經常在幾分鐘之內出現，並伴有灼熱、瘙癢，又在短時間內消失。除此之外，並無其他明顯不適或症狀。
The nodule was oblong, tender, and with an occasional localized itching and burning sensation, but with no other symptoms. It appeared and disappeared in minutes, just like normal mosquito bites, except that it can migrate.
不堪其擾的她在兩週後決定就醫。幸運的是，她遇到了一位很有經驗的醫生。俄羅斯羅斯托夫國立醫科大學的醫學教授Dr. Vladimir Kartashev很快確診了姑娘的病並非尋常蚊蟲叮咬，而是感染了匐行惡絲蟲(Dirofilaria repens)。
The nodule was diagnosed as an infection of the Dirofilaria repens, a zoonotic filarid nematodes in the genus Dirofilaria.
“我至少看到過10個這樣的案例，”教授說，“這樣的‘非常規移動’真的十分具有迷惑性，紅腫經常在幾分鐘之內出現，又在幾分鐘之後消失。經驗不足的醫生往往不會相信這樣的說辭。這也是我讓她自拍記錄病情的原因”。
The doctor, Dr. Vladimir Kartashev, a professor of medicine at Rostov State Medical University, told CNN in an email that he had seen at least 10 patients with the same presentation before. But doctors who are not familiar with the disease may not believe the patients since idea of it “migrating” is extremely confusing.
確診後，教授隨即為姑娘做了一場“小手術”——用鑷子將寄生蟲取了出來。整個過程不超過15分鐘。由於惡絲蟲在人體內不具備繁殖能力，在蟲體取出後姑娘已經痊癒。
The parasite worm has been removed from the patient with forceps, using local anesthesia. The trivial surgery took only less than 15 minutes. To remove the parasite through a small incision is a kind of common approach to cure the Dirofilaria repens infected patients, the doctor added.
在醫生的詢問下，姑娘回憶起自己近期曾在莫斯科的郊外遊玩，並且受到了頻繁的蚊子叮咬，應該就是在那時感染上的寄生蟲。
As recalled by the patient, she had traveled to a rural area outside Moscow not long ago, where she was frequently bitten by mosquitoes.
惡絲蟲“家族”和人類
匐行惡絲蟲，屬於惡絲蟲屬。它的近親還包括細弱惡絲蟲、犬惡絲蟲、厄氏惡絲蟲、皮下絲蟲、條紋絲蟲等，是一種宿主為犬及其他肉食性動物的寄生蟲。
According to the US Centers for Disease Control and Prevention (CDC), the worms’ normal hosts in nature are usually carnivores, especially dogs. Humans are only accidental hosts entered through larva from mosquito bites, where the parasite can’t develop or is infertile.
在極少數情況下，惡絲蟲可由蚊蟲叮咬傳染給人類，並出現皮下、結膜腫塊、蕁麻疹或淋巴炎等症狀。在中國通常統稱惡絲蟲病。中國於2011年到2012年之間在香港發現三起“香港型惡絲蟲”感染案例，已經屬於較大範圍的感染。
根據美國疾病預防控制中心(CDC)的定義，匐行惡絲蟲、厄氏惡絲蟲、以及細弱惡絲蟲在進入人體後，一般會在皮下組織中游移或者形成肉芽型紅腫，但也有曾進入肺部的案例。其中比較明顯的特徵就是產生“可移動”的柔軟橢圓形皮下紅腫，並伴隨疼痛、灼熱、瘙癢等症狀，就像這次不幸中招的俄羅斯姑娘一樣。
As stated by the CDC, Dirofilaria repens usually does not cause serious symptoms or fatal illnesses in humans. They wander in the subcutaneous tissue or present as a large nodule. Only a few cases were reported that the parasite caused pulmonary diseases.
而感染它們的近親，犬惡絲蟲，病情則會稍嫌嚴重。它們在進入人體後會遵循和在最終宿主體內一樣的遷移模式，進入人體肺部，寄宿於小血管中，造成血管梗塞和硬幣性病變（孤立性肺結節），這種病變可通過X光片觀察到，進而引起胸痛、咳嗽、發燒、渾身發冷、咳血等症狀。
However, patients who got caught by its “relatives”, known as the Dirofilaria immitis, may seem comparably unfortunate. The species, following embolization, will largely follow the same migratory pathway in the canine host, and eventually residing in small-caliber vessels in the lungs. The parasite will then cause infarcts and “coin lesions” following chest pains, coughing, fevers, chills, and other complications.
發育成熟的匐行惡絲蟲身長可達到170毫米，犬惡絲蟲可達到310毫米，並存活5到10年之久。從世界的範圍來看，歐洲、亞洲、非洲是匐行惡絲蟲的三大中招重災區。
According to CDC, the length of the adult parasite can be as long as 170 mm for Dirofilaria repens and 310mm for Dirofilaria immitis respectively. Both of them can live up to 10 years. Although it is rare for humans to contract the worm, cases have been mostly reported in the past from places such as Asia, Europe and Africa.
由於人類並非惡絲蟲的最終宿主，所以它們並不會在體內繁殖，也不會人傳人，在大多數情況下病人不會有即時的生命危險。並且，人類感染惡絲蟲的病例十分罕見，所以不用太過恐慌和擔心。
怎樣預防？
由於惡絲蟲病主要通過蚊蟲叮咬的途徑感染人類，所以最簡單的預防就是避免蚊蟲叮咬。如果想要用藥物預防，還是需要諮詢專業的醫生。
The simplest way to guard against the parasite is to protect yourself from insect bites and stings. Also, for people who have dogs as pets, it is crucial to get them vaccinated at regular intervals.
另外，比起人類，惡絲蟲病對犬類的危害嚴重太多，這也是為什麼惡絲蟲又經常被稱為“犬心絲蟲”的原因。
作為惡絲蟲的最終宿主，惡絲蟲不僅會在犬類體內發育和繁殖，還會進入犬類心臟以及其他內臟，對犬類心肺造成不可逆轉的致命損傷。
所以，養寵物的朋友一定切記定期給家裡犬類進行驅蟲和免疫，儘量避免讓寵物在蚊蟲聚集的野外玩耍。
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