日: 回虫
ラ: Ascaris lumbricoides
同: roundworm
関: 蠕虫、アスカリス属
関: Ascaridida、Ascaridoidea、Ascaris、lumbricoides、lumbricus、round worm、roundworm
関: Ascaris、Ascaris lumbricoides、lumbricoides、lumbricus、round worm

関: 回虫属、蛔虫、貧毛網、回虫目、回虫上科

虫卵の大きさ

大型虫卵：肝蛭卵(150-190x75-95μm)
やや大型虫卵：回虫不受精卵
中型虫卵：回虫卵受精卵(45-75x30-50μm)、鉤虫卵
やや小型虫卵：蟯虫卵
小型虫卵：肝吸虫卵

WordNet

type genus of the family Ascaridae: roundworms with a three-lipped mouth (同)genus Ascaris

PrepTutorEJDIC

回虫

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/10/02 15:05:57」(JST)

wiki en

[Wiki en表示]

Ascaris lumbricoides is the giant roundworm of humans, belonging to the phylum Nematoda. An ascarid nematode, it is responsible for the disease ascariasis in humans, and it is the largest and most common parasitic worm in humans. One-sixth of the human population is estimated to be infected by Ascaris lumbricoides or another roundworm.^[1] Ascariasis is prevalent worldwide and more so in tropical and subtropical countries.

It can reach a length of up to 35 cm.^[2]

Life cycle[edit]

Ascaris lumbricoides, or "roundworm", infections in humans occur when an ingested fertilised egg becomes a larval worm that penetrates the wall of the duodenum and enters the blood stream. From here, it is carried to the liver and heart, and enters pulmonary circulation to break free in the alveoli, where it grows and molts. In 3 weeks, the larvae pass from the respiratory system to be coughed up, swallowed, and thus returned to the small intestine, where they mature to adult male and female worms. Fertilization can now occur and the female produces as many as 200,000 eggs per day for a year. These fertilized eggs become infectious after 2 weeks in soil; they can persist in soil for 10 years or more.^[3]

The eggs have a lipid layer which makes them resistant to the effects of acids and alkalis as well as other chemicals. This resilience helps to explain why this nematode is such a ubiquitous parasite.^[4]

Morphology[edit]

Fertile egg as can be seen in a microscope

Fertile egg in human faeces (detail)

Infertile egg

Ascaris lumbricoides is characterized by its great size. Males are 2–4 mm in diameter and 15–31 cm long. The males' posterior end is curved ventrally and has a bluntly pointed tail. Females are 3–6 mm wide and 20–49 cm long. The vulva is located in the anterior end and accounts for about a one third of its body length. Uteri may contain up to 27 million eggs at a time with 200,000 being laid per day. Fertilized eggs are oval to round in shape and are 45-75 micrometers long and 35-50 micrometers wide with a thick outer shell. Unfertilized eggs measure 88-94 micrometers long and 44 micrometers wide.^[5]

Epidemiology[edit]

More than 2 billion people are affected by this infection.^[3] In the United States there is a reported prevalence of 0.8% of the total population as of 1987. Ascaris lumbricoides eggs are extremely resistant to strong chemicals, desiccation, and low temperatures. The eggs can remain viable in the soil for several months or even years.^[5]

Eggs of A. lumbricoides have been identified in archeological coprolites in the Americas, Europe, Africa, the Middle East, and New Zealand, the oldest ones being more than 24,000 years old.^[6]

Infections[edit]

Main article: Ascariasis

Infections with these parasites are more common where sanitation is poor^[7] and raw human feces are used as fertilizer.

Symptoms[edit]

Often, there are no symptoms with an A. lumbricoides infection. However, in the case of a particularly bad infection, symptoms may include bloody sputum, cough, fever, abdominal discomfort, passing worms, etc.^[8]^[9]

Prevention[edit]

Preventing any fecal-borne disease requires educated hygienic habits/culture and fecal treatment systems once a year. This is particularly important with ascaris because its eggs are one of the most difficult pathogens to kill (second only to prions), and the eggs commonly survive 1–3 years. Ascaris lives in the intestine where it lays eggs. Infection occurs when the eggs, too small to be seen by the unaided eye, are eaten. The eggs may get onto vegetables when improperly processed human feces of infected people are used as fertilizer for food crops. Infection may occur when food is handled without removing or killing the eggs on the hands, clothes, hair, raw vegetables/fruit, or cooked food that is (re)infected by handlers, containers, etc. Bleach does not readily kill Ascaris eggs but it will remove their sticky film, to allow the eggs to be rinsed away. Ascaris eggs can be reduced by hot composting methods, but to completely kill them may require rubbing alcohol, iodine, specialized chemicals, cooking heat, or "unusually" hot composting (for example, over 50°C (120°F) for 24 hours [1]).

Details of infection process[edit]

Infections happen when a human swallows water or food contaminated with unhatched juveniles. The juveniles hatch in the duodenum. They then penetrate the mucosa and submucosa and enter venules or lymphatics. Next they pass through the right heart and into pulmonary circulation. They then break out of the capillaries and enter the air spaces. Acute tissue reaction occurs when several worms get lost during this migration and accumulate in other organs of the body. The juveniles migrate from the lung up the respiratory tract to the pharynx where they are swallowed. They begin producing eggs within 60–65 days of being swallowed. These are produced within the small intestine where the juveniles mature. It might seem odd that the worms end up in the same place where they began. One hypothesis to account for this behavior is that the migration mimics an intermediate host, which would be required for juveniles of an ancestral form to develop to the third stage. Another possibility is that tissue migration enables faster growth and larger size, which increases reproductive capacity.^[10]

Diagnosis and treatment[edit]

Most diagnoses are made by identifying the appearance of the worm or eggs in feces. Due to the large quantity of eggs laid, physicians can diagnose using only one or two fecal smears.

Infections can be treated with drugs called ascaricides. The treatment of choice is mebendazole. The drug functions by binding to tubulin in the worms' intestinal cells and body-wall muscles. Nitazoxanide and ivermectin can also be used.^[5]

References[edit]

^ Harhay MO, Horton J, Olliaro PL (February 2010). "Epidemiology and control of human gastrointestinal parasites in children". Expert Review of Anti-infective Therapy 8 (2): 219–34. doi:10.1586/eri.09.119. PMC 2851163. PMID 20109051.
^ "eMedicine - Ascaris Lumbricoides : Article by Aaron Laskey". Archived from the original on 27 January 2008. Retrieved 2008-02-03.
^ ^a ^b Murray, Patrick R.; Rosenthal, Ken S.; Pfaller, Michael A. Medical Microbiology, Fifth Edition. United States: Elsevier Mosby, 2005
^ Piper R (2007). Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals, Greenwood Press.
^ ^a ^b ^c Roberts, Larry S.; Janovy, John Jr. Foundations of Parasitology, Eight Edition. United States: McGraw-Hill, 2009
^ Dridelle R. Parasites. Tales of Humanity's Mostly Unwelcome Guests. Univ. of California, 2010. p. 26. ISBN 978-0-520-25938-6.
^ "DPDx - Ascariasis". Archived from the original on 24 February 2008. Retrieved 2008-02-03.
^ http://www.nlm.nih.gov/medlineplus/ency/article/000628.htm
^ http://www.stanford.edu/group/parasites/ParaSites2005/Ascaris/JLora_ParaSite.htm#Symptoms
^ Read, A.F.; Skorping, A. 1995. The Evolution of Tissue Migration by Parasitic Nematode Larvae. Parasitology 111:359-371

External links[edit]

Ascaris lumbricoides Video - DAVE Project
Ascaris lumbricoides image library

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. 回虫症 ascariasis
2. 回虫症の肺症状 pulmonary manifestations of ascariasis
3. 駆虫薬療法 anthelminthic therapies
4. 胆道寄生虫症の内視鏡診断およびマネージメント endoscopic diagnosis and management of biliary parasitosis
5. 蟯虫症および鞭虫症 enterobiasis and trichuriasis

English Journal

Advances with the Chinese anthelminthic drug tribendimidine in clinical trials and laboratory investigations.

Xiao SH, Utzinger J, Tanner M, Keiser J, Xue J.SourceNational Institute of Parasitic Diseases, Chinese Center for Diseases Control and Prevention, Shanghai 200025, People's Republic of China. shxiao4@hotmail.com
Acta tropica.Acta Trop.2013 May;126(2):115-26. doi: 10.1016/j.actatropica.2013.01.009. Epub 2013 Jan 23.
The anthelminthic drug tribendimidine has been approved by Chinese authorities for human use in 2004, and a first comprehensive review was published in Acta Tropica in 2005. Here, we summarise further advances made through additional clinical trials and laboratory investigations. Two phase IV trials
PMID 23352956

Parasitic diseases of the pleura.

Lal C, Huggins JT, Sahn SA.SourceDivision of Pulmonary, Critical Care, Allergy and Sleep Medicine, Medical University of South Carolina, Charleston, South Carolina.
The American journal of the medical sciences.Am J Med Sci.2013 May;345(5):385-9. doi: 10.1097/MAJ.0b013e318266e984.
: Parasitic infections are prevalent in certain parts of the world and may cause pleural involvement, which often goes unrecognized. Common parasites involving the pleura include Entamoeba histolytica, Echinococcus granulosus and Paragonimus westermani. Amebiasis can cause empyema with "anchovy sauc
PMID 22990049

Diagnosis of Ascaris lumbricoides infection using capsule endoscopy.

Yamashita ET, Takahashi W, Kuwashima DY, Langoni TR, Costa-Genzini A.SourceEduardo Tomohissa Yamashita, Wagner Takahashi, Daniel Yuiti Kuwashima, Tiago Ribeiro Langoni, Adriana Costa-Genzini, Advanced Center of Diagnostic and Therapeutic Endoscopy, UNIMED Santa Helena Hospital, 01508-000 São Paulo, Brazil.
World journal of gastrointestinal endoscopy.World J Gastrointest Endosc.2013 Apr 16;5(4):189-90. doi: 10.4253/wjge.v5.i4.189.
Ascaris lumbricoides (A. lumbricoides) is the most common intestinal roundworm parasite, infecting approximately one quarter of the world's population. Infection can lead to various complications because it can spread along the gastrointestinal tract. Although A. lumbricoides infection is a serious
PMID 23596544

Japanese Journal

The Half-life of Ascaris lumbricoides Prevalence in Japanese School Children

Kurosawa Carmen Miwa,Ito Takehiko,Takaki Jiro,Wang Bing-Ling,Wang Da-Hong,Takigawa Tomoko,Ogino Keiki
Acta Medica Okayama 62(5), 303-312, 2008-10
… The exponential decay of Ascaris lumbricoides prevalence was calculated by iterative least-squares method. …
NAID 120002305902

Acute large bowel obstruction due to Ascaris lumbricoides in a child from Sri Lanka

GUNAWARDENA Subhashana A.,GUNAWARDENA G. Sharmini A.
Tropical medicine and health 36(1), 41-43, 2008-03-01
NAID 10024174948

Helminthiasis in Pregnancy in Enugu, Nigeria

Ozumba Uchenna Chinedu,Ozumba Nwora Abiodun,Anya Samuel
Journal of health science 51(3), 291-293, 2005-06-01
… The prevalence of helminthic infection was 11.8% with only Ascaris lumbricoides (8.7%) and Trichuris trichuria (3.1%) being detected. …
NAID 10016657456

ネパールにおける感染症に関する研究 : ネパール王国の首都カトマンドゥーにおける小学校学童の寄生虫卵保有調査

石山聡子,柳田潤一郎,ライシバクマ,小野一男
神戸常盤短期大学紀要 26, 55-58, 2005-03-31
… A high prevalent rate was found for Ascaris lumbricoides (33.6%), Trichuris trchiura (21.3%) and Giardia intestinalis (11.5%). …
NAID 110004500351

Related Pictures

★リンクテーブル★

リンク元	「蠕虫」「アスカリス属」「lumbricus」「round worm」「Ascaridoidea」
関連記事	「lumbricoides」

「蠕虫」

Ascaris lumbricoides
	An adult female Ascaris worm.
Scientific classification
Kingdom:	Animalia
Phylum:	Nematoda
Class:	Secernentea
Order:	Ascaridida
Family:	Ascarididae
Genus:	Ascaris
Species:	A. lumbricoides
Binomial name
	Ascaris lumbricoides; Linnaeus, 1758

　　[★]

英: helminth, worms
ラ: helminthen
関: 微生物学、蠕虫症、家畜伝染病予防法

蠕虫類

吸虫類 trematoda
条虫類 cestoda
線虫類 nematoda
鉤頭虫類 acanthocephala

蠕虫類と感染症

蠕虫類	病原体名		病名	感染経路	寄生部位	症状	診断	治療
線虫類	Ancylostoma duodenale	ズビニ鉤虫	鈎虫症/十二指腸虫症	F型幼虫経口感染、経皮	空腸上部	皮膚炎、若菜病、貧血	飽和食塩水浮遊法、遠心沈降法	pyrantel pamoate、鉄剤
	Necator americanus	アメリカ鉤虫	鈎虫症/十二指腸虫症	F型幼虫経口感染、経皮	空腸上部	皮膚炎、若菜病、貧血	飽和食塩水浮遊法、遠心沈降法	pyrantel pamoate、鉄剤
	Strongyloides stercoralis	糞線虫	糞線虫症	F型幼虫経皮感染	小腸上部	Loffler症候群	糞便塗沫、普通寒天平板培養による R型、F型幼虫の検出	thiabendazole, ivermectin
	Enterobius vermicularis	蟯虫	蟯虫症	虫卵経口感染	盲腸～大腸	夜間の掻痒、不眠、情緒不安定	肛囲検査法「柿の種」	pyrantel pamoate
	Ascaris lumbricoides	回虫	回虫症	虫卵経口感染	小腸孵化→門脈→ 肺発育→食道嚥下→小腸	Loffler症候群。急性腹痛	糞便虫の虫卵の証明	pyrantel pamoate
	Toxocara canis	イヌ回虫	幼虫移行症	生後1-2ヶ月の感染犬の糞から経口感染	なし	幼虫移行症→失明	免疫診断	治療法無し？
	Wuchereria bancrofti	バンクロフト糸状虫	フィラリア症/糸状虫症	アカイエカ	リンパ系	急性期：リンパ肝炎、リンパ腺炎を伴う熱発作(filarial fever) 慢性期：乳糜尿、リンパ管瘤、陰嚢水腫、象皮病	急性期：夜間のmicrofilariaの検出慢性期：特有の症状を考慮	diethylcarbamazine & ivermectin
	Brugia malayi	マレー糸状虫	フィラリア症/糸状虫症	アカイエカ	リンパ系		急性期：夜間のmicrofilariaの検出慢性期：特有の症状を考慮	diethylcarbamazine & ivermectin
	Dirofilaria immitis	イヌ糸状虫		アカイエカ	なし	幼虫移行症→肺血管閉塞→胸部X線画像銭形陰影
	Gnathostoma spinigerum	有棘顎口虫	顎口虫症	ドジョウ、雷魚、ヘビの生食		消化管壁貫通→皮下移動による腫瘤や線状皮膚炎	移動性腫瘤、皮膚爬行疹雷魚やドジョウの生殖の問診免疫血清診断	なし
	Gnathostoma hispidum	剛棘顎口虫
	Gnathostoma doloresi	ドロレス顎口虫
	Gnathostoma nipponicum	日本顎口虫
	Anisakis simplex, larva	アニキサス幼虫	アニサキス症 (1)胃アニサキス症、 (2)腸アニサキス症、 (3)異所性アニサキス症	経口感染終宿主：クジラ、イルカ。中間宿主：オキアミ。待機宿主：サバ、ニシン、アジ、タラなど	胃や腸	(1)急激な上腹部痛"胃けいれん" (2)腹痛、急性虫垂炎、イレウス様。劇症型と緩和型がある (3)腹腔内の炎症性肉芽腫	胃内視鏡検査	内視鏡による虫体摘出
	Pseudoterranova decipiens	アニキサス幼虫	アニサキス症 (1)胃アニサキス症、 (2)腸アニサキス症、 (3)異所性アニサキス症	経口感染終宿主：クジラ、イルカ。中間宿主：オキアミ。待機宿主：サバ、ニシン、アジ、タラなど	胃や腸		胃内視鏡検査	内視鏡による虫体摘出
	Trichinella spiralis	旋毛虫	旋毛虫症	経口感染豚肉、クマ肉の生食		(1)成虫侵襲期：下痢、腹痛 (2)幼虫筋肉移行期：顔面浮腫、心筋障害など (3)幼虫被嚢期：全身浮腫、衰弱		急性期：ステロイド殺虫：mebendazole
			鞭虫症		盲腸	慢性下痢、腹痛、異食症、貧血	セロファン重層塗沫法、ホルマリンエーテル法	mebendazole
	Spirurin nematode larva	旋尾線虫	旋尾線虫幼虫	ホタルイカの生食	なし	皮膚爬行疹、イレウス様症状	予防：-30℃24時間。生食には-30℃4日間以上	摘出
吸虫類	Shistosoma japonicum	日本住血吸虫	日本住血吸虫症	糞便虫の虫卵→ミラシジウム→ ミヤイリガイ体内でセルカリア→ 人畜の皮膚より浸入→循環系→ 門脈に寄生	門脈	(1)潜伏期：侵入部の掻痒性皮膚炎。肺移行期：咳、発熱 (2)急性期：虫卵の門脈系寄生、産卵。住血吸虫性赤痢。 (3)慢性期：虫卵の肝、脳などの塞栓。肝硬変。脾腫、腹水	糞便虫の虫卵の検出。直腸粘膜層掻爬法、肝穿刺による組織内虫卵の検出。補助診断として免疫血清学的検査。	praziquantel
	Paragonimus westermani	ウェステルマン肺吸虫	肺吸虫症/肺ジストマ症	経口感染淡水産のカニ、イノシシ肉の生食	肺	痰、咳、胸痛、時に喀血	痰や便の虫卵検査、胸部写真、断層写真で明らかな虫嚢。免疫学血清検査
	Paragonimus miyazakii	宮崎肺吸虫	肺吸虫症/肺ジストマ症	経口感染淡水産のカニ、イノシシ肉の生食	肺	気胸、胸水貯留、膿胸、好酸球増加		praziquantel
	Clonorchis sinensis	肝吸虫	肝吸虫症/肝ジストマ症	経口感染虫卵→(マメタニシ:セルカリア)→ セルカリア→(魚:メタセルカリア)→ 摂取→(ヒト:成虫)→虫卵	胆管	胆汁流出障害による肝障害→肝硬変	糞便、胆汁(十二指腸ゾンデ法)。肝吸虫卵の検出。CT像。エコー検査。	praziquantel
			横川吸虫症	淡水魚(アユ、フナ、ウグイ、シラウオ)の生食	小腸粘膜	下痢、腹痛	糞便虫の虫卵	praziquantel
条虫類	Taeniarhynchus saginatus	無鉤条虫	腸管条虫症	経口感染。中間宿主：ウシ	小腸	無症状。下痢。広節裂頭条虫感染では悪性貧血。	糞便虫の虫卵と体節により診断	praziquantel。有鉤条虫の場合はガストログラフィン。有鉤条虫の駆虫の際、虫体を破壊しない →虫体の融解による嚢虫症
	Taenia solium	有鉤条虫		経口感染。中間宿主：ブタ
	Diphyllobothrium latum	広節裂頭条虫		経口感染。中間宿主：サケ、マス
		日本海裂頭条虫		経口感染。中間宿主：サケ
			腸管外条虫症
			有鉤嚢虫症	有鉤条虫の虫卵の経口摂取	皮下、筋肉内脳、脊髄、眼球	皮下、筋肉内：小指頭大の無症状腫瘤脳、脊髄、眼球：Jacksonてんかん。痙性麻痺など	皮下の虫嚢	外科的摘出。成虫寄生がなければ、praziquantel, albendazole + ステロイド
	Echinococcus granulosus	単包虫	包虫症/ エキノコックス症 (単包虫症)	終宿主：イヌ、キツネなど。中間宿主：ヒト、ブタ、野ネズミなど。終宿主の糞便虫の虫卵を中間宿主が接種して発症	肝、肺、まれに脳、腎、筋肉	肝寄生：肝部疼痛、満腹、時に黄疸、下肢浮腫肺寄生：胸部圧迫感、胸痛、咳、血痰、時に喀血	肝や肺の嚢胞形成から疑う。早期に診断に皮内反応→ CT、エコー→ 生検。免疫血清学的診断法	外科的切除。 albendazoleの長期投与
	Echinococcus multilocularis	多包虫	包虫症/ エキノコックス症 (多包虫症)	終宿主：イヌ、キツネなど。中間宿主：ヒト、ブタ、野ネズミなど。終宿主の糞便虫の虫卵を中間宿主が接種して発症	肝、肺、まれに脳、腎、筋肉	肝寄生：肝部疼痛、満腹、時に黄疸、下肢浮腫肺寄生：胸部圧迫感、胸痛、咳、血痰、時に喀血	肝や肺の嚢胞形成から疑う。早期に診断に皮内反応→ CT、エコー→ 生検。免疫血清学的診断法	外科的切除。 albendazoleの長期投与