出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/06/13 19:32:17」(JST)
| Gnathostoma spinigerum | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Nematoda |
| Class: | Secernentea |
| Order: | Spirurida |
| Family: | Gnathostomatidae |
| Genus: | Gnathostoma |
| Species: | G. spinigerum |
| Binomial name | |
| Gnathostoma spinigerum Levinsen, 1889 |
|
Gnathostoma spinigerum is a parasitic nematode that causes gnathostomiasis in humans, also known as its clinical manifestations are creeping eruption, larva migrans, Yangtze edema, Choko-Fuschu Tua chid and wandering swelling. Gnathostomiasis in animals can be serious, and even fatal. The first described case of gnathostomiasis was in a young tiger that died in the London Zoo in 1835. The larval nematode is acquired by eating raw or undercooked fish and meat.
G. spinigerum has a multi-host life history. The eggs hatch in fresh water and the larvae are eaten by water fleas of the genus Cyclops. The water fleas are in turn eaten by small fish. Eventually, the larvae end up in the stomachs of carnivores, usually cats and dogs. The larva bores through the stomach wall and migrates around in the host's body for about three months before returning to the stomach and attaching itself in the gastric mucosa. It then takes another six months to mature. The eggs are carried in the host's feces, and if they reach fresh water the cycle begins again. As humans are not a normal host for the larva, they do not mature in humans, but can cause various degrees of damage, depending on where the larva wanders in the body.
This species grows to a length of 11 to 54 mm (0.43 to 2.13 in).
Species within the genus Gnathostoma are recognized by a bulbous head with a pair of lateral lips surrounding a mouth on the longitudinal axis. The cephalic region is covered by transverse rows of cuticular spines. Internally, the head is divided into four glandular cervical sacs that attach near the esophagus, as well as four hollow spaces called ballonets, each being continuous with a cervical sac via a central canal.[1]
The body is typically pink and is also covered anteriorly with circles of flat spines, which become sparser and single-tipped further toward the end. Behind a bare region that constitutes roughly half of the body length, many small spines can be found on the posterior tip. the four species gnathostomiasis--G. doloresi, G. hispidum, G. nipponicum, and G. spinigerum can cause human –these species are differences in these external appearance and third larvae stage which is helpful for identification.[2]
As a nematode, Gnathostoma spinigerum has cylindrical, a cuticle layer with three main outer layers made of collagen and other compounds. The outer layers are non-cellular and are secreted by the epidermis. The cuticle layer protects the nematodes so they can invade the digestive tracts of animals.[3]
Nematodes have longitudinal muscles along the body wall. The muscles are obliquely arranged in bands. Dorsal, ventral and longitudinal nerve cords are connected to the main body of the muscle. As a nematode in the group Secernentea, Gnathostoma have specialized tubular excretory system with three canals. The canals are arranged to form an H.[3]
On average, female worms are larger than males by an estimated 4 mm in length and 0.65 mm in width. Respectively, their size ranges from 11 to 54 mm and 11 to 31 mm long. Females are different from males in that they possess only two large papillae around their slightly rounded posterior ends. From the side view, the dorsal outline is rounded, whereas the ventral side appears flat. Males have eight caudal papillae encompassing the anus on their bluntly rounded ends. Characteristic of males is the presence of blunt spicules that play the important reproductive role of holding open the vagina during sperm transfer. These male copulatory organs measure 1.1 mm and 0.4 mm long.[4]
Just before molting into an adult, fourth-stage larvae have eight transverse rows of cephalic hooklets. At this point of development males can easily be differentiated from females based on identifiable sexual organs. Advanced third-stage larvae bear four rows of hooklets on their head bulbs and measure 3 to 4 mm in length and 0.3 to 0.4 mm wide. The distinctive swollen head morphology, in addition to the four rows of hooklets, already becomes apparent in second-stage larvae. Eggs have a polar cap at only one end and are laid un-embryonated within pitted shells. Their dimensions are 65-70 µm by 38-40 µm [2]
Although Gnathostoma spinigerum are considered endemic to Thailand, they are also found in many other countries of Southeast Asia. These nematode parasites have also been reported to be found in Japan, Australia, United States, and Mexico. However, the incidence of infection is rarer outside the Asian continent [5]
Gnathostoma spinigerum normally could be found in wet tropical environments. Larvae can infect many classes of animals. Canine and feline species, and possibly pigs, are determined as c the definitive hosts. In Japan, freshwater fishes, Ophicephalus argus and O. tadianus, are the most important vectors of human gnathostomiasis. In addition to freshwater fishes, domestic duck, Anas platyrhynchus and the domestic chicken Gallus gallus domesticus carry the parasite in Thailand.[6]
In a study done in Siam, researchers have proposed a method of prevention of gnathostomiasis. It states that humans can become infected via eating fresh water fish. For example, a popular dish serving fermented fresh water fish is popular among the women of Siam, which may explain their higher incidence of the infection. In order to avoid or kill the infective larva living in fish muscle, one must boil the first for a minimum of five minutes, placed in a solution of vinegar and 4% acetic acid for a period of 5.5 hours, or just to avoid raw or undercooked fish, always being sure to cook fresh water fish thoroughly [7]
Laboratory testing on mice treated once or twice daily with albendazole were shown to have a significant reduction in worm count when compared to the untreated mice group. The effective dosage at which albendazole is much effective is 90 mg/kb twice a day for 21 straight days. On the other hand, there are other antihelminthic drugs available such as bithionol, thiabendazole, metronidazole, and others, that did not reveal any significant therapeutic effects in experimentally G. spinigerum infected [3]
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| リンク元 | 「蠕虫」「有棘顎口虫」 |
| 関連記事 | 「Gnathostoma」 |
| 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 | |||||||
| 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 | |||||||
| 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 | ||||||||
| 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 |
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| Paragonimus miyazakii | 宮崎肺吸虫 | 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) | ||||||