寄生虫疾患の病態と画像診断

Pathophysiology and Imaging Diagnosis of Parasitic Diseases

要旨●アニサキス症の感染源として，さまざまな海産魚が報告されている．治療法としては内視鏡での摘出の他，アミドトリゾ酸ナトリウムメグルミン液（ガストログラフイン®）の経口投与や強力ネオミノファーゲンシー®（SNMC），プレドニン®の投与が有効との報告がある．クドア症はヒラメに寄生するナナホシクドアによる食中毒であり，ヒラメの生食と類症者の存在の問診が診断に重要な情報である．サルコシスティスは胞子虫類に分類され，牛肉，馬肉，鹿肉などの生食歴が重要な情報となる．鞭虫症は土壌伝播性の人畜共通の寄生虫疾患であり，主に熱帯および亜熱帯地域で問題となるが，近年国内における症例報告が散見されている．日本海裂頭条虫症はサクラマス，カラフトマス，シロザケなどのサケ属の魚の生食により感染する．治療としてはアミドトリゾ酸やプラジカンテル（ビルトリシド®）の内服が挙げられる．旋尾線虫幼虫type X感染症はCrassicauda giliakianaの幼虫移行症であり，ホタルイカがヒトへの感染源として重要視されている．急性腹症として発症し，ほとんどの症例では保存的治療で軽快する．ジアルジア症は，ランブル鞭毛虫による寄生虫疾患で，糞便中に排出された囊子の経口摂取により感染する．臨床症状は下痢，腹痛，悪心・嘔吐が多い．メトロニダゾール750mg/day内服（5〜7日間）が有効である．鉤頭虫症はトドを終宿主とするCorynosoma villosumの小腸・大腸壁への刺入が原因である．ニシンの生食が感染源の一つと考えられ，ホッケやヒラメなどその他の沿岸魚類にも注意が必要である．治療法は内視鏡検査での摘出が報告されているのみである．

　Anisakiasis is known to be transmitted by a variety of marine fishes. In addition to endoscopic removal, oral sodium meglumine amidotrizoate（Gastrografinsa®）and intravascular Stronger Neo-Minophagen C, and prednisone have been identified as effective treatment options. Kudoosis is a type of food poisoning caused by Kudoa septempunctata, a myxosporean parasite of the Japanese flounder. A history of raw consumption of the flounder and the presence of other patients with similar symptoms are important diagnostic clues. Sarcosystosis is also a type of food poisoning caused by Sarcocystis spp., which are classified as sporozoan parasites. A history of eating raw meat such as beef, horsemeat, or venison is important diagnostic information. Trichuriasis, which is caused by a soil-transmitted zoonotic parasite known as Trichuris trichiura, is mainly a problem in tropical and subtropical regions ; however, cases have been reported in Japan in recent years. Diphyllobothriasis due to infection with Dibothriocephalus nihonkaiensis is transmitted by eating raw Oncorhynchus species such as Masu salmon, Pink salmon, and Chum salmon. Its treatment options include oral sodium amidotrizoate meglumine solution（Gastrografin®）or praziquantel（Viltricid®）. Human infection with Spirurina type X larvae is currently recognized as the larval migration of Crassicauda giliakiana. The firefly squid is considered an important source of infection. The disease presents as acute abdominal symptoms that, in most cases, improve with conservative treatment. Giardiasis is a parasitic disease caused by Giardia lamblia, which is transmitted by the oral ingestion of cysts excreted in feces. Its clinical manifestations include diarrhea, abdominal pain, nausea, and vomiting. Oral administration of 750mg/day of metronidazole（for 5-7days）is effective. Corynosomiasis is caused by the acanthocephalan parasite known as Corynosoma villosum, which uses the Steller sea lion as a definitive host and penetrates the small and large intestinal walls. The consumption of raw herring is thought to be one of the sources of infection, and other coastal fishes such as the Atka mackerel and Japanese flounder also deserve attention. The only treatment reported so far is endoscopic removal.