Amebic dysentery - Amebic dysentery

Japanese: アメーバ赤痢 - アメーバせきり（英語表記）Amebic dysentery

What kind of infection is it?

It is an infectious disease of the large intestine caused by a protozoan called Entamoeba histolytica, and it is estimated that approximately 50 million people are infected and 40,000 to 100,000 people die each year worldwide. Cyst ( Noushi ) Infection occurs when food or drink contaminated with the virus is ingested. Asymptomatic infected individuals who excrete cysts are a more important source of infection than patients in the acute phase.

Compared to other parasitic infections, there are many cases of infection in Japan, so caution is required. 700-800 cases are reported annually, which is about 1.7 times higher than 4-5 years ago. There are only a few deaths each year. 80-90% of infected people have no history of traveling abroad, and most are homosexual men or intellectually disabled people. There are very few cases of food poisoning in Japan.

How symptoms manifest

Symptoms only appear in about 5-10% of infected people. bloating ( Kocho ) In typical cases, the patient will have dysentery symptoms such as lower abdominal pain during bowel movements. Exacerbation ( Zooac ) and Remission ( Relationship ) Repeat.

Intestines during exacerbation Perforation ( flash ) ( Hole ( hole ) In addition, about 5% of patients who develop colitis symptoms may develop extraintestinal infection. Sowing ( Hasshu ) (Pathogens are spread) in the liver, lungs, brain, etc. abscess ( Use ) This causes severe symptoms, with liver abscesses being the most common.

Testing and diagnosis

Diagnosis is made by microscopic identification of Entamoeba histolytica in stool or abscess fluid.

At the same time, the most reliable method is to directly prove the presence of Entamoeba histolytica by detecting the major antigenic protein of Entamoeba histolytica using an immunoenzyme antibody technique or by amplifying Entamoeba histolytica DNA using the PCR method.

It is also common to check whether the patient's blood contains antibodies against amebiasis, and tests can be requested from specialized research and testing institutions by general hospitals and clinics.

Treatment methods

Oral administration of metronidazole (Flagyl) or tinidazole is generally effective. In severe cases, intravenous administration of dehydroemetine is also used. In addition to metronidazole, diloxanide furoate is sometimes used to treat cyst carriers, and may be effective.

What to do if you notice an illness

Symptoms of enteritis may be mistaken for bacterial dysentery, ulcerative colitis, Crohn's disease, etc. Patients with amebic dysentery generally have a good overall condition, and often experience repeated exacerbations and remissions. Intestinal perforation and extraintestinal dissemination can be life-threatening, so if you notice symptoms, you should visit an internal medicine or infectious disease specialist.

Tomoyoshi Nozaki

Source: Houken “Sixth Edition Family Medicine Encyclopedia” Information about the Sixth Edition Family Medicine Encyclopedia

Japanese:

どんな感染症か

　赤痢アメーバという原虫による大腸の感染症で、世界で年間約5千万人の感染者、4～10万人の死亡者がいると推定されています。赤痢アメーバの嚢子(のうし)に汚染された飲食物を口からとることで感染します。急性期の患者さんよりも嚢子を排出する無症候性の感染者が感染源として重要です。

　ほかの寄生虫感染症に比べ、日本でも多くの感染が発症しているので注意が必要です。年間700～800人の届け出があり、4～5年前と比較すると約1.7倍増加しています。死亡例は年間数例です。感染した人の8～9割は海外渡航歴がなく、ほとんどの場合が男性同性愛者または知的障害者です。国内では食中毒として発生するケースはほとんどありません。

症状の現れ方

　感染しても症状が現れるのは5～10％程度です。粘血便、下痢、しぶり腹、鼓腸(こちょう)、排便時の下腹部痛などの赤痢症状を示します。典型的なケースではイチゴゼリー状の粘血便を排泄し、数日から数週間の間隔で増悪(ぞうあく)と寛解(かんかい)を繰り返します。

　増悪時は腸穿孔(せんこう)（孔(あな)があく）を起こしたり、腹膜炎を起こすこともあります。また、大腸炎症状を起こす患者さんのうち約5％で腸管外への播種(はしゅ)（病原体がばらまかれる）がみられます。肝臓・肺・脳などで膿瘍(のうよう)を形成し、重い症状を示します。このうち肝膿瘍が最も高い頻度でみられます。