日本人に発症したビルハルツ住血吸虫症の1例

Abstract

25歳男.主訴は肉眼的血尿.患者は1999～2001年にアフリカ・中南米・東アジアを旅行し, アフリカ滞在中の1999年10月にはマラウィー湖でダイビングを行った経験があった.血中好酸球増多を認め, 活動性の寄生虫感染症を疑われた.検尿にて軽度の血膿尿があり, 1回排尿量全量の沈渣ではビルハルツ住血吸虫に特有な突起(terminal spine)を持つ虫卵を認めた.尿中および血中に好酸球を多数認め, また, 血中抗マンソン住血吸虫虫卵抗体価は0.6であった.内視鏡所見で三角部から後壁にかけて黄白色の結節(bilharzial tubercle)を多数認め, 同部を生検した.病理組織学的所見では膀胱粘膜下に一部石灰化を伴う虫卵を多数認めた.虫卵の周囲には著明な好酸球浸潤, 肉芽腫の形成を認めた.上皮の異型はみられなかった.診断後, praziquantel 40mg/kg/dayを2日間投与した.投与後1ヵ月を経たが, 尿中より虫卵が検出されているため再び同量のpraziquantelを投与した.その後尿中虫卵は陰性化し, praziquantel投与後半年を経過するが, 血尿や膀胱刺激症状を認めず経過は良好である

Bilharziasis is an endemic disease distributed mostly in African countries and the Middle East, and causes severe disturbances of urinary tract secondarily. Although it used to be a very rare disease in Japan, modern human mobility and jet travel have brought this tropical disease into our country far from endemic areas. A 25-year-old Japanese male presented to our hospital with macroscopic hematuria. He had an experience of traveling to Malawi two years before. Cystourethroscopy demonstrated so-called 'bilharzial tubercles', many yellowish specks of mucosa at the posterior wall and dome of the bladder. The diagnosis of bilharziasis was made by detection of Schistosoma haematobium eggs in urine and histological specimen obtained by transurethral biopsy. In this case, radiographic and pathological examinations revealed neither obstructive uropathy nor urothelial malignancy. He was treated with praziquantel, and the disease is under good control.