糞小桿線蟲是一種可寄生在人體腸胃道的寄生蟲，常見於熱帶與亞熱帶地區，主要經由接觸有糞便汙染的環境而感染。感染性幼蟲穿透皮膚後，隨著血液循環系 統進入心臟、肺臟，並上行至咽喉處再經由人體吞嚥動作進入腸胃道。許多患者於感染初期不會出現症狀，且於臨床上並無明顯特異性之症狀，其腸胃道的症狀包括 腹瀉、嘔吐、食慾不振、腹脹、腹痛等，若遇患者免疫力低下，亦可能造成全身性感染。臨床診斷主要利用糞便鏡檢有無蟲卵或檢查十二指腸液中有無桿狀幼蟲，然 而由於糞便中蟲體較少或間歇性出現，所以此方法的敏感度不高。本文報告一名64歲務農女性，因腸胃不適至本院就診，初步糞便鏡檢未發現寄生蟲感染，經由胃腸 鏡採樣的檢體送病理切片檢查後確診有糞小桿線蟲感染。

Strongyloides stercoralis, one of the intestinal nematode species, is soiltransmitted and endemic in tropical and subtropical climates. Its infective larvae penetrates the skin, enters the venous system, travels to the heart and lung,migrates up to the esophagus, is swallowed, and finally reaches the small intestine. Manifestations of infection can be asymptomatic or clinically inapparent.Gastrointestinal symptoms of strongyloidiasis include diarrhea, nausea, vomiting, anorexia, abdominal bloating and pain. In immunocompromised patients,hyperinfection or disseminated strongyloidiasis may occur. Clinical diagnosis of strongyloides stercoralis is usually made by stool examination to detect the rhabditiform larvae or eggs. However, stool examination is insensitive due to the low parasite load and the irregular larval output. We report a 64-year-old woman working in farming with a chief complaint of gastrointestinal discomfort. Infection of strongyloides stercoralis was not detected by stool examination the first time. Strongyloidiasis was confirmed by pathological diagnosis, and the specimens were taken by colonoscopic biopsy.