血吸虫病（英语：schistosomiasis、bilharzia、snail fever、Katayama fever）又称裂体虫病、曼森氏病，是一个由血吸虫类的寄生虫所导致之疾病。它有可能感染尿道或消化系统。症状包括腹痛、下痢、血便、或血尿。在受到长期感染的人身上，有可能导致肝脏受损、肾衰竭、不孕或膀胱癌。在儿童身上，可能造成发育不良和学习障碍。

此疾病的传播途径为接触到含寄生虫的水源。寄生虫由受到感染的淡水蜗牛发布。此疾病在开发中国家的小孩身上最为常见，因为他们有较高的机率在戏水过程中接触到受污染的水源。其他的高危险群包括农夫、渔夫以及日常水源受污染者。血吸虫病属于蠕虫感染的一种，诊断依据为在患者的尿液或粪便中发现寄生虫卵。亦可经由血液中发现针对此疾病的抗体而确诊。

Schistosomiasis, also known as snail fever, is a disease caused by parasitic flatworms called schistosomes. The urinary tract or the intestines may be infected. Signs and symptoms may include abdominal pain, diarrhea, bloody stool, or blood in the urine. Those who have been infected a long time may experience liver damage, kidney failure, infertility, or bladder cancer. In children, it may cause poor growth and learning difficulty.