作者单位:King Saud Univ, Colorectal Res Ctr, Dept Surg, Riyadh 11472, Saudi Arabia[1]Univ Calif San Francisco, Ctr Discovery & Innovat Parasit Dis, San Francisco, CA 94158 USA[2]King Saud Univ, Dept Pathol, Riyadh 11472, Saudi Arabia[3]Univ Ottawa, Div Gen Surg, Ottawa Hosp, Ottawa, ON K1H 8L6, Canada[4]