患者，男，87岁，农民，河南永城人。患者自述于2023年6月25日无明显诱因出现纳差、食欲下降，伴有腹泻（4~5次/d）和低热（体温37.5 ℃）。就诊于当地社区医院，未予详细检查，输液（具体药物不详）治疗后无好转，于7月5日转诊至河南省永城市中心医院。患者长期务农，家中饲养猫、犬等动物，无猪饲养史及密切接触史，无猪粪施肥，无饮用生水史。入院查体：体型消瘦，心肺听诊无明显异常，腹部平软，未见胃肠型及蠕动波，未见腹部静脉曲张，肝脾肋下未触及，下腹部有压痛，其余部位无压痛及反跳痛，移动性浊音阴性，肠鸣音活跃，未闻及气过水声。血常规示：白细胞计数11.9 × 10⁹/L，红细胞计数4.11 × 10¹²/L，血小板计数358 × 10⁹/L，血红蛋白119 g/L，血钾3.13 mmol/L，肝功能白蛋白32.5 g/L。粪常规示：墨绿色稀便，隐血试验阳性，未见红细胞、白细胞，未检出寄生虫或虫卵，粪样培养无异常。行全腹部CT平扫+增强，示胆囊体积增大，肝门区胆管、胆总管及胰管稍扩张，胃底近贲门处胃壁稍增厚，直肠、乙状结肠肠壁弥漫性增厚、水肿。予以补液、维持水电解质平衡、纠正电解质紊乱治疗，同时口服小檗碱片（每次0.1 g，3次/d）、蒙脱石散（每次3 g，3次/d）、双歧杆菌（每次1 g，3次/d，与蒙脱石散间隔2 h服用），患者排便次数逐渐减少，逐渐转为黄色软便。7月11、12日粪样经显微镜下观察，均检测到疑似结肠小袋纤毛虫包囊，经永城市疾病预防控制中心会诊确认为结肠小袋纤毛虫包囊。调整为口服小檗碱（每次0.1 g，3次/d）和甲硝唑片（每次0.2 g，2次/d），继续予营养支持治疗。7月13日，患者排便已转为每日1次，黄色软便，镜检未见寄生虫。7月18日，患者经综合治疗后痊愈出院，随访观察显示预后良好。

The patient was an 87-year-old male farmer from Yongcheng, Henan. He reported having nausea and decreased appetite without obvious causes on June 25th, 2023, accompanied by diarrhea (4-5 times/d) and low-grade fever (body temperature of 37.5 ℃). He was treated at a local community hospital without detailed examinations and showed no improvement after receiving infusions of unknown drugs. Due to a referral, he was admitted to the Yongcheng Central Hospital on July 5th. The patient has been undertaking farming for a long time, and animals such as cats and dogs are bred in his home. He has no history of breeding pigs or close contact, no history of applying pig manure, and no history of drinking unboiled water. On admission, physical examination showed a thin body type, no apparent abnormalities in heart and lung auscultation, a soft and flat abdomen, no gastrointestinal waves or peristalsis, no varicose veins in the abdomen, no liver or spleen felt under the ribs, tenderness in the lower abdomen, no tenderness or rebound tenderness in other parts, negative mobile cloudy urine, active bowel sounds, and no audible gas-water sound. The blood routine test showed a white blood cell count of 11.9 × 10⁹/L, a red blood cell count of 4.11 × 10¹²/L, a platelet count of 358 × 10⁹/L, a hemoglobin of 119 g/L, a blood potassium of 3.13 mmol/L, and an albumin of 32.5 g/L in the liver function test. The stool routine test showed a dark green loose stool, a positive occult blood test, no red blood cells or white blood cells, no parasitic eggs detected, and no abnormalities in the fecal culture. A plain and enhancement scan of the entire abdomen was performed, which showed an increased volume of the gallbladder, slightly dilated bile ducts, common bile duct, and pancreatic duct in the hepatic portal area, slightly thickened gastric wall near the cardia, and diffuse thickening and edema of the intestinal walls in the rectum and sigmoid colon. The patient was treated for rehydration and correction of electrolyte imbalance. Simultaneously, oral berberine tablets were given (0.1 g each time, 3 times/d), smecta powder (3 g each time, 3 times/d), and bifidobacterium (1 g each time, 3 times/d, taken 2 h apart from smecta powder). The frequency of the patient’s bowel movements gradually decreased and gradually turned to soft and yellow stools. On July 11st and 12th, the stool samples were microscopically observed and both tested positive for suspected Balantidium coli. After consultation with the Yongcheng Center for Disease Control and Prevention, it was confirmed to be B. coli. The patient was adjusted to oral berberine (0.1 g each time, 3 times/d) and metronidazole tablets (0.2 g each time, 2 times/d), and continued to receive nutritional support treatment. On July 13th, the patient’s bowel movements had converted to daily, yellow and soft stools, and no parasites were found under microscopy. On July 18th, the patient was discharged from the hospital after comprehensive treatment, and follow-up observations showed a good prognosis.