In acute gastroenteritis (GE), identification of the infectious agent is important for patient management and surveillance. The prevalence of GE caused by protozoa may be underestimated in Swedish patients. The purpose was to compare the prevalence of E. histolytica, Cryptosporidium spp., G. intestinalis, and C. cayetanensis in samples from patients where the clinician had requested testing for gastrointestinal parasites only (n = 758) to where testing for bacterial GE only (n = 803) or where both parasite and bacterial testing (n = 1259) was requested and a healthy control group (n = 197). This prospective cohort study was conducted in Region Jönköping County, Sweden (October 2018–March 2019). Fecal samples were analyzed with microscopy and real-time PCR. Cryptosporidium spp. was detected in 16 patients in the bacterial GE group and in 13 in the both bacterial and parasite group; no cases were detected in the group were only parasite infection was suspected. C. cayetanensis was detected in two patients in the bacterial GE group. One case of E. histolytica was detected in the bacterial group and one in the both bacterial and parasite group. G. intestinalis was detected in 14 patients in the parasite only group, 12 in the both parasite and bacterial group, three in the bacterial GE group, and one in the control group. Diarrhea caused by protozoa, especially Cryptosporidium was under–recognized by clinicians and is likely more common than hitherto estimated in Sweden. A more symptom-based diagnostic algorithm may increase detection and knowledge about protozoan infections.

在急性胃肠炎（GE）中，识别传染原对于患者的管理和监测很重要。在瑞典患者中，可能会低估了由原生动物引起的GE患病率。目的是比较临床医生仅要求检测胃肠道寄生虫（n  = 758）的患者样本中的溶组织性大肠杆菌，隐孢子虫，肠道小肠杆菌和cayetanensis的患病率，以及仅检测细菌GE的患病率（n  = 803）或要求同时进行寄生虫和细菌检测（n  = 1259）和健康对照组（n = 197）。这项前瞻性队列研究在瑞典延雪平地区（2018年10月至2019年3月）进行。用显微镜和实时PCR分析粪便样品。隐孢子虫属。在细菌GE组中有16例患者被检出，在细菌和寄生虫组中13例中被检出；在该组中未发现任何病例，仅怀疑是寄生虫感染。在细菌GE组中的两名患者中检测到了C. cayetanensis。在细菌组中检出1例溶组织性大肠杆菌，在细菌和寄生虫组中均检出1例。肠球菌仅寄生虫组中有14例患者被检出，寄生虫和细菌组中有12例被检出，细菌GE组中有3例，对照组中有1例。由原生动物引起的腹泻，特别是隐孢子虫引起的腹泻，临床医生对这种现象的认识不足，而且可能比迄今在瑞典估计的更为普遍。基于症状的诊断算法可能会增加对原生动物感染的检测和了解。