AIM:To investigate the infection of Cyclospore cayetanensisin Anhui Province.METHODS:Identification of Cyclospore cayetanensis wasmade microscopically by finding the oocysts of Cyclosporecayetanensis in fecal smears taken from the infants,pupilsand adults with obstinate diarrhea,and immunocompromisedindividuals by using a auramine-phenol stain and modifiedacid-fast stain.Cellular immune function was detected withbiotin-streptavidin(BSA),and the specific antibody againstCyclospore cayetanensiswas detected with method of ELISA.RESULTS:(1)The positive rates of Cyclospore cayetanensisinfection in infants,pupils,infants and adults with obstinatediarrhea and with immunocompromised individuals weresignificantly different(P<0.01),with the rates of 0 %,0.50 %(1/200),5.62 %(10/178),and 9.38 %(3/32)respectively.(2)The infection rates of males and females were 2.61%(10/383)and 1.44 %(4/227)respectively,with no significantdifference(P<0.05).(3)The positive rates of populationwith oocysts in urban and rural areas were 0.92 %(3/325)and 3.86 %(11/285)respectively.(4)The positive rates ofCD_3~+,CD_4~+,CD_8~+and the ratio of CD_4~+/CD_8~+of individualswith and without oocysts were significantly different(P<0.05,P<0.01),and their values were(64.28±6.55)%,(43.55±5.80)%,(28.23±4.32)%,1.52±0.32 and(58.97±5.23)%,(39.26±4.93)%,(30.54±5.17)%,1.26±0.21,respectively.(5)Specific IgG,IgM and IgG+IgM in serum of the patientswith oocyst were significantly different(P<0.01)with thepositive rates of 63.41%(9/14),17.07 %(1/14)and 19.51%(4/14)respectively.CONCLUSION:Cyclospore cayetanensisinfection is presentin Anhui,China and it was confirmed to be a new pathogenassociated with children diarrhea,adults obstinate diarrheaand diarrhea in immunocompromised individuals.Amongall the infected individuals,adult obstinate diarrhea patientsand immunocompromised individuals are common.Fecesexamination of oocysts and serological examination of thespecific antibody will be of much help in the diagnosis ofCyclospore cayetanensis infection. AIM: To investigate the infection of Cyclospore cayetanensisin Anhui Province. METHODS: Identification of Cyclospore cayetanensis was made microscopically by finding the oocysts of Cyclosporecayetanensis in fecal smears taken from the infants, pupils and adults with obstinate diarrhea, and immunocompromisedindividuals by using a auramine-phenol stain and modifiedacid-fast stain. Cellular immune function was detected withbiotin-streptavidin (BSA), and the specific antibody againstCyclospore cayetanensiswas detected with method of ELISA.RESULTS: (1) The positive rates of Cyclospore cayetanensisinfection in infants, pupils, infants and adults with obstinatediarrhea and with immunocompromised individuals weresignificantly different (P <0.01), with the rates of 0%, 0.50% (1/200), 5.62% (10/178), and 9.38% (3/32) respectively. Rates of males and females were 2.61% (10/383) and 1.44% (4/227) respectively, with no significant difference (P <0.05). (3) The positive rates of population with oocysts in urban a nd rural areas were 0.92% (3/325) and 3.86% (11/285) respectively. (4) The positive rates of CD_3 ~ +, CD_4 ~ +, CD_8 ~ + and the ratio of CD_4 ~ + / CD_8 ~ + of (64.28 ± 6.55)%, (43.55 ± 5.80)%, (28.23 ± 4.32)%, 1.52 ± 0.32 and (58.97 ± 5.23), respectively, with or without oocysts were significantly different (P <0.05, ), (39.26 ± 4.93)%, (30.54 ± 5.17)%, 1.26 ± 0.21, respectively. (5) Specific IgG, IgM and IgG + IgM in serum with the patients with oocyst were significantly different (P <0.01) Rates of 63.41% (9/14), 17.07% (1/14) and 19.51% (4/14) respectively. CONCLUSION: Cyclospore cayetanensis infection is present in Anhui, China and it was confirmed to be new pathogenassociated with children diarrhea, adults obstinate diarrhea and diarrhea in immunocompromised individuals. Amongall the infected individuals, adult obstinate diarrhea patients and immunocompromised individuals are common. Fecesexamination of oocysts and serological examination of thespecific antibody will be of much help in the diagnosis ofCyclospore cayetanensis infection.