Molecular epidemiological related research on Cryptosporidium infection in children under 5 years old with diarrhea in a hospital of Inner Mongolia Autonomous Region

doi:10.20199/j.issn.1672-2302.2026.01.006

Abstract

Abstract:

Objective To understand the molecular epidemiological characteristics of Cryptosporidium infection in children 5 years old and under with diarrhea in a hospital in Inner Mongolia Autonomous Region for a reference in prevention and control of this infection in the local area. Methods The fecal samples were obtained from children 5 years old and under with diarrhea who were treated at the Inner Mongolia Autonomous Region Maternal and Child Health Hospital during September 2021 and August 2022. The 18S rRNA gene fragment of Cryptosporidium was amplified using nested PCR to investigate the infection status of this protozoan parasite. Homology analysis was performed based on the 18S rRNA gene sequence and a phylogenetic tree for the species identified was constructed. The gene subtypes were further identified based on the gp60 gene locus. Results A total of 1 292 fecal samples were collected from the diarrheic children, in which 156 samples were positive for Cryptosporidium 18S rRNA gene sequencing, with a positive rate of 12.07%. The positive rate was 13.37% (92/688) for boys and 10.60% (64/604) for girls. The difference was insignificant (χ²=2.335, P>0.05). Children aged 1-3 years had the highest positive rate (15.70%，81/516), the difference was statistically significant between groups (χ²=12.620, P<0.05). The positive rate was higher in the children with diarrhea living in the suburban and rural counties than that of those from urban areas (15.66%, 62/396 vs. 10.49%, 94/896), and the difference was statistically significant (χ²=6.902, P<0.05). Positive cases were detected in all months, with December having the highest positivity rate (17.81%, 13/73). All positive samples were identified as Cryptosporidium parvum through homology analysis, and the phylogenetic tree showed clustering with reference strains of Cryptosporidium parvum in the same branch. Based on the gp60 gene, five subtypes were detected, including ⅡdA23G3, ⅡdA24G3, ⅡdA24G4, ⅡdA25G3, and ⅡdA25G4, with ⅡdA25G3 being the dominant subtype (42.95%, 67/156). The phylogenetic tree revealed that these five subtypes formed independent evolutionary branches and clustered with known Ⅱd subtypes of Cryptosporidium parvum in the same branch. Conclusion The prevalence of Cryptosporidium infection among local children with diarrhea is relatively high. Children aged 3 years and under are the key target population, and suburban counties are the important regions of concern. The prevalent species is Cryptosporidium parvum, with ⅡdA25G3 being the dominant subtype.

Key words: Cryptosporidium, Children, Diarrhea, Molecular epidemiology, Inner Mongolia Autonomous Region

CLC Number:

R725.7

LIANG Ru, ZHANG Liang, GUO Wenhui, XUE Xinyu, LI Ruifeng. Molecular epidemiological related research on Cryptosporidium infection in children under 5 years old with diarrhea in a hospital of Inner Mongolia Autonomous Region[J]. Journal of Tropical Diseases and Parasitology, 2026, 24(1): 30-35.

Figures/Tables 5

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分布特征	检测数（例）	阳性数（例）	阳性率（%）	分布特征	检测数（例）	阳性数（例）	阳性率（%）
性别				土默特左旗	71	12	16.90
男	688	92	13.37	清水河县	63	8	12.70
女	604	64	10.60	检出月份
年龄（岁）				1	72	12	16.67
<1	668	69	10.33	2	60	9	15.00
1~3	516	81	15.70	3	97	11	11.34
4~5	108	6	5.56	4	110	11	10.00
居住地				5	115	11	9.57
赛罕区	277	29	10.47	6	148	14	9.46
回民区	209	25	11.97	7	132	16	12.12
新城区	234	23	9.83	8	141	16	11.35
玉泉区	176	17	9.66	9	118	13	11.02
武川县	104	15	14.42	10	116	16	13.79
和林格尔县	76	14	18.42	11	110	14	12.73
托克托县	82	13	15.85	12	73	13	17.81