A One Health Molecular Investigation and Exploratory Epidemiological Analysis of Cryptosporidium spp. in A Shared Human‐Animal Ecosystem

INTRODUCTION: Cryptosporidium spp. are enteric protozoan parasites of public health importance, particularly in low-resource settings where humans, animals and environmental water sources frequently interact. This study investigated the prevalence, molecular diversity and environmental exposure-related variables in relation to Cryptosporidium infection in a rural community. METHODS: A cross-sectional study was conducted using 180 faecal samples collected from humans, cattle, chickens, fish, cats, dogs, and ducks. Speciation and subtyping were determined through PCR amplification and sequencing of the 18S rRNA and gp60 genes. Epidemiological and environmental data were collected, and univariable analyses were conducted. An exploratory multivariable logistic regression model was subsequently performed for the human subset. RESULTS: The overall prevalence of Cryptosporidium infection was 9.40%, with the highest rates observed in humans (14.8%) and cattle (13.5%). Molecular characterisation identified C. hominis, C. parvum, C. bovis and C. felis. Among humans, C. hominis was the predominant, whereas C. parvum was also detected, including mixed infections. gp60 analysis identified multiple subtype families, including Ia, Ib, IIa, IIc and IId. Phylogenetic analysis demonstrated close genetic relationships between Bangladeshi isolates and previously reported reference strains from South Asia and the Middle East. Higher odds of Cryptosporidium infection were observed among individuals reporting river bathing and consumption of untreated water, whereas lower odds were observed among those reporting regular handwashing. No statistically significant associations were identified between evaluated environmental variables and infection among non-human hosts. CONCLUSION: The study demonstrated the circulation of multiple Cryptosporidium species and subtype families within a shared human-animal ecosystem. The contaminated surface water and inadequate hygiene practices may represent important environmental exposure interfaces for Cryptosporidium infection in the study area. However, given the cross-sectional design and limited number of positive cases, the epidemiological findings should be interpreted as exploratory associations rather than definitive transmission pathways. Further longitudinal One Health investigations are needed.