Mapping Prevalence, Diagnostics, and Evidence Gaps of Cryptosporidium in Southeast Asia Across Human, Animal, and Environmental Domains: Protocol for a One Health Scoping Review.

Background: Cryptosporidium is a waterborne and zoonotic protozoan parasite that causes cryptosporidiosis, a diarrheal disease that disproportionately affects young children and immunocompromised individuals in low- and middle-income settings. In Southeast Asia, ecological diversity, agricultural intensification, and uneven sanitation infrastructure create overlapping transmission pathways across human, animal, and environmental domains. Despite a growing body of regional literature, the structure of the evidence base and its utility for surveillance and control have not been comprehensively evaluated using an integrated One Health lens. Objective: This protocol outlines the methodology for a scoping review mapping the published literature on Cryptosporidium in Southeast Asia, characterizing the distribution of evidence on prevalence, diagnostic methods, species and genotype diversity, and environmental, food-related, and socioeconomic determinants of transmission across human, animal, and environmental domains. Methods: The review follows the Arksey and O'Malley framework, refined by Levac and colleagues and the Joanna Briggs Institute, and is reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR). Five databases were searched from inception through September 30, 2024: PubMed, Embase, CABI Digital Library, Cochrane Library, and Index Medicus for the South-East Asia Region (IMSEAR), supplemented by backward citation tracking and targeted searches of organizational websites. Studies were included if they reported primary data on Cryptosporidium in human, animal, or environmental samples collected from one or more of the eleven Southeast Asian countries and addressed prevalence, diagnostic methods, or transmission risk factors. Reviews, editorials, letters, conference abstracts, and non-English publications were excluded. No formal risk-of-bias assessment was conducted, consistent with scoping review methodology. Data were organized thematically and synthesized descriptively, with findings presented across One Health domains using tables, figures, and maps generated in RStudio (version 2023.09.1+494). Results: Database searches retrieved 889 records before deduplication. After removing 177 duplicates, 711 unique records underwent title and abstract screening. Of 333 full-text articles assessed for eligibility, 176 studies were included in the final synthesis, representing nine of eleven Southeast Asian countries and spanning 1985 to 2024. Data extraction and analysis are complete. The manuscript reporting the full findings is being prepared for submission to a peer-reviewed journal. Conclusions: This scoping review provides a comprehensive cross-domain mapping of evidence on Cryptosporidium in Southeast Asia. The findings are expected to identify structural gaps in the regional evidence base, characterize diagnostic heterogeneity and its implications for surveillance utility, and support the development of integrated One Health surveillance strategies in the region.