Molecular prevalence and diagnostic gene targets of Anaplasma, Babesia, Theileria, and Trypanosoma in cattle and buffaloes across Southeast Asia (2015-2025): A systematic review and meta-analysis.

Abstract

Background and aim: Hemoparasitic infections caused by Anaplasma, Babesia, Theileria, and Trypanosoma adversely affect cattle and buffalo health, resulting in economic losses and reduced livestock productivity in Southeast Asia. Although numerous molecular epidemiological studies have been conducted in individual countries, a comprehensive regional synthesis of polymerase chain reaction (PCR)-confirmed prevalence and molecular diagnostic targets has been lacking. This study aimed to estimate the pooled molecular prevalence of major hemoparasites in cattle and buffaloes across Southeast Asia, summarize the PCR target genes used for their detection, and investigate the effects of geographical region and host species on prevalence.

Materials and methods: A systematic review and meta-analysis were conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed, ScienceDirect, and Scopus were searched for studies published between 2015 and December 31, 2025. Cross-sectional studies conducted in Southeast Asia that used PCR-based methods and reported extractable prevalence data were included. Pooled prevalence estimates were calculated using random-effects meta-analysis. Heterogeneity was assessed using Cochran's Q test and the I² statistic, whereas meta-regression was performed to evaluate the influence of geographical region (mainland versus maritime Southeast Asia) and host species. Publication bias was assessed for Babesia spp.

Results: Twenty-two cross-sectional studies involving 5,789 cattle and 901 buffaloes met the inclusion criteria. The pooled prevalence was 12% (95% confidence interval [CI]: 3%-38%) for Anaplasma spp., 18% (95% CI: 11%-28%) for Babesia spp., 11% (95% CI: 3%-35%) for Theileria spp., and 11% (95% CI: 4%-28%) for Trypanosoma evansi. Species-specific pooled prevalences were 5% for Anaplasma marginale, 10% for Babesia bigemina, 9% for Babesia bovis, and 10% for Theileria orientalis. Significant between-study heterogeneity was observed across all analyses. Meta-regression identified a significantly higher prevalence of B. bovis in maritime than mainland Southeast Asia (p = 0.0048), whereas no significant regional or host species effects were detected for the remaining hemoparasites. The review also compiled the principal PCR target genes used for molecular diagnosis, including 16S rRNA, groEL, MSP4, RAP-1a, AMA-1, SBP-2, SBP-4, MSA, MPSP, RoTat 1.2 VSG, ITS1, ITS2, and satellite DNA.

Conclusion: Major bovine hemoparasites remain widely distributed across Southeast Asia, highlighting the need for strengthened molecular surveillance and standardized diagnostic approaches. This study provides the first comprehensive regional synthesis of PCR-confirmed prevalence and molecular diagnostic targets for major hemoparasites in cattle and buffaloes, offering valuable evidence to support veterinary diagnostics, surveillance programs, and disease control strategies based on a One Health approach.