A systematic review of peste des petits ruminants in Bangladesh: Epidemiology, diagnostics, risk factors, vaccination, and gaps toward eradication.

Background and Aim: Peste des petits ruminants (PPR) is a highly contagious transboundary viral disease that severely impacts small ruminant production systems, particularly in low- and middle-income countries. In Bangladesh, where goats and sheep are critical to rural livelihoods, PPR remains endemic and poses substantial economic and food security challenges. This systematic review aimed to synthesize current evidence on the epidemiology, diagnostic approaches, risk factors, vaccine performance, and existing knowledge gaps to support national and global eradication efforts. Materials and Methods: A systematic review was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. A total of 930 records were identified through PubMed and Google Scholar, of which 22 eligible studies published between 2001 and April 2025 were included after rigorous screening. Data were extracted using a standardized framework and synthesized qualitatively due to heterogeneity in study designs, diagnostic methods, and outcome measures. Results: The majority of studies (96%) focused on goats and sheep, highlighting their primary role in disease epidemiology. Reported prevalence varied widely (2.18%-42.26%), with higher susceptibility consistently observed in goats. Seroprevalence studies indicated substantial viral circulation across regions, with notable geographic disparities in research coverage. Diagnostic methods included clinical assessment, competitive enzyme-linked immunosorbent assay, and reverse transcription polymerase chain reaction, with limited integration of advanced molecular tools. Molecular characterization confirmed the exclusive circulation of Lineage IV strains, closely related to those from neighboring countries, indicating transboundary transmission. Key risk factors included age, seasonality, breed, animal movement, and vaccination status. Co-infections with bacterial, viral, and parasitic pathogens were frequently reported, complicating diagnosis and disease management. The locally produced vaccine demonstrated strong immunogenicity, with seroconversion rates exceeding 91% and fieldlevel protection lasting up to 12 months; however, vaccination coverage remains uneven across regions. Conclusion: Despite progress in surveillance and vaccination, significant gaps persist in multi-species epidemiology, advanced diagnostics, co-infection management, and Differentiation of infected from vaccinated animals (DIVA)-compatible vaccine development. Strengthening integrated surveillance, improving vaccination coverage, and adopting rapid molecular diagnostics are critical to achieving PPR eradication targets in Bangladesh by 2030.