Epidemiological Surveillance and Mutational Pattern Analysis of Foot-and-Mouth Disease Outbreaks in Bangladesh during 2012–2021

Abstract

Foot-and-mouth disease (FMD) in cloven-hoofed animals is considered an economically devastating disease in endemic countries like Bangladesh, where the livestock sector contributes to a greater portion of the nation’s economy. The causative agent of the disease, foot-and-mouth disease virus (FMDV), equipped with higher mutational frequency challenges the efficacy of the existing vaccine and control measures. This study, including 32 districts and 71 outbreaks to reveal epidemiological patterns and mutational trends of FMDV over the past 10 years (2012–2021), reported a 54.7% prevalence of FMD, with the majority of outbreaks occurring during the rainy season. Different risk factors such as age, gender, farming system, and vaccination status demonstrated a significant association with FMD cases which was confirmed by the χ2 test ( $p<0.05$ ). VP1 sequence analyses reported the predominance of serotype O (85%) over serotype A (11%) and serotype Asia 1 (4%). Bangladesh has foreseen the emergence of several novel FMDV strains during this decade. Novel sublineages, Ind-2001BD1 (Ind-2001e) and Ind-2001BD2, were reported under serotype O, the G-IX lineage of serotype Asia 1 emerged in 2018, and most recently in 2021, a new genotype named MYMBD21 under the lineage SA-2018 was detected for the first time in Bangladesh. Until now, Ind-2001e (Ind-2001BD1) sublineage under serotype O became the predominant sublineage in Bangladesh. From the mutational trend analysis, highly variable sites were observed at positions 138 and 140 within the G-H loop for serotype O. For serotype A and Asia 1, 45th and 44th residues within the B-C loop showed the highest amino acid variations, respectively. A changing mutational pattern among the 2019–2021 FMDV O and A isolates was also observed. The findings of the study would be crucial to understand the FMD situation and designing necessary preventive steps according to the progressive control pathway for FMD control in Bangladesh.