Spatiotemporal distribution of foot-and-mouth disease in Nepal between 2019 and 2021

Abstract

Foot-and-mouth disease (FMD) is a highly contagious viral disease affecting cloven-hoofed livestock. It is caused by the FMD virus (FMDV), which has seven distinct serotypes (O, A, C, SAT I, SAT II, SAT III, and Asia 1). In Nepal, FMD is a prevalent and economically important livestock disease, with hundreds of outbreaks yearly across different regions. However, there is limited understanding of the recent epidemiological trends of FMD in the past few years in Nepal. This study aims to analyze the spatial and temporal distribution of FMD in Nepal from 2019 to 2021. The FMD and TADs Investigation Laboratory, under the Government of Nepal, conducts annual risk-based surveillance of FMD in the country. The nonstructural protein (NSP) serosurveillance and serotyping (for outbreak confirmation) data from this laboratory were used for the study. The samples were collected either by the laboratory staff or were sent to the laboratory. Data analysis and mapping were performed using Epi info version 7.2.5.0 and QGIS version 3.22.5, respectively. Our findings revealed that 37.65% of samples (n = 417) tested positive for serotyping. The highest number of positive cases occurred in March–April, followed by December. Geographically, the Terai region had the most positive cases, followed by hills and mountains. The positivity rate for serotyping did not significantly vary by animal species (p > 0.05). Serotype O was the dominant serotype in all years, accounting for 98% of cases, while serotype A was found in only 2% of serotype-positive samples. In NSP serosurveillance, out of 3216 samples tested, 15.07% (474/3146; 95% CI, 13.86–16.36) tested positive. NSP seropositivity varied significantly by year (p < 0.001) but not by eco-zone (p > 0.05). In conclusion, FMD remains endemic in Nepal, with a consistent epidemiological pattern except that the Asia 1 serotype was not detected in the past years. We recommend expanding FMD surveillance activities to high-risk areas and collecting data on potential risk factors driving FMD infection in the country. This will enable the implementation of suitable control measures.