Co-circulation of multiple serotypes of foot and mouth disease virus among susceptible multispecies animal population in India during 2021-2022

Abstract

India, with over 535 million livestock, is one of the largest and most densely populated countries in Asia in terms of livestock population. Transboundary animal diseases, such as foot and mouth disease (FMD), pose significant constraints on the development of progressive livestock enterprises in developing countries. During 2021–2022, a relatively higher number of suspected FMD outbreaks were reported across multiple species in most states and union territories (UTs). In addition to cattle, other affected species included buffalo, sheep, goat, pig, mithun, and yak. Clinical samples (tongue epithelium, oral mucosa, oral swab, foot or snout epithelium, and saliva) were collected from these species and tested using in-house serotyping ELISA, followed by reverse-transcription multiplex PCR. Multiple FMDV serotypes were detected in different states and UTs. For example, both serotypes O and A were detected in six states: Maharashtra, Uttar Pradesh, Punjab, Odisha, Nagaland, and Karnataka. Serotype O alone was identified in 23 other states/UTs. All three serotypes including O, A, and Asia 1 were detected in Tamil Nadu and Jammu & Kashmir. The detection of multiple FMDV serotypes across different states and animal species indicates the co-circulation of diverse virus strains, which presents a significant challenge for disease control and prevention. Factors contributing to the spread and persistence of the disease include the common practice of mixed farming in India, where multiple species are housed together, and the migratory nature of small ruminant flocks, particularly in regions like Jammu and Kashmir. Additionally, the cyclic pattern of FMD incidence, likely influenced by delayed vaccination and waning immunity from natural infections, further complicates the epidemiological landscape. Given the complexity of the situation and the diversity of circulating FMDV serotypes, implementing a monovalent vaccine program is currently not advisable. Instead, a comprehensive FMD control strategy is essential. This should be informed by detailed epidemiological analysis and surveillance and supported by the use of high-quality vaccines, accompanied by uniformly practiced and timely vaccination efforts, to effectively manage the disease and mitigate its impact.