Impact of mass vaccination on the spatiotemporal dynamics of FMD outbreaks in India, 2008–2016

Authors: GUNASEKERA, UMANGA - University Of Minnesota; BISWAL, JITENDRA - Indian Council Of Agricultural Research (ICAR); MACHADO, GUSTAVO - University Of Minnesota; RANJAN, RAJEEV - Indian Council Of Agricultural Research (ICAR); SUBRAMANIAM, SARAVANAN - Indian Council Of Agricultural Research (ICAR); ROUT, MANORANJAN - Indian Council Of Agricultural Research (ICAR); MOHAPATRA, JAJATI - Indian Council Of Agricultural Research (ICAR); PATTNAIK, BRAMHADEV - Pipestone Veterinary Services; SINGH, RABINDRA PRASAD - Indian Council Of Agricultural Research (ICAR); Arzt, Jonathan

Submitted to: Transboundary and Emerging Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/18/2022
Publication Date: 9/25/2022
Citation: Gunasekera, U., Biswal, J.K., Machado, G., Ranjan, R., Subramaniam, S., Rout, M., Mohapatra, J.K., Pattnaik, B., Singh, R., Arzt, J. 2022. Spatiotemporal dynamics of foot-and and-mouth disease outbreaks in India, 2008-2016. Transboundary and Emerging Diseases. https://doi.org/10.1111/tbed.14528.
DOI: https://doi.org/10.1111/tbed.14528

Interpretive Summary: Foot-and-mouth disease (FMD) is widespread in India, but does not exist in the USA. For many years the Indian agricultural authorities have vaccinated cattle against FMD. The purpose of this study was to evaluate the mass vaccination of cattle against FMD in India between 2008-2016. The main approach was to examine the amount of vaccine in different states of India and compare to the amount of disease that occurred and the immune status of the cattle in each region. Overall, as more vaccine was delivered, the immune status of the cattle improved and the amount of disease outbreaks decreased. This suggests the vaccine program is effective in India. These findings enhance understanding the usefulness of vaccination against FMD in India, and would be useful in the event of an outbreak of FMD in USA.

Technical Abstract: Foot-and-mouth disease (FMD) is endemic in India, where circulation of serotypes O, A and Asia 1 is frequent. In the past two decades, many of the most widespread and significant FMD lineages globally have emerged from the South Asia region. Here, we provide an epidemiological assessment of the ongoing mass vaccination programs in regard to post-vaccination monitoring and outbreak occurrence. The objective of this study was to quantify the spatiotemporal dynamics of FMD outbreaks and to assess the impact of the mass vaccination program between 2008 to 2016 with available antibody titer data from the vaccination monitoring program, alongside other risk factors that facilitate FMD spread in the country. We first conducted a descriptive analysis of epidemiological outcomes of governmental vaccination programs in India, focusing on antibody titer data from >1 million animals sampled as part of pre- and post-vaccination monitoring and estimates of standardized incidence ratios calculated from reported outbreaks per state/administrative unit. The percent of animals with inferred immunological protection (based on ELISA) was highly variable across states, but there was a general increase in the overall percent of animals with inferred protection through time. In addition, the number of outbreaks in a state was negatively correlated with the percent of animals with inferred protection. Because standardized incidence ratios of outbreaks were heterogeneously distributed over the course of eight years, we analyzed the distribution of reported FMD outbreaks using a Bayesian space-time model to map high-risk areas. This model demonstrated a ~50% reduction in the relative risk of outbreaks in states that were part of the vaccination program. In addition, states that did not have an international border experienced reduced risk of FMD outbreaks. These findings help inform risk-based control strategies for India as the country progresses towards reducing reported clinical disease.