Subdistrict-Level Reproductive Number for Foot and Mouth Disease in Cattle in Northern Thailand.

Orapun Arjkumpa,Veerasak Punyapornwithaya,Andres Perez,Catalina Picasso-Risso

doi:10.3389/fvets.2021.757132

Orapun Arjkumpa, Veerasak Punyapornwithaya + Show 2 more

Open Access

https://doi.org/10.3389/fvets.2021.757132

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Abstract

Foot and mouth disease (FMD) is an important contagious transboundary disease that causes a significant economic loss for several countries. The FMD virus (FMDV) can spread very rapidly by direct and indirect transmission among susceptible animals. The complexity and magnitude of FMDV transmission at the initial stages of the epidemic can be expressed by the basic reproductive number (R0), and furthermore, control strategies can be assessed by the estimation of the effective reproductive number. In this study, we aimed to describe FMD outbreaks among smallholder cattle farms by subdistricts in the northern Thailand and compute the effective reproductive number for outbreaks caused by FMDV serotype O and overall serotypes, including serotype O, serotype A, and unidentified serotype, at the subdistrict level (Rsd) using an epidemic doubling time method. Field data of FMD outbreaks during 2015–2017 that affected 94 subdistricts in northern Thailand were assessed to estimate the Rsd. Results showed that 63.38% (90/142) of the FMD outbreak episodes in cattle were caused by FMDV serotype O. The average doubling time and the Rsd estimated of the outbreaks caused by FMDV serotype O and overall serotype were 2.80 and 4.67 months, and 1.06 and 1.04, respectively. Our results indicated that transmission of FMD in cattle at the subdistrict level in northern Thailand was not controlled (Rsd > 1), which indicates the endemicity of the disease in the region. Although control measures are in place, the results from this study highlighted the need for enhancing FMD monitoring and control strategies in northern Thailand.

Highlights

Foot and mouth disease (FMD) is the foremost viral transboundary and highly contagious vesicular animal disease affecting cloven-hoofed animals [1, 2]
The disease is caused by the FMD virus (FMDV), a single-stranded positive-sense RNA virus belonging to the genus Aphthovirus of the Picornaviridae family [4, 5]
There were 142 outbreak episodes of FMDV in cattle, and 90 (63.38%) of those were identified as serotype O between 2015 and 2017

Summary

Introduction

Foot and mouth disease (FMD) is the foremost viral transboundary and highly contagious vesicular animal disease affecting cloven-hoofed animals [1, 2]. Seven distinct non-cross-immunity FMDV serotypes are circulating globally, namely, A, O, C, Asia-1, South African territories 1, 2, and 3 [3, 5,6,7]. Different serotypes of FMDV were reported in 77% of the worldwide livestock population located in countries of Africa, the Middle East, and Asia and constrained zones of South America [7]. In Southeast Asia, four FMDV serotypes including A, O, C, and Asia 1 have circulated over recent years [8]. The incidence and serotype specificity of FMDV vary across different Asian countries [8, 9]. During the past decade in Southeast Asia, FMDV serotype O outbreaks have been spreading and becoming endemic in certain areas, including Thailand and neighboring countries [8]

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