Mechanism of FMD Outbreaks and its Control in Asian Region

Abstract

Foot-and-mouth disease (FMD) outbreaks by serotype O are dominant in Asia. Topotypes fall mostly into two groups – Southeast Asia (SEA) and Middle East-South Asia (ME-SA). FMD viruses of the SEA topotype (Mya-98 lineage) recently spread widely in Southeast Asia and East Asia. Economic damage by FMD outbreaks in Japan and Korea were very severe in 2010-2011. FMD outbreaks by serotype A are sporadically observed in the region. Serotype Asia 1 newly appeared in Pakistan from 2010 and Bahrain and Iran in 2011. Neighboring countries should take note that there is no matching vaccine available for Asia 1 at this moment. Preparing good matching vaccines is very important for controlling the disease in the Asian region. There are several good matching vaccines for the recent FMD outbreaks by type O (SEA topotype) and type A (Asia topotype). In some cases, however, such as recent outbreaks due to Asia 1 and SEA topotypes, no such matching vaccines are currently available. Officials in countries the region should therefore be aware that a good matching vaccine is not always available and without a good vaccine candidate, early detection and eradication of the disease are critical points in such cases as FMD. In addition, control tools that are different from FMD vaccine are required to prevent pandemic outbreaks and economic catastrophes. Since it takes 7 to 10 days for pigs to produce enough antibodies against FMD virus (FMDV) infection through vaccination, infected pigs continue to excrete a large amount of FMDV in the early stage of infection after emergency vaccination. It is often observed that FMD outbreaks in pigs become large-scale outbreaks and sometimes inflict serious economic damage. It is therefore desired to develop new prompt tools to inhibit FMDV infection or virus excretion from pigs. Antiviral agent exhibit much more prompt and faster effectiveness than vaccine in inhibiting virus excretion from infected animals. In order to inhibit FMDV excretion from infected pigs, which are called amplifiers in FMD, an antiviral agent, T-1105, an pyrazine carboxamide derivative, was developed as a novel tool expected to show prompt efficacy in controlling FMD in pigs.