Foot-and-mouth disease

G R THOMSON AND A D S BASTOS

GENERAL INTRODUCTION: PICORNAVIRIDAE

Introduction

Foot-and-mouth disease (FMD) is a highly contagious and usually acute affliction of cloven-hoofed animals and camelids caused by a virus of the family Picornaviridae. The susceptibility of different species to infection and their ability to transmit it, however, are highly variable. In cloven- hoofed livestock the disease is usually characterized by high morbidity, low mortality and the development of vesicles and erosions in the mucosa of the mouth and skin of the interdigital spaces and coronary bands.

During the second half of the nineteenth and first half of the twentieth centuries in western Europe and North America repeated epidemics of rapidly spreading FMD resulted in serious losses, predominantly among high-producing livestock raised under increasingly intensive systems. As the economic effects of the disease and the difficulties of controlling it became apparent, concerted efforts towards eradicating it were undertaken. This was eventually achieved in North America in 1929 and in the European Union in 1992. Among other major livestock producers, Australia only experienced FMD prior to the turn of the nineteenth century and New Zealand has never been required to respond to an outbreak. Japan achieved eradication in 1908.

The logistically difficult and costly efforts required to eradicate the disease resulted in countries which had achieved eradication becoming wary of re-importing it, particularly from regions where exotic types of FMD virus (FMDV) were prevalent. They consequently instituted measures to prevent this, including embargoes on agricultural imports from countries where efficient control is not practised or where the epidemiological situation with respect to FMD has not been accurately established. Embargoes were also sometimes used as barriers to exclude imports of livestock and livestock products from regions that were able to produce them more cheaply than the importer. Curbing the use of non-tariff barriers was one of the objectives of the General Agreement on Tariffs and Trade (GATT) and remains an ideal of its successor, the World Trade Organization (WTO).

In addition, the Office International des Epizooties (OIE), the international animal health body primarily concerned with facilitating international trade in animals and animal products, is increasingly involved in instituting rational guidelines to foster international trade on the one hand without endangering the FMD-free status of major importers on the other. This is proving increasingly contentious because of the conflicting desires of exporters for decreasing restrictions as opposed to the increasing fear of importers for the inadvertent arrival of FMDV in legally as well as illegally imported animals or animal products.

The recent epidemics of FMD that have occurred in countries long free from FMD such as Taiwan, Japan, South Korea, the UK, Ireland, France and the Netherlands,¹³³ have re-emphasized the devastating repercussions that FMD can have. These effects have primarily been economic: the direct and indirect costs of the 2001 outbreak in the UK, for example, may have been as high as US$ 12 billion.^{317, 321} Similarly, the outbreak in Taiwan had far-reaching consequences particularly in the loss of the valuable export market to Japan for pork. However, other issues relating to animal welfare, ecological effects occasioned by large-scale carcass disposal and sociological problems experienced by farming and other rural industries (e.g. tourism) have also been profound.^{78, 205, 315} This upsurge in the prevalence of FMD has emphasized the difficulties of protecting countries and regions of the world free of FMD from reincursion of the infection. It also highlighted the extraordinary measures necessary to protect the livelihoods of farmers whose livestock and products are subject to movement restriction/ market access as a result of FMD outbreaks.⁶⁵

Perhaps the most profound effect of these events on the conventional approach to animal health has been the questioning of accepted control practices on both technical and moral grounds. It is clear that in both developed and developing countries large-scale ‘stamping out’ (slaughter of infected and in-contact animals, and burial or incineration of the carcasses) is no longer socially or politically acceptable. This presents a new and acute challenge in the field of animal health control.

It is an unfortunate fact that FMD is still widespread in Africa, although in North and southern Africa considerable success in reducing the prevalence of the disease and in developing FMD-free zones has been achieved. In many countries outside these two regions there is little attempt to control the infection while in others the policies and practices applied sometimes ignore important epidemiological principles and are therefore largely futile. If this situation is not changed it will continue to retard the development of many parts of Africa, particularly in the arid zones of the continent. The reason is simply that livestock are one of the few tradable commodities that those in arid parts of Africa possess and FMD, together with some other important infections of livestock, precludes access of livestock and livestock products from countries in these regions to international markets where good prices are achievable. If, on the other...