Foot and mouth disease: Epidemiology

Host/virus Interaction

Contents

General Introduction

Virus

Host

Host/virus Interaction

Environment

In FMD enzootic areas, there is a constant evolution of both the host, to avoid the pathogenic effect of the virus, and the virus, to evade the immune defence mechanisms of the host.

The shorter generation time of the virus allows the virus to change more rapidly than the host, but the restricted repertoire of changes in the genomically more primitive virus reduces its potential to change relative to the host.

In order to survive, the virus must persist in the host or environment sufficiently long to infect a new host.

This predisposes to:

1. The development of reduced pathogenicity and mortality of the host
2. Increased transmissibility
3. Increased period of transmissibility
4. Persistent infection
5. Antigenic variation, if there is active immunity
6. Increased survival time in the environment

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