Foot-and-mouth disease: a review of the virus and the symptoms.

Foot-and-mouth disease virus (FMDV) is the etiologic agent of foot-and-mouth disease (FMD), which is a disease of cattle, swine, and other cloven-footed animals. FMD is characterized by the formation of vesicles on the tongue, nose, muzzle, and coronary bands of infected animals. The virus has several unique characteristics that enable it to cause one of the most economically devastating diseases in today's world. The ease with which it may be transmitted by contact and aerosol, combined with its enhanced ability to initiate infections, virtually ensures that most, if not all, animals in a herd will contract FMD. The long-term survival of FMDV in infected animals' tissues and organs, especially when refrigerated, offers an opportunity for its national and international transmission through the food chain. Multiple serotypes and numerous subtypes reduce the effectiveness and reliability of vaccines. The possible development of carriers in vaccinated animals and those that have recovered from FMD provides additional potential sources of new outbreaks. These features create a disease that can have a major economic impact on farmers and entire nations.