by Dr. Warren Bohnhoff, DVM

FMD. These three letters could stand for various definitions, but for the last six months those associated with agriculture would immediately think of foot-and-mouth disease. It has galvanized state and federal authorities, produced biosecurity plans on farms that never had them, and induced a phobia of foreign travel among all sections of the population. It has raised food safety fears among the public, and its confusion with "mad cow disease" in the public eye has underscored the difficulty of bringing discussion of sometimes complex animal disease and human health issues into the public domain. It has prompted the re-examination of contingency plans for the control of FMD, brought new agencies such as federal and state emergency management into the preparedness mix, and put disease repulsion activities at this country's borders under intense scrutiny.

FMD is thought to be the most economically devastating animal disease world wide. If FMD were to enter the USA, the cost could reach into billions of dollars. The USA has been free of FMD since 1929 and Canada and Mexico have been free since 1954. Why did the recent British outbreak cause such reaction in the USA when other outbreaks of FMD such as that which devastated the Taiwan hog industry in 1997 did not? Yes, FMD has had an almost worldwide distribution for many years, and we have to ask if the risk to agriculture in the USA is substantially different this year compared to previous years.

The virus affects cloven-hoofed animals, namely cattle, swine, sheep, goats and deer. While it is extremely rare for humans to be affected, they can transmit the virus. The virus can survive for 28 hours in human nasal passages, for 10-12 weeks on clothing or in feed, and for over one year on infected premises. Infected animals as well as carrier animals can spread the virus. It can also be transmitted by vehicles, water, semen, garbage, equipment, facilities, clothing, footwear and feedstuffs. The virus has been reported to have the ability to travel 12 miles over land and approximately 150 miles over the sea. The FMD virus is susceptible to changes in pH and can be destroyed in the presence of heat or low humidity or by certain disinfectants (1-2% formalin, 4% sodium carbonate or sodium hydroxide). Virkon-S has been federally approved as a FMD disinfectant as well.

The mortality (death) rate is not the cause of alarm, being only about 2% on average, but rather the ability of the virus to spread rapidly, near 100% morbidity (infection) rate, and the resulting loss of animal productivity. Recovery time is typically two to three weeks, however, affected animals never achieve previous performance levels (milk and meat production). Hence, without depopulation and isolation for a given time period, economic losses are incurred continuously. The costs of depopulation and loss of milk and meat production for a country infected with FMD can be staggering.

The technical issues associated with FMD control are complex. It is not a disease that behaves in the same way in every outbreak. The seven virus types and numerous sub-types, the wide host range, the very infectious nature of the virus, the short incubation period, and the transmission once the disease has arrived, make planning for FMD outbreaks complex. The one element not available to the planners in the event of an outbreak is time.

Contingency plans for FMD outbreaks have to be in place before an outbreak occurs. There is no time to hesitate or plan on the fly. The first few days of an outbreak are always critical and affect the subsequent course of the disease. As the recent British outbreak has shown, failure to recognize the disease on its first appearance may lead to a proliferation of disease outbreaks at such a pace that they would tax the resources that can be assembled to deal with them. Also, this happens in the earliest stages of a FMD outbreak when the resources are least available. Technological advances in diagnostics, particularly rapid field tests and perhaps vaccine technology, may provide new methods for the control of outbreaks in countries that can afford them. For now, early and precise recognition of clinical cases using traditional veterinary skills and centralized laboratory technologies is essential for control.

Following the most common incubation period of one to seven days (possibly up to 28 days), acute FMD is exhibited by the appearance of blisters in the mouth, on the teats and/or on the feet. These blisters rupture, leaving erosions. Profuse production of sticky, foamy, stringy saliva can be observed along with lameness and a corresponding reluctance to move. Feed intake drops due to the painfully sore mouth. Fever is also common during the first few days. Pregnant animals often abort and production drops (milk and weight gain). Nearly all animals recover and then become carriers of the virus, but production doesn't return to pre-disease levels.

Other diseases have signs similar to FMD, so whenever foot or mouth blisters or other signs typical of FMD are observed and reported, a lab test needs to be done to determine the cause of the symptoms.

The U.S. Department of Agriculture's (USDA) Animal and Plant Health Inspection Service (APHIS) has a strong system in place for detecting and responding to outbreaks of foreign animal diseases, including foot-and-mouth disease in the USA. APHIS' long standing FMD response plan includes eradicating the disease by depopulating affected and exposed animals. They will establish and maintain FMD quarantines and will work with state and local officials to humanely euthanize and dispose of carcasses in approved manners. Also, indemnity would be paid to affected producers for the fair market value of their animals.

As a further precaution against a widespread FMD outbreak, agency officials would also order and have on hand an adequate supply of FMD vaccine from the North American Foot-and-Mouth Disease Vaccine Bank. While APHIS doesn't believe widespread vaccination is an appropriate first step against the disease, vaccinating animals may enhance other eradication activities and help to prevent a more severe outbreak of the disease.