Foot-and-mouth disease is a severe viral disease that can spread quickly among cloven-hoofed animals including cattle, sheep, pigs, goats and cervids. While it is not a public health risk to humans and has not been found in the U.S. since eradication in 1929, a detection in the U.S. could devastate livestock industries. It’s important to be prepared for action, should an outbreak occur, and maintain diligence in preventative measures through daily and enhanced biosecurity planning. 

This three-part series is provided to help livestock producers be prepared for an outbreak before it occurs:

1.  What is foot-and-mouth disease, 
2.  The potential economic and operational impacts and FMD on public lands grazing, and 
3.  Preparation for foot-and-mouth disease and maintaining continuity of business

What is Foot-and-Mouth Disease? 

There has been increasing discussion about foot-and-mouth disease in industry trade journals and at Cattlemen’s and Woolgrowers meetings. So why the fuss about a disease that has been eradicated from the U.S. for almost 100 years? Because, it is now found in more than two-thirds of the world, and U.S. veterinarians and state and federal livestock officials predict that it is not a matter of if it will once again reach the U.S., but a matter of when it will reach the U.S. 

Foot-and-mouth disease in livestock is not the same as, or related to, “hand-foot-and-mouth disease (a viral human disease common in children. Foot-and-mouth disease is designated by United States Department of Agriculture, Animal Plant Health and Inspection Service (USDA, APHIS) as a Tier 1 (highest risk and consequence disease of national concern) foreign animal disease. It is considered the most contagious viral disease that causes illness in cattle, pigs, sheep, goats, deer and other animals with divided hooves. It does not affect horses, dogs or cats. 

Though not a public health risk, an outbreak of foot-and-mouth disease in the U.S. would still have serious economic and operational impacts. Foot-and-mouth disease is not transferable to humans (not zoonotic), and meat, milk and fibers would remain safe for human consumption and use. However, an outbreak would likely cause severe supply chain interruptions and livestock export restrictions, reducing the available amount of marketable meat and milk. This could significantly increase prices paid by consumers and impact food security, especially in lower-income households. 

Planning for an outbreak

Assuming that you as a producer are engaged in your industry livestock quality assurance program, you have already taken positive steps to protect and maintain the health of your animals and enterprise. Developing and implementing a basic or daily biosecurity plan for your operation is the next level of protection. This will greatly reduce risks and provide the foundation for an enhanced biosecurity plan approved by the state animal health official, which will be required in order to obtain a movement permit for noninfected animals during an outbreak of foot-and-mouth disease or another foreign animal disease. University of Nevada, Reno Extension has created a Livestock Biosecurity website (https://extension.unr.edu/livestock-biosecurity/resources.aspx) to provide producers national and Nevada-specific biosecurity information to assist in development of both daily and enhanced biosecurity plans.

A tremendous amount of ongoing work and planning on behalf of industry, government and academia has established plans for continuity of business (minimizing operational and economic loss) in preparation for the possibility of a domestic outbreak. National cattle, sheep, pork and dairy associations and USDA-APHIS have provided funding and collaborated with the Center for Food Security and Public Health, Iowa State University College of Veterinary Medicine to develop secure food supply plans for beef, sheep, goat, pork and milk. The Secure Beef Supply Plan, and Secure Sheep and Wool Supply plan are hyperlinked in this article. These websites contain detailed information about what the disease is, how to identify it, how animal and animal byproduct movement will be controlled, and how to minimize exposure to it and maintain continuity of business through enhanced biosecurity plans. The websites are structured to provide producers with the ability to develop their own unique enhanced biosecurity plan or information on who to contact to get local assistance. In Nevada, University of Nevada, Reno Extension Livestock Specialist Tracy Shane and Extension Agricultural Educator Gary McCuin have completed training courses on both of the plans mentioned above and are available to assist in plan development or provide workshops to interested parties.

Grazing on public lands is highly variable in scope and context, and managing livestock grazing on public lands during an outbreak poses unique challenges for ranchers and government officials. An effective response will require interagency collaboration with the federal land management agencies and the state and federal officials managing the outbreak. An advisory group of public land grazing stakeholders consisting of Western states sheep and cattle producers, the Public Lands Council, state animal health officials, Bureau of Land Management, U.S. Forest Service, U.S. Fish & Wildlife Service, USDA Wildlife Services, USDA Animal and Plant Health Inspection Service, the American Sheep Industry Association, and the National Cattlemen’s Beef Association worked together to determine livestock management options and movement decision guidance criteria.

Symptoms, spread and effects on livestock

“The main constraints in controlling this disease and why it is considered as the most dreaded viral disease are its high contagiousness, wide geographical distribution, broad host range, ability to establish carrier status, antigenic diversity leading to poor cross-immunity, and relatively short duration of immunity. Poor surveillance and diagnostic facilities as well as inadequate control programs are major problems in control of this disease.” (Neeta Longjam, 2011).

There are seven different types and numerous (60+) variants of the disease. This is significant because each of the numerous types and variants are independently infectious. That means that if an animal is infected with, or vaccinated against, one strain or subvariant, it can still become infected by any of the other variants or subvariants.

Although there are currently effective vaccines for the disease, they are type- and strain-specific and do not result in universal resistance. More than 50% of ruminants that recover from the disease or are vaccinated and subsequently exposed to the virus can become carriers of the disease. The carrier state can last for up to 3.5 years in cattle, nine months in sheep and more than five years in African buffalo (Merk Veterinary Manual, 2021). The incubation period of the disease is variable and depends on the host, environment, route of exposure and virus strain. After infection with the virus, the average incubation period is three to eight days for sheep and goats, less than two days for pigs and two to 14 days for cattle (Merk Veterinary Manual, 2021).

Even though foot-and-mouth disease is the most contagious viral disease of cloven-hoofed animals, it is not usually fatal, at least to adult animals. Infected adult animals often show no or mild clinical signs that may not become apparent for two to four days after infection. Visual symptoms may include fever and blisters (vesicles) on the tongue and lips, in and around the mouth, and on teats and feet. When blisters erupt, they turn into reddened erosions that are painful and can lead to other conditions, such as depression, lack of appetite, excessive salivation, mastitis, lameness and a reluctance to move or stand. The disease may be fatal to calves and lambs through heart disease (myocardia) that can result in a high mortality rate of up to 90%. It is important to be aware that animals can transmit the virus before the appearance of clinical signs (Merk Veterinary Manual, 2021).

The virus is shed in saliva, breath, milk, semen, urine, wool, meat and manure. It can be spread directly between animals or indirectly on clothing, footwear, vehicles and equipment. The virus is environmentally resistant and can remain viable for months. Compounding these issues, symptoms can be mistaken for a number of other diseases in sheep and cattle. These include vesicular stomatitis, Bovine Viral Diarrhea (BVD), malignant catarrhal fever, foot rot in cattle and Scrapie’s in sheep. The disease affects a wide range of cloven-hoofed animals, including domestic animals and more than 70 wildlife species, including brown and black bears. With the potential of disease to spread between livestock and wildlife, it is a concern of state and federal wildlife agencies.

Treatment, control and prevention of foot-and-mouth disease in animals

1. In regions that are generally free of the disease, control of the disease is typically attempted by culling all animals on infected premises, and animal movement controls are imposed to reduce the risk of virus spread.
2. Vaccination around outbreaks may be used to limit the spread of the disease in both affected and nonaffected areas.
3. No treatments for infected animals are available.

Rapid disease reporting is essential to control an outbreak in nonendemic countries.  

The next article in this series will cover the potential impact of foot-and-mouth disease and the management of the disease on public grazing lands.