The virus is secreted in an infected animal's saliva, feces, urine, milk and semen. Excretion of the virus begins a few days before signs of the disease develop. Pigs, in particular, excrete large numbers of virus particles. Airborne spread of the disease occurs easily. FMD can also be spread physically from farm to farm so that movement by animals, people or materials can transmit the disease.
Infected animals can spread the virus to other susceptible animals.
People wearing contaminated clothes or footwear, or using contaminated equipment can spread the disease to animals. For instance, someone walking over rural land can pick up the virus on their boots and then deposit viral particles where they walk to be picked up by grazing animals. Facilities and vehicles used to hold and move susceptible animals may be contaminated. Susceptible animals exposed to contaminated materials such as hay, feed, water, semen, biologics or raw or improperly cooked food waste are at a high risk of infection. The disease is rarely fatal, except in very young animals.