What is foot and mouth disease? Hand, foot and mouth disease is an infectious disease caused by enteroviruses. It is common in children in kindergartens and primary schools, and can also occur in adults. The causative agent of this disease can be spread to others through contact with the patient\’s saliva, urine, feces, and blister fluid. Hand, foot and mouth disease mainly causes lesions in the oral cavity and skin and mucous membranes, usually manifesting as small blisters in the mouth and on the hands and feet. Symptoms of Hand, Foot and Mouth Disease Symptoms of hand, foot and mouth disease can vary depending on the age and condition of the patient. Infants and young children are usually more severely ill, with a sudden rise in body temperature and possible symptoms such as lethargy, anorexia, vomiting and diarrhea.