Early Symptoms of Hand, Foot and Mouth Disease and Timely Detection Methods Early Symptoms of Hand, Foot and Mouth Disease Hand, foot and mouth disease is an infectious disease caused by enterovirus. It usually occurs in infants and kindergarten children. Its incubation period is generally 3-7 days. The early symptoms of hand, foot and mouth disease mainly include the following aspects. 1. Fever Hand, foot and mouth disease is often accompanied by fever in the early stages. For example, infants and young children may have symptoms such as high fever, thirst, restless sleep, and loss of appetite. Children may