What is hand, foot and mouth disease? Hand, foot and mouth disease is a viral infectious disease that mainly affects infants and preschool children. It can also occur in adults. The pathogens of hand, foot and mouth disease are mainly enteroviruses, and the routes of transmission are mostly pathogens excreted in mucosal secretions such as the oral cavity, nasal cavity, conjunctiva, and the feces of patients. Hand, foot and mouth disease is a common disease in infants and young children. It is highly contagious and serious.