Clinical Manifestations of Coxsackievirus A6 Infection Associated with a Major Outbreak of Hand, Foot, and Mouth Disease in Japan

A serious outbreak of hand, foot, and mouth disease (HFMD) occurred in Japan in the summer of 2011 (1,2). A major cause of this epidemic was coxsackievirus A6 (CA6), and the clinical manifestations of the disease differed from those of typical HFMD. The Infectious Diseases Control Law mandates medical doctors in Japan to officially report cases exhibiting the following symptoms immediately after diagnosis: fever with sore throat and appetite loss, followed by the appearance of reddish vesicles on the hands and feet approximately 2 days after the onset of fever. The vesicles usually disappear within 7 to 10 days without specific treatment. Reported cases should satisfy both of the following clinical criteria: (i) vesicles measuring 2-5 mm with blisters on the palm of the hand and sole or dorsum of the foot and oral mucosa and (ii) vesicles that heal without crust formation.