Coxsackievirus A6 and Hand, Foot and Mouth Disease: Three Case Reports of Familial Child-to-Immunocompetent Adult Transmission and a Literature Review.

Hand, foot and mouth disease (HFMD) is a highly contagious viral infection characterized by typical maculopapular or vesicular eruptions on the hands and feet and in the oral cavity. It affects predominantly children and/or immunocompromised adults. It usually follows a benign and self-limiting course. However, HFMD cases with severe or lethal complications such as encephalitis, meningitis, pulmonary edema and myocarditis have also been reported, mostly in children, but also in adults. High infectivity of HFMD has contributed to several large outbreaks of this disease in recent decades in East and Southeast Asia, the United States and Finland. The most common pathogens were Coxsackievirus A16, Enterovirus 71 and, recently, also Coxsackieviruses A6 and A10. Differences in the course of HFMD have been observed, depending on the virus type. Recently, many cases of atypical HFMD have been described in the literature with unusual morphology and/or localization of skin lesions. Atypical HFMD manifestations including vesiculobullous exanthema, often on the trunk or extremities, and perioral zone involvement were often caused by Coxsackievirus A6 infections. We present 3 cases of familial transmission of HFMD caused by Coxsackievirus A6 with some atypical features, benign course and complete recovery among immunocompetent adults.