Aetiology
The most common viruses implicated are a group of enteroviruses known as the coxsackieviruses. Coxsackievirus A16 (CV-A16) infection is the most common cause, but A4 through A7, A9, and A10 infections also occur.[1][2][3][4][5] Enterovirus 71 (EV71) also causes this disease, but a more severe version.[1][2][3][4][5][7][8][9] EV71 infection is uncommon in the US and Europe. Aetiological changes in the main pathogenic agents of hand-foot-and-mouth disease have been noted in Hunan province in China. The number of patients hospitalised with the disease caused by EV71 and CV-A16 declined between 2014 and 2017, while the number of cases caused by other enteric viruses increased.[14] The enteroviruses are icosahedral non-enveloped viruses that are approximately 30 nanometres in diameter. The genome is made of a single-stranded linear molecule of RNA. Enteroviruses resist lipid solvents and tolerate a wide range of pH and temperature. They are inactivated at temperatures of >50°C (>122°F), but remain infectious at refrigerator temperatures.
Pathophysiology
The infection occurs when a susceptible person is exposed to the virus by means of direct contact with nose and throat discharges, saliva, vesicle fluid, or faecal material from an infected person. The virus may persist in faecal material for up to 1 month. After contact, the virus spreads to regional lymph nodes within 24 hours and viraemia rapidly follows, with spread of the virus to the oral mucosa and skin causing the vesicular rash. The incubation period is 4 to 7 days; however, there may be a prodromal period of 3 to 4 days. Lesions in the mouth heal within 1 week, and lesions on the hands and feet may last for up to 10 days.[1][2][3][4][5][6][7]
Classification
Viral classification
Hand-foot-and-mouth disease is due to infection by some of the enteroviruses. The most common viruses implicated are the coxsackieviruses. Coxsackievirus A16 infection is the most common cause, but A4 through to A7, A9, and A10 infections also occur.[1][2][3][4][5][6]
Enterovirus 71 (EV71) also causes this disease, but a more severe version.[1][2][3][4][5][6][7][8][9][10]
Enteroviruses belong to the Picornaviridae family of viruses; polioviruses, coxsackieviruses (groups A and B), and echoviruses are groups of enteroviruses. More recently identified enteroviruses have not been included in the original classification and have been allocated numbers (i.e., serotypes 68 to 71).
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