Epidemiology of hand foot and mouth disease caused by Cox A6 in Guangdong, 2017–2019

  Objective  To understand the epidemiological characteristics of hand foot and mouth disease (HFMD) caused by coxsackievirus A6 (Cox A6) in Guangdong province from 2017 to 2019.

  Methods  A total of 22 sentinel hospitals in 21 cities and Shunde district of Foshan were selected to conduct surveillance for common type of HFMD caused by Cox A6. The incidence of HFMD caused by Cox A6 was estimated and the population and time distribution characteristics of the disease were analyzed based on the case number and outbreak data.

  Results  The annual proportions of HFMD caused by Cox A6 in Guangdong were 57.1%, 23.0% and 47.4% during 2017–2019. The proportion of HFMD outbreak due to Cox A6 was 18.5% (12/65), ranking only second to that by Cox A16, and HFMD caused by Cox A6 mainly occurred in September and June. The estimated incidence showed a decreasing trend with age (χ²=2683320.620, P<0.001). The incidence was highest in age group 1 year (4092.17/100 000), followed by that age group 2 years (2057.02/100 000), 0 year (1650.29/100 000) and 3 years (1530.23/100 000). There was an increasing trend with month age (χ²=771.582, P<0.001). The incidence was highest in age group 11 months (4982.7/100 000), followed by that in age group 10 months (4150.7/100 000) , 9 months (3523.2/100 000), 8 months (2684.97/100 000) and 7 months (1813.01/100 000). The incidence was highest in September (34.99/100 000), followed by that in July (30.98/100 000), October (28.88/100 000), August (24.18/100 000) and June (22.04/100 000). The proportion of severe and death cases due to Cox A6 was 25.2% (86/341), ranking only second to that by EV71 (35.5%, 121/341).

  Conclusion  Cox A6 infection has become one of the main types of HFMD in Guangdong, and the epidemic intensity of Cox A6 infection varied from year to year. The outbreak intensity ranked only second to that of Cox A16 infection. When the Cox A6 infection level was high, the number of outbreaks increased, which mainly occurred in child care settings, and Cox A6 infection was common in September and June. Children aged 0–3 years and 6–11 months are at high risk. The intensity of severe disease and death was lower than that of EV71 but higher than that of Cox A16. The proportion of severe and death cases was higher than those reported by previous studies.