Clinical features and phylogenetic analysis of severe hand-foot-and-mouth disease caused by Coxsackievirus A6

Background: Coxsackievirus A6 (CA6) infection may lead to high hand-foot-and-mouth disease (HFMD) aggregation in children. We aimed to analyze the clinical and phylogenetic features of severe CA6-associated pediatric HFMD. Methods: The clinical and laboratory features of 206 and 55 children with mild and severe CA6-associated HFMD, respectively, were summarized. The CA6 phylogenetic tree was depicted using combinatorial analysis of the VP1-encoding regions and neighbor-joining method. Results: CA6 was the major pathogen both in mild and severe HFMD in 2017. Most CA6-associated severe HFMD cases showed high fever, skin rash, age younger than 36 months, and elevated white blood cell and C-reactive protein levels, and there were no significant differences compared to the mild cases (p > 0.05). The severe cases were significantly more likely (p < 0.05) to show male sex, long fever duration, decreased oral intake, tonsil enlargement, diarrhea, vomiting, elevated levels of creatine kinase and blood glucose, and positive fecal occult-blood test results. Severe complications included aseptic meningitis (29/55, 52.7%) and pulmonary edema (6/55, 10.9%) were observed in severe cases. Furthermore, genetic analyses showed all CA6 isolates belonged to lineage E2, and two amino acid changes of V174I and T283A in VP1 may be associated with the severity of HFMD. Conclusions: CA6 has become a major cause of HFMD with severe systemic disorders. V174I and T283A of VP1 may be associated with the severity of CA6 infection. These findings could raise awareness of the clinical importance of CA6 infection among practitioners.