Arising Concerns of Atypical Manifestations in Patients with Hand, Foot, and Mouth Disease

Genetic characteristics and phylogenetic analysis of coxsackievirus A6 isolated in Linyi, China, 2022-2023

Hand, foot and mouth disease (HFMD) was one of the most common infectious disease in the past few decades. After 2013, coxsackievirus A6 (CVA6) has replaced enterovirus 71 (EV-A71) and coxsackievirus A16 (CVA16), becoming the predominant pathogen responsible for HFMD in many areas in China. The objective of this study is to investigate the genetic characteristics and molecular epidemiology of CVA6 in Linyi from 2022 to 2023. A total of 965 HFMD cases were enrolled in this study and analyses based on VP1 nucleotide sequences were performed to determine the evolutionary trajectory of CVA6. In 2022, 281 (281/386, 72.8%) were positive for enterovirus (EVs), and 217 (217/281, 77.2%) were CVA6 positive. In 2023, 398 (398/579, 68.7%) samples were positive for EVs, and 243 (243/398, 61.1%) were CVA6 positive. Six sequences were selected from each year for the homology analysis. The results showed that 12 strains isolated in Linyi were far from the prototype strain (AY421764) and the first CVA6 strain reported in China (JQ364886). Phylogenetic analysis showed that the CVA6 strains isolated in Linyi all belonged to D3 subgenotype. CVA6 is emerging as a common pathogen causing HFMD in Linyi, and continuous surveillance of HFMD etiological agents is necessary.

Emerging concerns of atypical hand foot and mouth disease caused by recombinant Coxsackievirus A6 variants in Henan, China

An increasing number of studies have reported that atypical hand, foot, and mouth disease (HFMD) is becoming a new concern for children's health. At present, there is no official definition for atypical HFMD, but some studies have defined that it occurs at anatomic sites not listed in the definition of HFMD issued by the World Health Organization. Several pathogens have been reported to cause atypical HFMD, such as Coxsackievirus (CV)A6. As one of the most prevalent enteroviruses in the world, CVA6 seems to affect a wider range of children and causes more severe and prolonged illness than other enteroviruses. The early lesions of atypical HFMD are very similar to the clinical presentations of other diseases, such as eczema, which poses a challenge for clinicians aiming to identify and diagnose HFMD in a timely manner. Here, we report on six atypical HFMD patients caused by recombinant CVA6 variants, and the atypical manifestations include eczema coxsackium, large herpes, rice-like red papules and herpes, purpuric rash, and onychomadesis, as well as and large red herpes on scalp, perianal, testicles, shoulders and neck, and other atypical eruption sites, hoping to draw the attention of other pediatricians. This study will provide scientific guidance for timely diagnosis of HFMD to prevent serious complications.