Molecular Epidemiological Study of Hand, Foot, and Mouth Disease in a Kindergarten-Based Setting in Bangkok, Thailand.

Nipa Thammasonthijarern,Wirichada Pan-Ngum,Pannamas Maneekan,Pichamon Sittikul,Warisa Nuprasert,Supawat Chatchen,Somboon Hataiyusuk,Pimolpachr Sriburin,Nathamon Kosoltanapiwat,Weerawan Hattasingh,Janjira Thaipadungpanit

doi:10.3390/pathogens10050576

Abstract

Hand, foot, and mouth disease (HFMD) is a contagious childhood illness and annually affects millions of children aged less than 5 years across the Asia–Pacific region. HFMD transmission mainly occurs through direct contact (person-to-person) and indirect contact with contaminated surfaces and objects. Therefore, public health measures to reduce the spread of HFMD in kindergartens and daycare centers are essential. Based on the guidelines by the Department of Disease Control, a school closure policy for HFMD outbreaks wherein every school in Thailand must close when several HFMD classrooms (more than two cases in each classroom) are encountered within a week, was implemented, although without strong supporting evidence. We therefore conducted a prospective cohort study of children attending five kindergartens during 2019 and 2020. We used molecular genetic techniques to investigate the characteristics of the spreading patterns of HFMD in a school-based setting in Bangkok, Thailand. These analyses identified 22 index cases of HFMD (symptomatic infections) and 25 cases of enterovirus-positive asymptomatic contacts (24 students and one teacher). Enterovirus (EV) A71 was the most common enterovirus detected, and most of the infected persons (8/12) developed symptoms. Other enteroviruses included coxsackieviruses (CVs) A4, CV-A6, CV-A9, and CV-A10 as well as echovirus. The pattern of the spread of HFMD showed that 45% of the subsequent enteroviruses detected in each outbreak possessed the same serotype as the first index case. Moreover, we found a phylogenetic relationship among enteroviruses detected among contact and index cases in the same kindergarten. These findings confirm the benefit of molecular genetic assays to acquire accurate data to support school closure policies designed to control HFMD infections.

Highlights

Hand, foot, and mouth diseases (HFMDs) are caused by a group of human enteroviruses of the family Picornaviridae, a highly diverse group of small, non-enveloped, icosahedral viruses with single positive-strand RNA genomes [1,2]
The objectives of this study were to investigate the epidemiology of HFMD and to identify molecular genetic characteristics related to spreading patterns in a real-world setting, in kindergartens and daycare centers in metropolitan Bangkok, Thailand
We show the close phylogenetic relationships among enteroviruses through our analyses of contact and index cases in the same kindergarten. These findings suggest that subsequent enteroviruses with the same serotype as the first index case were closely related to the enterovirus that spread through the kindergarten

Summary

Introduction

Foot, and mouth diseases (HFMDs) are caused by a group of human enteroviruses of the family Picornaviridae, a highly diverse group of small, non-enveloped, icosahedral viruses with single positive-strand RNA genomes [1,2]. More than 20 serotypes of enteroviruses cause HFMD, and the most common causative pathogens include enterovirus A71 (EV-A71) and coxsackieviruses A16 (CV-A16) and CV-A6. HFMD symptoms include fever; vesicular rash on the palms, soles, tongue, or buttocks; sore throat; and ulcers of the lips. Herpangina (HA) is a clinical manifestation of HFMD caused by the same group of enteroviruses, characterized by oral blisters on the roof of the mouth and at the back of the throat without a vesicular rash [7]. HFMD outbreaks have killed many children residing in Southeast Asian countries and in China; for instance, regarding the HFMD cases in Mainland China, the morbidity of the survivors increased from

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