Molecular epidemiology and evolutionary studies of human rhinovirus and enterovirus 68 in Thailand

Abstract

Acute respiratory tract illness is respiratory diseases that affect the air passages frequently occurs in rainy and winter seasons causing many diseases such as common cold, pneumonia, bronchitis, and asthma exacerbation. Many kinds of virus have been well recognized associated with the respiratory diseases. Publications worldwide have reported on the emerging of human rhinovirus (HRV) species C in 2007 and the re-occurrence of human enterovirus 68 (HEV68), a rarely detected pathogen usually causes respiratory illness. At present, epidemiological data, clinical complication and evolutionary history regarding these viruses in particular on the Asia continent are still limited. To address these concerns, this study aimed to establish comprehensive population-based surveillances during 2006-2012 (n = 2083), and provided evidence for their impacts in childhood respiratory tract illnesses. Employing PCR approaches for common respiratory virus detection, our study revealed that 45% of enrollment children were infected with at least one viral agent, and HRV being one of the most common viruses detected with annual prevalence of 13.8%. Results displayed that infections by HRV in both of influenza-like illnesses and lower respiratory tract illness patients predominantly targeted very young children with viral pneumonia, bronchiolitis and wheezing were the common discharged summary. The majority of HRV species identified in Thailand was HRV-C (48%). In contrast to HRV, HEV68 prevalence was estimated at 1.4% with main target group in older children. No significant respiratory complication was found between number of case of HRV, HEV68 and other respiratory viruses. The activity of respiratory viruses identified in Thailand showed significantly direct correlation with the relative humidity. Taken all evidence together, this study suggested that respiratory viruses circulating in Thailand were widely diverse, and the epidemics profile displays species, season, and year variations as the consequence of less distinct among seasonal oscillation . Furthermore, results obtained from Bayesian MCMC analysis suggested that HRV-C was not a recently emerged human pathogen. Otherwise, it was probable the descendent of the closely related HRV-A for >750 yrs, and at least presented in human community for 10 yrs. Analysis of evolutionary force sharped HRV and HEV68 diversification indicated, as similar to other picornavirus, the evolutionary status of these viruses were relatively stable and undergo with strong purifying selection.