Contamination of Human Bocavirus Genotypes 1, 2, 3, and 4 in Environmental Waters in Thailand

Human bocavirus (HBoV) has been recognized as one of the common pathogens which cause respiratory disease and acute gastroenteritis in children worldwide. Recently, our studies reported the detection of HBoV in children with acute gastroenteritis and in oysters in Thailand. However, studies on the presence of HBoV in environmental waters in Thailand have not yet been conducted. In this study, 126 environmental water samples collected from November 2016 to July 2018 were investigated. Detection of HBoV was based on amplification of the VP1/VP2 region of the HBoV genome by nested PCR followed by nucleotide sequencing and phylogenetic analysis. HBoV was detected in 34 out of 126 samples (27.0%). All four HBoV genotypes, HBoV1 to HBoV4, were detected. HBoV2 was the most frequently detected genotype (61.8%), followed by HBoV1 (23.5%), HBoV4 (8.8%), and HBoV3 (5.9%). The highest detection rate of HBoV was observed during the warmest months in Thailand: April 2017 and March 2018. Phylogenetic analysis of VP1/VP2 nucleotide sequences of HBoV genotypes revealed that all four of the genotypes detected in environmental waters were closely related to genotypes detected in patients with acute gastroenteritis, which had been reported previously in the same geographical area. This study reports the existence of multiple HBoV genotypes in environmental waters and provides evidence of a considerably high magnitude of HBoV contamination in these waters. These findings demonstrate the potential risk of waterborne transmission of HBoV to humans. IMPORTANCE Recently, we reported the detection of HBoV genotypes 1, 2, and 3 in pediatric patients with acute gastroenteritis, and the detection of HBoV1 and 2 in oysters in Thailand. In this study, we reported the detection of HBoV1, 2, 3, and 4 contamination in environmental waters within the same geographic area. Phylogenetic analysis demonstrated that the HBoV genotypes detected in environmental waters and in oysters were closely related to HBoV detected in patients. These findings imply that HBoV contamination in oysters and in environmental waters could be a potential sources of foodborne and waterborne transmission to humans.

Automated summary

This study reported the detection of multiple HBoV genotypes in environmental waters in Thailand, with all four genotypes closely related to those detected in patients with acute gastroenteritis in the same geographical area. These findings demonstrate a considerable contamination of HBoV in environmental waters, indicating the potential risk of waterborne transmission.