Molecular detection and characterization of human bocavirus in environmental waters in Thailand from 2020 to 2022

Human bocavirus (HBoV) is a globally recognized pathogen associated with respiratory and gastrointestinal infections in infants and young children. Its detection in both clinical and environmental water samples has raised concerns about potential waterborne transmission. This study investigated the prevalence and genetic diversity of HBoV in environmental water sources in Chang Mai, Thailand, from July 2020 to December 2022. A total of 600 water samples from various environmental sources were analyzed using PCR assay. Nucleotide sequencing and phylogenetic analysis were performed to identify HBoV genotypes and assess their genetic characteristics. HBoV was detected in 32 of 600 samples (5.3 %), representing a notable decline in the detection rates during the COVID-19 pandemic. Among the sample types, wastewater showed highest detection rate (23.3 %), followed by irrigation water (1.2 %), and river water (0.8 %). No HBoV was detected in environmental reservoir water samples. All four known HBoV genotypes (HBoV1-HBoV4) were identified, with HBoV2 being the most prevalent genotype (19 strains; 59.4 %), followed by HBoV3 (6 strains; 18.8 %), HBoV1 (5 strains; 15.6 %), and HBoV4 (2 strains; 6.2 %). No clear seasonal pattern of HBoV contamination was observed. Phylogenetic analysis revealed a close genetic relationship between environmental and human-associated HBoV strains, suggesting an interactive transmission of HBoV between human and the environment. This study highlights the prevalence and genetic diversity of HBoV in environmental waters during the COVID-19 pandemic and underscores the need for continued surveillance to a better understanding its environmental dynamics and potential public health implications.