Human Bocavirus: Detection, Quantification and Molecular Characterization in Sewage and Surface Waters in Uruguay

Human bocavirus (HBoV) infections are related to respiratory and gastroenteric diseases. The aim of this study was to investigate the presence of HBoV in both sewage and surface waters in Uruguay. Sixty-eight sewage samples from the cities of Salto, Paysandú, Bella Unión, Fray Bentos, Treinta y Tres and Melo and 36 surface water samples from the cities of Salto, Florida and Santa Lucía were studied. HBoV was screened by multiplex qPCR for the detection of the four subtypes, followed by monoplex qPCRs for the independent quantification of each subtype. A qualitative PCR followed by DNA sequencing and phylogenetic analysis was carried out for molecular characterization of HBoV strains. HBoV was present in a high frequency (69%) in sewage and only one positive sample (3%) was found in surface water. Concerning sewage samples, HBoV1 was detected in 11 (23%) out of the 47 positives samples, with a mean concentration of 8.2 × 10⁴ genomic copies/Liter (gc/L), HBoV3 was detected in 35 (74%) of the positive samples with a mean concentration of 4.1 × 10⁶ gc/L and subtypes 2 and/or 4 were detected in 39 (83%) of the positive samples with a mean concentration of 7.8 × 10⁶ gc/L. After the phylogenetic analysis performed by a Bayesian approach, the four HBoV subtypes were confirmed. This is the first study determining a high frequency of HBoV and the presence of the four HBoV subtypes in aquatic matrices in Latin America, mainly in sewage. Although HBoV was scarcely detected in surface water, a waterborne transmission is likely to occur if people enter in contact with polluted surface waters for recreational activities such as fishing or swimming since an elevated frequency of HBoV was detected in raw sewage which is usually directly discharged into surface waters.