Torque Teno Virus Occurrence and Relationship to Bacterial and Viral Indicators in Feces, Wastewaters, and Waters in the United States

Abstract

Indicator organisms are used to assess pathogen risk in waters, however, indicators often do not correlate with pathogens. Direct pathogen monitoring (e.g., human adenoviruses) may provide data on actual risk from one pathogen but may not be indicative of overall risk. A potential alternative indicator is Torque teno virus (TTV), which may co-locate with pathogenic enteric viruses but has not been associated with any disease. The objective of this research was to determine the value of TTV as a potential indicator of human fecal contamination and viral pathogen risk in the United States. Occurrence of TTV in animal feces, wastewaters, and drinking waters was evaluated by polymerase chain reaction with primers in the highly conserved untranscribed region to detect TTV human genotypes. These data were compared to data on standard indicators and human adenovirus presence. TTV was detected in 4.0% of animal feces, 41.7% of wastewater samples, and 13.9% of drinking water samples. These relatively low positive rates in waters may reflect the relatively low prevalence of serum TTV positivity in the United States. Adenoviruses were detected in a larger percentage (83.3%) of wastewaters (indicative of human fecal contamination) than TTV, and analysis of nonhuman animal feces showed the human adenovirus assay to have a higher degree of specificity. This study adds to the understanding of the global occurrence of TTV. Based on a lack of correlation with fecal indicators and varying prevalence rates in humans, TTV does not appear to be a suitable indicator of fecal contamination.