Evaluation of tomato brown rugose fruit virus as a microbial source tracking marker for human sewage in Thailand

Tomato brown rugose fruit virus (ToBRFV) has emerged as a major plant pathogen with the potential to spread through contaminated wastewater, posing risks to agriculture and public health. This study evaluated ToBRFV as a human-specific microbial source tracking (MST) marker in Thailand, comparing its performance to crAssphage. Using qPCR assays, ToBRFV was detected in 62.5 % of building sewage samples (n = 16) and 100.0 % of wastewater treatment plant (WWTP) influent samples (n = 16). Notably, ToBRFV showed minimal cross-detection in non-human fecal samples (35 pooled samples), collected from cattle, swine, chickens, ducks, and goats, with only one detection in a pig fecal-source sample, demonstrating high specificity to human sewage. Concentrations in WWTP influent were significantly higher (mean: 5.19 ± 5.05; range: 3.96–5.62 log10 copies/100 mL) than in building sewage (mean: 4.36 ± 4.40; range: 2.33–4.85 log10 copies/100 mL) (p