Viral persistence in source-separated human urine

Abstract

Urine separating sewerage systems have been promoted since urine contributes the major amounts of nitrogen (80%) and phosphorous (55%) to household wastewater, while only constituting 1% of the volume. To evaluate potential health risks from enteric viruses in stored urine used in agriculture, source-separated urine (pH 9) was challenged with rhesus rotavirus and Salmonella typhimurium phage 28B and their persistence followed over time. No significant inactivation of either rotavirus or the phage occurred at 5°C during 6 months of storage, while the mean T 90 values at 20°C were estimated at 35 and 71 days for rotavirus and the phage, respectively. In pH controls (pH 7), the inactivation of rotavirus was similar to that in urine at both temperatures, whereas no decay of the phage occurred at either 5 or 20°C. Therefore, rotavirus inactivation appeared to be largely temperature-dependent, whereas there was an additional virucidal effect on the phage in urine at 20°C (pH 9). Hence, risks from enteric viruses are likely to be dictated by the proportion of faecal cross-contamination and the urine storage time and temperature. If stored at 20°C for at least 6 months, urine may be considered safe to use as a fertilizer for any crop.