Inactivation of an Enveloped Surrogate Virus in Human Sewage

Data are needed to provide guidance for handling of human sewage potentially containing infectious Ebola virus. The purpose of this research was to determine inactivation of enveloped viruses in sewage using bacteriophage Φ6 as a surrogate. Sewage was spiked with Φ6 and held at 22 or 30 °C, and the viral titer was measured over time. Inactivation was much more rapid at 30 °C than at 22 °C. At 30 °C, inactivation was approximately linear and reached 1.7 log 10 in 24 h, 5 log 10 by 48 h, and >7 log 10 within 72 h. At 22 °C, the time to 5 log 10 inactivation was 6 days and nonlinear. In sewage, Φ6 should be considered as a potential model for survival and inactivation of enveloped human viruses. The results suggest that enveloped viruses can undergo 6–7 log inactivation in sewage in 3–7 days, depending on temperature. Longer holding times may be desirable out of an abundance of caution at lower temperatures.