Survival of surrogate coronaviruses in water

Abstract

The emergence of a previously unknown coronavirus infection, Severe Acute Respiratory Syndrome (SARS), demonstrated that fecally contaminated liquid droplets are a potential vehicle for the spread of a respiratory virus to large numbers of people. To assess potential risks from this pathway, there is a need for surrogates for SARS coronavirus to provide representative data on viral survival in contaminated water. This study evaluated survival of two surrogate coronaviruses, transmissible gastroenteritis (TGEV) and mouse hepatitis (MHV). These viruses remained infectious in water and sewage for days to weeks. At 25 degrees C, time required for 99% reduction in reagent-grade water was 22 days for TGEV and 17 days for MHV. In pasteurized settled sewage, times for 99% reduction were 9 days for TGEV and 7 days for MHV. At 4 degrees C, there was <1 log(10) infectivity decrease for both viruses after four weeks. Coronaviruses can remain infectious for long periods in water and pasteurized settled sewage, suggesting contaminated water is a potential vehicle for human exposure if aerosols are generated.

Fig. 1

(a) Infectivity of TGEV (time 0 titer 4.5 log₁₀ MPN/mL) and MHV (time 0 titer 6.5 log₁₀ MPN/mL) over 49 days in reagent-grade water at 25 °C, 4 trials per point. Observed data = points; predicted values from regression analysis = lines (gray squares and lines = TGEV; black circles and lines = MHV; dashed line = TGEV detection limit). (b) Infectivity of TGEV (time 0 titer 4.8 log₁₀ MPN/mL) and MHV (time 0 titer 6.5 log₁₀ MPN/mL) over 49 days in reagent-grade water at 4 °C, 4 trials per point. Observed data = points; predicted values from regression analysis = lines (gray squares and lines = TGEV; black circles and lines = MHV).

Fig. 2

(a) Infectivity of TGEV (time 0 titer 5.0 log₁₀ MPN/mL) and MHV (time 0 titer 6.9 log₁₀ MPN/mL) over 14 days in lake water at 25 °C, 4 trials per point (gray squares and lines = TGEV; black circles and lines = MHV). (b) Infectivity of TGEV (time 0 titer 5.2 log₁₀ MPN/mL) and MHV (time 0 titer 6.6 log₁₀ MPN/mL) over 14 days in lake water at 4 °C, 4 trials per point (gray squares and lines = TGEV; black circles and lines = MHV).

Fig. 3

(a) Infectivity of TGEV (time 0 titer 5.8 log₁₀ MPN/mL) and MHV (time 0 titer 6.6 log₁₀ MPN/mL) over 21 days in pasteurized settled sewage at 25 °C, 4 trials per point. Observed data = points; predicted values from regression analysis = lines (gray squares and lines = TGEV; black circles and lines = MHV; dashed line = MHV detection limit). (b) Infectivity of TGEV (time 0 titer 5.5 log₁₀ MPN/mL) and MHV (time 0 titer 6.8 log₁₀ MPN/mL) over 35 days in pasteurized settled sewage at 4 °C, 4 trials per point. Observed data = points; predicted values from regression analysis = lines (gray squares and lines = TGEV; black circles and lines = MHV).