Zika Virus RNA Persistence in Sewage

Despite substantial advances in knowledge and understanding about Zika virus (ZIKV), limitations in surveillance for this mainly asymptomatic infection constrain attempts to characterize the epidemiological distribution of the virus. Monitoring of fecal waste streams including sewage offers opportunities to track the spread of arboviruses such as ZIKV, known to be present in fecal waste and urine. To demonstrate the feasibility of ZIKV RNA detection in sewage, we examined viral RNA decay in sewage from a local wastewater treatment plant. We added ZIKV (MEX 1-44) to unpasteurized sewage and stored the samples at 4°C, 25°C or 35°C for one month. We extracted nucleic acids from the mixture using a QiaAmp Minelute Virus Spin Kit and measured ZIKV RNA using a TaqPath Zika Virus Kit. We found no appreciable decline in ZIKV RNA detection at 4°C during the month. We estimate that 90% decay of detectable ZIKV RNA occurred after 21 days at 25°C and after 8.5 days at 35°C. Our preliminary work suggests ZIKV RNA can remain detectable in sewage over a range of temperatures and that sewage provides a cost-effective, community diagnostic tool that deserves further investigation as a novel epidemiologic surveillance approach.