A Model-Based Framework to Assess the Feasibility of Monitoring Zika Virus with Wastewater-Based Epidemiology

Wastewater-based epidemiology (WBE) is a promising community-level monitoring technique used for tracking diseases with well-documented enteric transmission or shedding. However, it is less clear if WBE is feasible for monitoring vector-borne pathogens like Zika virus. Using Monte Carlo simulation, the distributions for (i) total Zika RNA shedding from infected individuals and (ii) the process limit of detection (PLOD) were generated, and the probability of detecting Zika RNA in wastewater per infection rate was calculated. Urine drives Zika RNA shedding, leading to a median total shedding of 6.73 log 10 genome copies (GC)/day. At a PLOD of 1.16 log 10 GC/L, an infection rate of 0.11% (single PCR replicate) is required for 50% probability of detection, based on typical U.S. wastewater treatment plant (WWTP) flows. From historical case data, successful Zika WBE application is unlikely in the United States but likely for Zika-endemic countries with decreased WWTP per capita flows, like Brazil and Colombia, during an outbreak as observed in 2016. The great discrepancy between true and reported clinical cases, however, suggests that Zika WBE for endemic countries may be feasible even in the absence of outbreaks. Finally, we identify future work necessary for improved assessment of Zika WBE applications.