Inferring Numbers of Wild Poliovirus Excretors Using Quantitative Environmental Surveillance

Abstract

Response to and monitoring of viral outbreaks can be efficiently focused when rapid, quantitative, kinetic information provides the location and the number of infected individuals. Environmental surveillance traditionally provides information on location of populations with contagious, infected individuals since infectious poliovirus is excreted whether infections are asymptomatic or symptomatic. Here, we describe development of rapid (1 week turnaround time, TAT), quantitative RT-PCR of poliovirus RNA extracted directly from concentrated environmental surveillance samples to infer the number of infected individuals excreting poliovirus. The quantitation method was validated using data from vaccination with bivalent oral polio vaccine (bOPV). The method was then applied to infer the weekly number of excreters in a large, sustained, asymptomatic outbreak of wild type 1 poliovirus in Israel (2013) in a population where >90% of the individuals received three doses of inactivated polio vaccine (IPV). Evidence-based intervention strategies were based on the short TAT for direct quantitative detection. Furthermore, a TAT shorter than the duration of poliovirus excretion allowed resampling of infected individuals. Finally, the method documented absence of infections after successful intervention of the asymptomatic outbreak. The methodologies described here can be applied to outbreaks of other excreted viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), where there are (1) significant numbers of asymptomatic infections; (2) long incubation times during which infectious virus is excreted; and (3) limited resources, facilities, and manpower that restrict the number of individuals who can be tested and re-tested.

The role of time-varying viral shedding in modelling environmental surveillance for public health: revisiting the 2013 poliovirus outbreak in Israel

“…A promising indirect approach to account for sewage dilution volume is to use a molecular marker correlated with wastewater strength as a normalizing factor for the pathogen concentration [56]. Another promising approach to estimate the number of infected individuals is to model the series of processes between excretion and detection with statistics distributions [59]. While our work is an important step in the direction of maximizing the potential of environmental surveillance, ultimately collaboration between wastewater engineers, pathogen specialists and modellers will be needed to make environmental surveillance truly useful.…”

Re‐Emergence of Poliovirus in the United States: Considerations and Implications

“…7 Environmental surveillance is a key component to detecting poliovirus circulation in the absence of confirmed paralytic poliomyelitis cases, and as such, it is a central component of the current poliovirus response in New York. 14 Although AFP surveillance is commonly conducted in many countries still at risk for ongoing transmission of poliovirus, AFP is not a component of standardized syndromic surveillance in the US. In contrast, AFM, which is characterized by rapid onset of flaccid weakness in one or more limbs and neuroimaging findings of distinct abnormalities of the spinal cord gray matter on magnetic resonance imaging, is a nationally reportable condition.…”

“…Diagnostic confirmation is performed through stool specimens in accredited laboratories, and through environmental surveillance of sewage 7 . Environmental surveillance is a key component to detecting poliovirus circulation in the absence of confirmed paralytic poliomyelitis cases, and as such, it is a central component of the current poliovirus response in New York 14 …”

Prevalence of Non-Polio Enteroviruses in the Sewage of Guangzhou City, China, from 2013 to 2021

“…Importantly, most EV infections are non-symptomatic; therefore, it is difficult to track all EV infections through case surveillance systems. Owing to this, EV environmental surveillance was developed because it can find the “hidden” circulating EV serotypes in the community: this can be used as an important supplement to the EV disease surveillance system ( 14 – 17 ).…”