Environmental Surveillance for Polioviruses in the Global Polio Eradication Initiative

Abstract

This article summarizes the status of environmental surveillance (ES) used by the Global Polio Eradication Initiative, provides the rationale for ES, gives examples of ES methods and findings, and summarizes how these data are used to achieve poliovirus eradication. ES complements clinical acute flaccid paralysis (AFP) surveillance for possible polio cases. ES detects poliovirus circulation in environmental sewage and is used to monitor transmission in communities. If detected, the genetic sequences of polioviruses isolated from ES are compared with those of isolates from clinical cases to evaluate the relationships among viruses. To evaluate poliovirus transmission, ES programs must be developed in a manner that is sensitive, with sufficiently frequent sampling, appropriate isolation methods, and specifically targeted sampling sites in locations at highest risk for poliovirus transmission. After poliovirus ceased to be detected in human cases, ES documented the absence of endemic WPV transmission and detected imported WPV. ES provides valuable information, particularly in high-density populations where AFP surveillance is of poor quality, persistent virus circulation is suspected, or frequent virus reintroduction is perceived. Given the benefits of ES, GPEI plans to continue and expand ES as part of its strategic plan and as a supplement to AFP surveillance.

Polio Eradication in Bangladesh: Evaluation of AFP Surveillance Indicators, 2011-2015

“…Researches suggest that Environmental Poliovirus Surveillance (ENV) should be in place during the period between interruption of wild poliovirus (WPV) transmission & certification of eradication and should be continued into the post eradication phase and OPV cessation period to monitor emergence of Vaccine Derived Poliovirus (VDPV) re-emergence of WPV or disappearance of all OPV-related strains [26]. There is also evidence that ENV along with routine AFP case based surveillance is more effective to detect introduction and circulation of Wild Poliovirus (WPV) and Vaccine Derived Poliovirus (VDPV) [27][28][29][30][31]. Environmental surveillance also has a role in new WHO strategy for intensified effort to complete poliomyelitis eradication [32] and can be useful to monitor the efficacy of immunisation initiatives when necessary [26].…”

Estimated Effect of Inactivated Poliovirus Vaccine Campaigns, Nigeria and Pakistan, January 2014–April 2016

“…We analyzed polio vaccination data reported from Nigeria and Pakistan during January 1, 2014–April 30, 2016, by combining information on the dates and locations (districts) of vaccination campaigns, the district-level incidence of poliomyelitis reported through surveillance for acute flaccid paralysis, and the presence or absence of poliovirus in environmental samples collected at regular intervals (weekly, every 2 weeks, or monthly) from wastewater/sewage channels that flow out of areas of interest for environmental surveillance ( 14 ). We obtained the data on July 11, 2016, from PolIS (the Polio Information System), which collects poliovirus-associated data and information, including surveillance data, from different sources for the World Health Organization (WHO) and its partners.…”

Surveillance Systems to Track Progress Toward Polio Eradication — Worldwide, 2014–2015

“…Testing of sewage samples supplements AFP surveillance by identifying poliovirus transmission that might occur in the absence of detected AFP cases (6 …”