Environmental Surveillance for Polioviruses in Haiti (2017-2019): The Dynamic Process for the Establishment and Monitoring of Sampling Sites

Haiti is at risk for wild poliovirus (WPV) importation and circulation, as well as vaccine-derived poliovirus (VDPV) emergence. Environmental surveillance (ES) for polioviruses was established in Port au Prince and Gonaives in 2016. During 2017-2019, initial ES sites were re-evaluated, and ES was expanded into Cap Haitien and Saint Marc. Wastewater samples and data on weather, hour of collection, and sample temperature and pH were collected every 4 weeks during March 2017-December 2019 (272 sampling events) from 21 sites in Cap Haitien, Gonaives, Port au Prince, and Saint Marc. Samples were processed for the detection of polio and non-polio enteroviruses using the two-phase and Concentration and Filter Elution methodologies. Polioviruses were serotyped and underwent intra-typic characterization. No WPV or VDPVs were isolated. Sabin-like polioviruses (oral vaccine strain) of serotypes 1 and 3 were sporadically detected. Five of six (83%), one of six (17%), five of six (83%), and two of three (67%) sites evaluated in Cap Haitien, Gonaives, Port au Prince, and Saint Marc, respectively, had enterovirus isolation from >50% of sampling events; these results and considerations, such as watershed population size and overlap, influence of sea water, and excessive particulates in samples, were factors in site retention or termination. The evaluation of 21 ES sampling sites in four Haitian cities led to the termination of 11 sites. Every-four-weekly sampling continues at the remaining 10 sites across the four cities as a core Global Polio Eradication Initiative activity.

Automated summary

Haiti established environmental surveillance for polioviruses, expanding to additional cities over time. While no wild or vaccine-derived polioviruses were isolated, Sabin-like polioviruses were sporadically detected. As a result, some sampling sites were terminated based on factors like enterovirus presence and environmental considerations.