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

Abstract

Haïti 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 Gonaïves in 2016. During 2017-2019, initial ES sites were re-evaluated, and ES was expanded into Cap Haïtien 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 Haïtien, Gonaïves, 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 Haïtien, Gonaïves, 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 Haïtian 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.

Keywords: enterovirus; environmental surveillance; polio eradication; vaccine-derived polioviruses; wild poliovirus.

Figure 1

Haïti poliovirus environmental surveillance sites during March 2017–December 2019, site locations. (A) Location of the cities of Cap Haïtien, Gonaïves, Port au Prince, and Saint Marc. Poliovirus environmental surveillance sampling sites in (B) Port au Prince (BDC = Bois de Chêne, BNF = Bois de Neuf, CAC = Cite au Cayes, CAR = Carrefour, and RRD = Route Rails Diquini; the MAC site is not shown [17]); (C) Gonaïves: (ALL = Avenue Leon Legros, ATP = Autorité Portuaire, BRA = Boulevard de l’Avenir, KHF = Key Soleil Health Facility, KHS = Key Soleil School, and KSB = Key Soleil Bridge); (D) Saint Marc (AMA = Avenue Maurepas, HUC = Impasse Hucar, and PET = Rue Petion); (E) Cap Haïtien (RNB = Route National Bridge); and (F) Cap Haïtien (CRC = Ruelle Caporis, GRC = Grand Rue Champin, IMP = Impasse Petion, CMB = Rivière Commerce Bridge, and RPA = Ruelle Patience). Watershed boundaries for each sampling site are indicated in green shading, except for ATP, where the boundaries could not be determined [17,24].

Figure 2

Enteroviruses isolated through Haïti poliovirus environmental surveillance during March 2017–December 2019 by year, epidemiological week, and sampling site. Orange shading for months in 2018 and May 2019 indicates periods of tetanus–diphtheria outbreak response campaigns in certain regions, which provided an opportunity for intensified all-antigen vaccination, and for July–September 2019 indicates the approximate time period of a nationwide supplementary immunization activity targeting children 2–59 months of age with bivalent oral polio vaccine (bOPV, containing Sabin strain serotypes 1 and 3). NPEV = non-polio enterovirus; SL1 = Sabin-like poliovirus of serotype 1; SL3 = Sabin-like poliovirus of serotype 3.