Haiti Poliovirus Environmental Surveillance

Abstract

Poliovirus (PV) environmental surveillance was established in Haiti in three sites each in Port-au-Prince and Gonaïves, where sewage and fecal-influenced environmental open water channel samples were collected monthly from March 2016 to February 2017. The primary objective was to monitor for the emergence of vaccine-derived polioviruses (VDPVs) and the importation and transmission of wild polioviruses (WPVs). A secondary objective was to compare two environmental sample processing methods, the gold standard two-phase separation method and a filter method (bag-mediated filtration system [BMFS]). In addition, non-polio enteroviruses (NPEVs) were characterized by next-generation sequencing using Illumina MiSeq to provide insight on surrogates for PVs. No WPVs or VDPVs were detected at any site with either concentration method. Sabin (vaccine) strain PV type 2 and Sabin strain PV type 1 were found in Port-au-Prince, in March and April samples, respectively. Non-polio enteroviruses were isolated in 75-100% and 0-58% of samples, by either processing method during the reporting period in Port-au-Prince and Gonaïves, respectively. Further analysis of 24 paired Port-au-Prince samples confirmed the detection of a human NPEV and echovirus types E-3, E-6, E-7, E-11, E-19, E-20, and E-29. The comparison of the BMFS filtration method to the two-phase separation method found no significant difference in sensitivity between the two methods (mid-P-value = 0.55). The experience of one calendar year of sampling has informed the appropriateness of the initially chosen sampling sites, importance of an adequate PV surrogate, and robustness of two processing methods.

Figure 1.

Haiti poliovirus environmental surveillance sampling sites from March 2016 to February 2017 and associated geographical and estimated population data: (A) Haiti and the cities of Port-au-Prince and Gonaïves; (B) sampling sites in Port-au-Prince: MAC = Morne á Cabri, BNF = Bois Neuf, and BDC = Bois de Chêne; and (C) sampling sites in Gonaïves: KSB = Key Soleil Bridge, KHF = Key Soleil Health Facility, and ATP = Authorité Portuaire. Watersheds for each sampling site are indicated in green shading, except for ATP and MAC where the watershed boundaries could not be determined.

Figure 2.

Water quality analysis from sites in Gonaïves and Port-au-Prince with illustrated physicochemical parameters and Escherichia coli concentrations for months when the data were collected (Morne à Cabri data not shown). EC = E. coli; ATP = Autorité Portuaire; KHF = Key Soleil Health Facility; KSB = Key Soleil Bridge; BDC = Bois de Chêne; BNF = Bois Neuf; TDS = total dissolved solids; ppm = parts per million; NTU = nephelometric turbidity unit.

Figure 3.

Enteroviruses isolated during March 2016 to February 2017 from six environmental surveillance sites in Haiti. No wild or vaccine-derived polioviruses were isolated. The brackets note the time period of a national mass vaccination campaign with trivalent oral poliovirus vaccine (types 1, 2, and 3) targeting children aged 0–59 months. T = two-phase separation method; B = bag-mediated filtration system; NEV = non-enterovirus; NPEV = non-polio enterovirus; SL1 = Sabin-like 1; SL2 = Sabin-like 2. ATP = Autorité Portuaire; KHF = Key Soleil Health Facility; KSB = Key Soleil Bridge; BDC = Bois de Chêne; BNF = Bois Neuf; MAC = Morne á Cabri.

Figure 4.

Enterovirus VP1 phylogeny of viruses detected through environmental surveillance in Haiti using two different processing methods. Sequences obtained from viruses isolated after the bag-mediated filtration system are listed in red text, and after the two-phase separation method are listed in blue text. Representative GenBank references are listed in black text. A broad-perspective tree is displayed on the top left, whereas the detailed clade-level trees present NPEV sequence accession number, type, and strain name. CV = Coxsackievirus; EV = Enterovirus; E = Echovirus; PV = Poliovirus.