Wastewater-based epidemiology (WBE) is an approach with the potential to complement clinical surveillance systems. Using WBE, it is possible to carry out an early warning of a possible outbreak, monitor spatial and temporal trends of infectious diseases, produce real-time results and generate representative epidemiological information in a territory, especially in areas of social vulnerability. Despite the historical uses of this approach, particularly in the Global Polio Eradication Initiative, and for other pathogens, it was during the COVID-19 pandemic that occurred an exponential increase in environmental surveillance programs for SARS-CoV-2 in wastewater, with many experiences and developments in the field of public health using data for decision making and prioritizing actions to control the pandemic. In Latin America, WBE was applied in heterogeneous contexts and with emphasis on populations that present many socio-environmental inequalities, a condition shared by all Latin American countries. This manuscript addresses the concepts and applications of WBE in public health actions, as well as different experiences in Latin American countries, and discusses a model to implement this surveillance system at the local or national level. We emphasize the need to implement this sentinel surveillance system in countries that want to detect the early entry and spread of new pathogens and monitor outbreaks or epidemics of infectious agents in their territories as a complement of public health surveillance systems.

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.

In Haiti, measles, rubella, and maternal and neonatal tetanus have been eliminated, but a diphtheria outbreak is ongoing as of 2019. We conducted a national representative, household-based, two-stage cluster survey among children aged 5–7 years in 2017 to assess progress toward maintenance of control and elimination of selected vaccine-preventable diseases (VPDs). We stratified Haiti into west region (west department, including the capital city) and non-west region (all other departments). We obtained vaccination history and dried blood spots, and measured antibody concentrations to VPDs on a multiplex bead assay. Among 1,146 children, national seropositivity was 83% (95% CI: 80–86%) for tetanus, 83% (95% CI: 81–85%) for diphtheria, 87% (95% CI: 85–89%) for measles, and 84% (95% CI: 81–87%) for rubella. None of the children had long-term immunity to tetanus or diphtheria (IgG concentration ≥ 1 international unit/mL). Seropositivity in the west region was lower than that in the non-west region. Vaccination coverage was 68% (95% CI: 61–74%) for ≥ 3 doses of tetanus- and diphtheria-containing vaccine (DTP3), 84% (95% CI: 80–87%) for one dose of measles–rubella (MR1) vaccine, and 20% (95% CI: 16–24%) for MR2. The seroprevalence of measles, rubella, and diphtheria antibodies is lower than population immunity levels needed to prevent disease transmission, particularly in the west region; reintroduction of these diseases could lead to an outbreak. To maintain VPD control and elimination, Haiti should achieve DTP3 and MR2 coverage ≥ 95%, and include tetanus and diphtheria booster doses in the routine immunization schedule.

In 2016, the World Health Assembly endorsed the Global Health Sector Strategy on Viral Hepatitis, which calls for elimination of hepatitis B virus (HBV) by 2030 (definition: ≤ 0.1% hepatitis B surface antigen [HBsAg] prevalence among children aged 5 years). The burden of chronic HBV infection among children in Haiti is unknown. We conducted a nationally representative cross-sectional serological survey among 5- to 7-year-old children based on a two-stage cluster design with two strata: West (includes metropolitan Port-au-Prince) and non-West (all other departments). We collected demographic, socioeconomic, and vaccination history data and tested for HBsAg using a rapid point-of-care test. We estimated HBsAg prevalence and evaluated the association of HBV infection with vaccination history, demographics, and socioeconomic characteristics. Of the 1,152 children, seven (0.5%, 95% CI: 0.2–1.2) were HBsAg positive. The HBsAg prevalence varied by region (West: 0.1%, 95% CI: 0.01–0.9; non-West: 0.7%, 95% CI: 0.2–1.9) (P = 0.1), gender (males: 0.7%, 95% CI: 0.2–2.4; females: 0.2%, 95% CI: 0.05–1.1) (P = 0.3), and caregiver’s education level (none: 0.8%, 95% CI: 0.2–3.1; some or completed primary: 0.5%, 95% CI: 0.1–1.8; some secondary: 0.4%, 95% CI: 0.1–1.8; secondary and higher: 0.0%, 95% CI: 0–0), although the differences were not statistically significant. None of the HBsAg-positive children had documented vaccination with hepatitis B vaccine (HepB). Haiti’s chronic HBV infection prevalence among children is low; however, it is above the elimination target. To reach elimination, Haiti needs to achieve high coverage with the three HepB doses and introduce a HepB birth dose.

With 762 laboratories, the Global Measles and Rubella Laboratory Network (GMRLN) is the largest laboratory network coordinated by the World Health Organization (WHO). Like the Global Polio Laboratory Network, the GMRLN has multiple tiers, including global specialized laboratories, regional reference laboratories, national laboratories, and, in some countries, subnational laboratories. Regional networks are supervised by regional laboratory coordinators reporting to a global coordinator at WHO headquarters. Laboratories in the GMRLN have strong links to national disease control and vaccination programs. The GMRLN’s goal is to support member states in obtaining timely, complete, and reliable laboratory-based surveillance data for measles and rubella as part of the strategy for achieving measles and rubella elimination. Surveillance data are reported to the national program and are included in annual reports on the status of measles and rubella elimination to national verification committees for review by regional verification commissions. Quality within the GMRLN is ensured by monitoring performance through external quality assurance programs, confirmatory and quality control testing, accreditation, and coordination of corrective action and training where needed. The overall performance of the laboratories has remained high over the years despite many challenges, particularly the COVID-19 pandemic. The GMRLN is well-positioned to support high-quality laboratory-based surveillance for measles and rubella and to transition to supporting laboratory testing for other pathogens, including vaccine-preventable diseases.

This report reviews national data from all Member States on measles, rubella, and congenital rubella syndrome (CRS) elimination in the Region of the Americas during 2019–2023. It includes an analysis of compliance with vaccination coverage, surveillance indicators, and measles outbreaks, as well as an analysis of the response capacity of the laboratory network and a country case study that meets all indicators. The sources of information were the integrated epidemiological surveillance system for measles and rubella of the Pan American Health Organization (PAHO)/World Health Organization (WHO) and the Joint Reporting Form (eJRF), among others. From 2020 to 2022, regional coverage with first (MMR-1) and second doses (MMR-2) decreased to rates below 90%. The regional suspected case notification rate was maintained above the minimum expected 2.0 suspect cases per 100,000 population, except in 2021. During 2019 to 2023, 18 countries experienced outbreaks, with two of the outbreaks resulting in re-established endemic transmission. In conclusion, two countries in the Americas have not maintained measles elimination, but by the end of 2023 no country showed endemic measles transmission. One of the countries that lost its certification of elimination in 2018 managed to be reverified in 2023; the other is pending reverification. All countries maintained rubella elimination. Despite these challenges, the sustainability of the elimination of these diseases remains a health priority in the Region.