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.

Hepatitis A is a viral disease with a significant public health impact, especially in developing countries. Improvements in sewage services could prevent hepatitis A virus (HAV) dissemination into the environment and minimize the risk of infection. The aim of this study was to monitor HAV for one year in urban sewage samples from the largest wastewater treatment plant in Rio de Janeiro, Brazil, to assess environmental contamination with HAV and its dissemination after treatment by an activated sludge process. For this purpose, 48 samples (24 raw sewage samples and 24 treated effluent samples) were collected from August 2009 to July 2010 for HAV detection. Using quantitative real-time PCR 14 (58%) raw sewage samples were positive for HAV, and the highest viral genome loads were detected in the spring and summer. HAV was not detected in treated effluent samples, which suggests that the viral loads observed could be easily removed by the activated sludge process, thus preventing the dissemination of HAV into the environment. All of the HAV strains sequenced belonged to subgenotype IA, which clustered closely with Brazilian and Argentine HAV strains. These data demonstrate that environmental monitoring can be a useful tool in epidemiological studies.

Human enteric viruses are responsible to cause several diseases, including gastroenteritis and hepatitis, and can be present in high amounts in sewage sludge. This study compared virus recovery efficiency of two feasible concentration methods used for detecting human adenovirus (HAdV), rotavirus species A (RV-A), norovirus genogroup II (NoV GII) and hepatitis A virus (HAV) in sewage sludge from an activated sludge process. Twelve sewage sludge samples were collected bi-monthly from January to July, 2011. Ultracentrifugation was compared with a simplified protocol based on beef extract elution for recovering enteric viruses. Viruses were quantified by quantitative real-time PCR assays and virus recovery efficiency and limits of detection were determined. Methods showed mean recovery rates lower than 7.5%, presenting critical limits of detection (higher than 10² 10³ genome copies -GC L-1 for all viruses analyzed). Nevertheless, HAdV were detected in 90% of the analyzed sewage sludge samples (range: 1.8 x 10(4) to 1.1 x 10(5) GC L-1), followed by RV-A and NoV (both in 50%) and HAV (8%). Results suggesting that activated sludge is contaminated with high viral loads and HAdV are widely disseminated in these samples. The low virus recovery rates achieved, especially for HAV, indicate that other feasible concentration methods could be developed to improve virus recovery efficiency in these environmental matrices.