Wastewater-based surveillance represents a non-invasive approach to monitor pathogen circulation, but data on cruise ships are scarce, although this enclosed environment is prone to infectious diseases spreading. We conducted a pilot study in a Mediterranean seaport (Italy) between July and October 2024, combining wastewater monitoring with onboard clinical surveillance. Twenty wastewater samples (10 untreated and 10 treated) were collected from 10 cruise ships. Viral detection targeted 10 human respiratory and gastrointestinal viruses. Bacterial and viral indicators (total coliform, Escherichia coli, intestinal enterococci, and somatic coliphages) were analyzed to evaluate wastewater treatment performance. Aggregated clinical data were extracted from medical reports and categorized using ICD-10 codes for symptoms of likely infectious viral origin. Norovirus genogroup II was consistently detected in untreated sewage (100%), followed by SARS-CoV-2 (60%), human adenovirus (30%), enterovirus, rotavirus, and hepatitis E virus (10–20%). Viral loads decreased in treated samples, although wastewater treatment efficiency varied widely among vessels: some ships exhibited a logarithmic abatement of less than 2 log10 units, with effluents showing microbiological concentrations above the thermotolerant coliform benchmark established for sewage treatment plant certification by the International Maritime Organization (IMO) guidelines. Clinical surveillance recorded more respiratory than gastrointestinal cases, with COVID-19 and influenza confirmed in several arrivals. The integration of environmental and clinical data provided complementary insights, particularly for SARS-CoV-2 detection in wastewater, which occurred in around 85% of ship arrivals with clinically diagnosed COVID-19 cases. These findings demonstrate that wastewater monitoring can complement clinical surveillance on cruise ships, by offering information on viral circulation. The variability observed in treatment efficacy underscores the need for harmonized standards and supports the inclusion of wastewater monitoring in maritime preparedness and resilience strategies to strengthen public health security against emerging infectious threats and enhance system adaptability to future outbreaks.
“Navigating Healthy Waters”: monitoring ship wastewater as a key defense against infectious diseases—a pilot study on a Mediterranean seaport
Federigi, IleanaPrimo
;Zotti, NunzioSecondo
;Pellegrini, Marzia;Verani, Marco;Pagani, Alessandra;Carducci, Annalaura;Rizzo, Caterina
Ultimo
2026-01-01
Abstract
Wastewater-based surveillance represents a non-invasive approach to monitor pathogen circulation, but data on cruise ships are scarce, although this enclosed environment is prone to infectious diseases spreading. We conducted a pilot study in a Mediterranean seaport (Italy) between July and October 2024, combining wastewater monitoring with onboard clinical surveillance. Twenty wastewater samples (10 untreated and 10 treated) were collected from 10 cruise ships. Viral detection targeted 10 human respiratory and gastrointestinal viruses. Bacterial and viral indicators (total coliform, Escherichia coli, intestinal enterococci, and somatic coliphages) were analyzed to evaluate wastewater treatment performance. Aggregated clinical data were extracted from medical reports and categorized using ICD-10 codes for symptoms of likely infectious viral origin. Norovirus genogroup II was consistently detected in untreated sewage (100%), followed by SARS-CoV-2 (60%), human adenovirus (30%), enterovirus, rotavirus, and hepatitis E virus (10–20%). Viral loads decreased in treated samples, although wastewater treatment efficiency varied widely among vessels: some ships exhibited a logarithmic abatement of less than 2 log10 units, with effluents showing microbiological concentrations above the thermotolerant coliform benchmark established for sewage treatment plant certification by the International Maritime Organization (IMO) guidelines. Clinical surveillance recorded more respiratory than gastrointestinal cases, with COVID-19 and influenza confirmed in several arrivals. The integration of environmental and clinical data provided complementary insights, particularly for SARS-CoV-2 detection in wastewater, which occurred in around 85% of ship arrivals with clinically diagnosed COVID-19 cases. These findings demonstrate that wastewater monitoring can complement clinical surveillance on cruise ships, by offering information on viral circulation. The variability observed in treatment efficacy underscores the need for harmonized standards and supports the inclusion of wastewater monitoring in maritime preparedness and resilience strategies to strengthen public health security against emerging infectious threats and enhance system adaptability to future outbreaks.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
