BACKGROUND: Indoor human environments, including homes, offices, schools, workplaces, transport systems and other settings, often harbor potentially unsafe microorganisms. Most previous studies of bioaerosols in indoor environments have addressed contamination with bacteria or fungi. Reports on the presence of viral aerosols in indoor air are scarce, however, despite the fact that viruses are probably the most common cause of infection acquired indoor. OBJECTIVE: This review discusses the most common respiratory (influenza viruses, rhino-viruses, coronaviruses, adenoviruses, respiratory syncytial viruses, and enteroviruses) and gastrointestinal (noroviruses) viral pathogens which can be easily transmitted in indoor environments. RESULTS: The vast majority of studies reviewed here concern hospital and other health facilities where viruses are a well-known cause of occupational and nosocomial infections. Studies on other indoor environments, on the other hand, including homes, non-industrial workplaces and public buildings, are scarce. CONCLUSIONS: The lack of regulations, threshold values and standardized detection methods for viruses in indoor environments, make both research and interpretation of results difficult in this field, hampering infection control efforts. Further research will be needed to achieve a better understanding of virus survival in aerosols and on surfaces, and to elucidate the relationship between viruses and indoor environmental characteristics.

Among microorganisms, viruses are best fit to become emerging pathogens since they are able to adapt not only by mutation but also through recombination and reassortment and can thus become able to infect new hosts and to adjust to new environments. Enteric viruses are among the commonest and most hazardous waterborne pathogens, causing both sporadic and outbreak-related illness. The main health effect associated with enteric viruses is gastrointestinal illness, but they can also cause respiratory symptoms, conjunctivitis, hepatitis, central nervous system infections, and chronic diseases. Non-enteric viruses, such as respiratory and epitheliotrophic viruses are not considered waterborne, as they are not readily transmitted to water sources from infected individuals. The present review will focus on viral pathogens shown to be transmitted through water. It will also provide an overview of viruses that had not been a concern for waterborne transmission in the past, but that may represent potentially emerging waterborne pathogens due to their occurrence and persistence in water environments.

I virus sono tra i principali agenti di infezioni emergenti, in quanto sono in grado di acquisire nuove caratteristiche biologiche attraverso fenomeni di mutazione, ricombinazione e riassortimento genico, adattandosi così a nuovi ospiti e nuove nicchie ecologiche. I virus enterici sono tra le principali cause di malattie infettive di origine idrica, che possono manifestarsi come casi sporadici o cluster epidemici. Le manifestazioni cliniche più comuni sono le gastroenteriti; tuttavia i virus enterici sono in grado di causare anche sintomi respiratori, congiuntiviti, epatiti, infezioni del sistema nervoso centrale e malattie croniche. La presente rassegna fornisce una panoramica dei virus enterici tradizionalmente associati alle malattie idrotrasmesse; mostra inoltre dati epidemiologici su alcuni gruppi di virus che non sono stati associati a malattie idrodiffuse in passato (inclusi virus respiratori ed epiteliotropici), ma che possono rappresentare nuovi patogeni emergenti a causa della loro presenza e persistenza in ambienti acquatici.

This report presents a case study of a comprehensive sanitary survey on ca. 160 community drinking water supplies after a severe (post-Tsunami) flooding event in Sri Lanka. Sanitary inspection and microbiological and chemical water quality analyses were performed according to specifically-designed procedures established on the World Health Organization (WHO) guidelines. Significant hazards and critical points were identified in almost all the investigated water supplies. The overall results showed a significant level of microbiological and chemical risk associated with drinking water consumption within the investigated areas. The criteria and methods practised in this study are proposed as a model to assure an effective and reliable monitoring in post-emergencies involving possible deterioration of water quality and to identify health priorities related to water consumption.

Viene riportato un caso studio relativo alla sorveglianza sanitaria di circa 160 fonti di approvvigionamento di acqua potabile dopo il maremoto che ha interessato lo Sri Lanka. In accordo con una specifica procedura elaborata sulla base delle linee guida dell'Organizzazione Mondiale della Sanità (OMS), sono state effettuate ispezioni sanitarie e analisi sulla qualità microbiologica e chimica dell'acqua. In quasi tutti gli approvvigionamenti idrici controllati sono stati identificati pericoli significativi e punti critici. I risultati mostrano un significativo livello di rischio microbiologico e chimico associato all'uso di acqua potabile nelle aree investigate. I criteri e i metodi utilizzati in questo studio sono proposti come modello per ottenere un pratico ed efficace monitoraggio in condizioni di post-emergenza che possono portare al deterioramento della qualità delle acque ed identificare priorità sanitarie correlate al consumo di acqua potabile.

Data on the occurrence of non-tuberculous mycobacteria (NTM), in parallel with those obtained for bacterial indicators and amoebae, are presented with the aim to collect information on the spread of NTM in drinking water distribution systems in Italy. Samples were collected from taps of hospitals and households in Central and Southern Italy. The concentration values obtained for the more traditional microbial parameters complied with the mandatory requirements for drinking water. Conversely, moderate-to-high microbial loads (till 300 CFU/L) were observed for the NTM. Positive samples were obtained from 62% of the investigated water samples. Analogous results were observed for amoebae showing a higher percentage of positive samples (76%). In terms of public health, the presence of mycobacteria in water distribution systems may represent a potential risk especially for vulnerable people such as children, the elderly or immunocompromised individuals.

Per la prima volta in Italia, acqua potabile distribuita in rete è stata analizzata per verificare l'eventuale presenza di micobatteri non tubercolari (NTM). I microrganismi sono stati ricercati in acque di rubinetto prelevate da ospedali e da abitazioni del Centro e del Sud Italia; parallelamente, oltre ai tradizionali indicatori microbici di contaminazione e di qualità dell'acqua, i campioni sono stati esaminati per la presenza di amebe. Con specifico riferimento agli indicatori, quali parametri di monitoraggio delle acque, le analisi hanno evidenziato la rispondenza ai requisiti di qualità stabiliti per le acque potabili. Diversamente, per i micobatteri sono state rilevate densità variabili, anche piuttosto elevate (fino a 300 UFC/L), con una percentuale di positività del 62% nei campioni di acqua esaminati; valori di positività più elevati (76%) sono risultati per le amebe. In termini di salute pubblica, la presenza di NTM nelle reti di distribuzione idrica può costituire una condizione di rischio, soprattutto per le fasce di popolazione più suscettibili (immunodepressi, bambini e anziani).