Enteric viruses in recreational waters in the Province of Salta, Argentina: Quantitative Microbial Risk Assessment

HUGO R. POMA; DOLORES GUTIÉRREZ CACCIABUE; VERÓNICA RAJAL

Florianópolis

Congreso; 17th International Symposium on Health related Water-Watermicro 2013; 2013

International Water Association (IWA)

Incidences of diarrheal and parasitic disease in the human population were analyzed in the main city of the Province of Salta using Geographic Information Systems, and the results suggested a potential influence of Arenales River. To establish the critical points for systematic monitoring, the river section that crosses the city was assessed and eleven locations (five on the river and six on discharges) were selected along the river. Physicochemical (temperature, pH, dissolved oxygen, conductivity, salinity, and turbidity, using a multiparametric probe) and microbiological variables including bacteria (total and thermotolerant coliforms, E. coli, and Enterococcus, by colony forming units count), parasites (by microscopy), and viruses (adenovirus [AdV], enterovirus [EV], and norovirus [NoV] by real-time PCR) were analyzed monthly for thirteen months. As the amount of viruses and parasites in environmental samples is usually low we used ultrafiltration to concentrate pathogens from 20 L of water to 50-70 mL. All samples were spiked with a known amount of the bacteriophage PP7 as internal control of the process to evaluate the filtration recovery, to calculate the sample limit of detection, and to assess enzymatic inhibition during PCR.   Multivariate statistical techniques were used to evaluate correlations between physicochemical variables, microbial indicators and the pathogens detected, and to design a rational monitoring scheme for the optimum use of limited resources.  Finally, quantitative microbial risk assessment (QMRA) was conducted using the densities of enteric viruses obtained from the river to calculate the risk of contracting an infectious disease caused by these microorganisms in water. Three scenarios were considered: 1) ingestion by bathing adults (BA), 2) ingestion by bathing children (BC), and 3) inhalation due to secondary contact (SC).