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:  The persistence of Giardia, Cryptosporidium, Rotavirus, and Adenovirus in samples of raw and treated sewage collected monthly in 2010 at the Biological Wastewater Treatment Plant of Ribeirão Preto, SP, Brazil, was analyzed. The USEPA Method 1623 was used to detect and quantify Giardia and Cryptosporidium. An enzyme immunoassay was carried out to test Rotavirus and Adenovirus antigen optical density (Rotascreen® and Adenoscreen®). The results show a significant decrease in the concentrations of Giardia, Rotavirus and Adenovirus (P < 0.05) and a trend of decreasing Cryptosporidium densities, without statistical significance. Giardia concentrations ranged from 120 to 2,200 cysts/L in raw sewage and from 0.45 to 3.5 cysts/L in treated sewage. Cryptosporidium concentration ranged from undetectable to 28.9 oocysts/L in raw sewage and undetectable to 1.05 oocysts/L in treated sewage. Rotavirus presented absorbance values that ranged from 1.17 ± 0.81 in raw sewage to 0.46 ± 0.32 in treated sewage. Adenovirus, in turn, presented absorbance values of 0.64 ± 0.20 in raw sewage and of 0.45 ± 0.04 in treated sewage. There was no significant seasonal tendency observed in the distribution of protozoa (oo)cysts and in the viral antigen density in the monthly sewage samples during 2010 (P > 0.05). Even though these pathogenic agents decreased after treatment, the remaining loads observed in treated sewage can reach the watercourses receiving it. Giardia, Cryptosporidium, Rotavirus, and Adenovirus are pathogens with very low infectious doses, representing a public health risk especially for vulnerable groups, such as children living near these watercourses and homeless people using this water for various purposes. Studies addressing the environmental persistence of opportunistic pathogens in watercourses are hugely important in the public health sphere, especially in developing countries, where economic, social, cultural, and environmental factors still persist that are favorable to population's exposure to diarrhea-causing agents.

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Brazilian regulations for nonpotable reuse are being established using World Health Organization guidelines, however, they should be developed based on local monitoring studies. This study intended to analyze enteroviruses, protozoa and viable Ascaris sp. eggs in raw (24) and treated (24) effluents from four Wastewater Treatment Plants of São Paulo State, Brazil. The protozoa were detected with the US Environmental Protection Agency (USEPA) Method 1623 in the treated effluents and by centrifugation/Immunomagnetic Separation in the raw influent samples. Viable Ascaris sp. eggs were analyzed according to a modified USEPA method. Enteroviruses were quantified by using human rhabdomyosarcoma cells after adequate concentration procedures. All wastewater influents were positive for Giardia sp. whereas Cryptosporidium sp. was detected in 58.3% of the samples. Giardia sp. and Cryptosporidium sp. were present in 79.2 and 25.0% respectively, of the treated wastewater samples. Viable Ascaris sp. eggs were detected in 50.0 and 12.5% of influent and treated wastewater samples. Enteroviruses were isolated in the 24 raw influent samples and in 46% of the treated samples. Taking into account the densities of Giardia sp. in some treated wastewaters intended to be used as reclaimed water, Quantitative Microbial Risk Assessment studies should be conducted to establish pathogen quantitative criteria for a future Brazilian regulation for water reuse.

Cryptosporidium and Giardia are associated with cases of water and foodborne outbreaks in the world. This study included 50 samples of surface raw water collected from two watersheds in the state of São Paulo, Brazil. The isolation of (oo)cysts was performed in accordance with the U.S. Environmental Protection Agency's methods 1623 and genotypic characterization and quantification were carried out by Nested PCR and qPCR assays based on 18S rRNA and gdh genes, respectively. U.S. EPA 1623 method showed the presence of (oo)cysts in 40% ([Formula: see text] = 0.10 oocysts/L) and 100% ([Formula: see text] = 7.6 cysts/L) of samples from São Lourenço River, respectively, and 24% ([Formula: see text] = 0.8 oocysts/L) and 60% ([Formula: see text] = 1.64 cysts/L) of Guarapiranga Reservoir, respectively. The qPCR assay detected C. hominis/parvum in 52% (0.06 to 1.85 oocysts/L) of São Lourenço River and 64% (0.09 to 1.4 oocysts/L) of Guarapiranga Reservoir samples. Presence/absence test for Giardia intestinalis was positive in 92% of São Lourenço River and 8% of Guarapiranga Reservoir samples. The assemblage A was detected in 16% (0.58 to 2.67 cysts/L) in São Lourenço River and no positive samples were obtained for assemblage B in both water bodies. The characterization of anthroponotic species C. parvum/hominis, G. intestinalis, and assemblage A was valuable in the investigation of possible sources of contamination in the watersheds studied confirming the need of expanding environmental monitoring measures for protection of these water sources in our country.