Persistence of Giardia, Cryptosporidium, Rotavirus, and Adenovirus in treated sewage in São Paulo state, Brazil.

Abstract : 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.

Antimicrobial activity of two techniques for arm skin disinfection of blood donors in Brazil.

OBJECTIVE: Evaluation of the antimicrobial effect of skin disinfection techniques is essential to avoid the transmission of infectious agents during blood transfusion. The aim of this study was to examine the effectiveness of two methods of arm skin disinfection used in blood donors at a Hemotherapy Center in Brazil that represents an important centre for distributing haemocomponents to many cities in the country. METHODS: Two skin disinfection techniques in 50 blood donors were evaluated. For the first arm, 10% povidone-iodine/two-stage technique was used. On the opposite arm, 0.5% chlorhexidine digluconate alcohol solution/one-stage technique was used. The swabs were seeded on three culture media: blood agar, mannitol salt agar and Mac Conkey agar. Automated bacterial classification based on biochemical tests/specific substrates was performed. Donor characteristics were collected using the computerised system of the Hemotherapy Center. RESULTS: We found that microbial reduction was significantly higher for 10% povidone-iodine technique (98.57-98.87%) when compared with 0.5% chlorhexidine technique (94.38-95.06%). The species Leuconostoc mesenteroides and Staphylococcus hominis showed resistance to both disinfection techniques. We did not find statistically significant relationships between donor characteristics and microbial reduction. CONCLUSIONS: Arm skin disinfection with 10% povidone-iodine produced better antimicrobial activity. We must acknowledge that 10% povidone-iodine technique has the limitation of being a two-stage method. However, prevention of adverse events due to bacterial contamination and transfusion reactions should be prioritised. Production of hypoallergenic and stronger antiseptics that allowed a safe one-stage disinfection technique should be encouraged in health systems, not only in Brazil but also around the world.

Behavior of metals, pathogen parasites, and indicator bacteria in sewage effluents during biological treatment by activated sludge.

The purpose of this study was to evaluate the behavior of metals, pathogen parasites, and indicator bacteria in sewage effluents during biological treatment by activated sludge in a wastewater treatment plant in Ribeirão Preto (WTP-RP), Sao Paulo, Brazil. The evaluation was done during a period of 1 year. Results showed that metal concentrations in treated effluents decreased, reaching concentrations according to those established by national regulations. The activated sludge process at the WTP-RP promoted a partial removal of parasites considered as possible indicators according to the WHO guidelines. Reduction factors varied between 18.2% and 100% for agents such as Endolimax nana, Entamoeba coli, Entamoeba hystolitica, Giardia sp., Ancylostoma sp., Ascaris sp., Fasciola hepatica, and Strongyloides stercoralis. A removal was also observed in total and fecal coliforms quantification. The present study represents an initial evaluation of the chemical and microbiological removal capacity of the WTP-RP. The results should be of interest for the authorities responsible for the environmental health at municipal, regional, national, and international levels.