Ten Year Survey of Salmonella and Enterovirus in Raw and Treated Waters in the Great São Paulo Area, Brazil

The monitoring program for Enterovirus and Salmonella in raw and treated waters, from nine water treatment plants of Great São Paulo, Brazil, has been developed by CETESB- The São Paulo State Environmental Protection Agency under a contract with SABESP - Water Industry and Sewage Works Company, since 1976. For Salmonella analysis a total of 904 samples of raw water and 997 of treated water were analysed during these last 10 years. A percentage of 30.6 of 904 raw water samples revealed the presence of Salmonella. These pathogenic bacteria were absent in treated water. For Enterovirus, 383 samples of raw water were analysed, out of these 14.9% revealed the presence of virus. From a total of 366 viruses isolated 195 (53.3%) were Poliovirus, 79 (21.6%) were Echovirus, 30 (8.2%) were Coxsackievirus and 62 (16.9%) isolates were untyped. As far as treated water is concerned for the 10 year study, only 3 out of 975 samples were positive for viruses (Poliovirus type 2, Coxsackie A16, and one isolate untyped). Coliforms and Salmonella were not detected in these 3 samples. Residual chlorine was present. In the sample where Poliovirus type 2 was present, free residual chlorine was 1.5 mg/L and pH 9.2. This survey demonstrated that the conventional procedures for water treatment used by SABESP were in general efficient for Enterovirus and Salmonella removal.