Full text
| |
| Author(s): |
Ana Paula Bortolotti Muller
Total Authors: 1
|
| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI) |
| Defense date: | 2000-02-28 |
| Examining board members: |
Vivian Helena Pellizari;
Glavur Rogerio Matte;
Petra Sanchez Sanchez
|
| Advisor: | Vivian Helena Pellizari |
| Abstract | |
The protozoan parasite Cryptosporidium has emerged as one of the most important contaminants of water, causing waterbone outbreaks of criptosporidiosis which have affected more than 427.000 individuals worldwide. At least 8 species of the genus Cryptosporidium has been associated with gastrointestinal disease in humans. Cryptosporidiosis can be life threatening to immunocompromised humans and can severely debilitate immunocompetent people. Cryptosporidium oocysts are environmentally robust and can survive in aquatic environments for months. Oocysts are resistant to standard chlorination disinfection used for drinking water treatment. The aims of this study were to determine the occurrence and the levels of Cryptosporidium in raw water samples and in drinking water (after flocculation, coagulation, sedimentation, filtration and disinfection) collected in two potable water treatment plants of the city of São Paulo. The relationship between parameters of water quality and the occurrence of Cryptosporidium were also analysed. Samples were collected at monthly intervals for a year. The samples were concentrated by flocculation (VESEY et alii, 1993a) and by membrane filtration (ALDOM & CHAGLA, 1994). The oocysts were identified by direct immunofluorescence assay and the presence was confirmed by phase contrast microscopy. The levels of coliforms and E.coli in the water samples were determined by the multiple tube technique using chromogenic and fluorogenic substrate (Colilert 18, Iddex). From a total of 24 samples of the each type of water investigated (12 oh the each potable water treatment plant), oocysts were detected in 75% of raw water and in 12,5% of drinking water samples, when concentrated by flocculation and in 73,91% of raw water samples and in 33,33% of drinking water samples when concentrated by membrane filtration. Cryptosporidium oocysts levels in the samples investigated was not significantly associated with microbiological indicators and water quality parameters (p > 0,05). The results suggested that the conventional treatment of water is ineffective in removing the oocysts, highlighting the necessity of establishing water catchment management programs which effectively ensure low levels of Cryptosporidium in raw water supplied to the treatment plants. (AU) | |