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Assessment of pathogenic protozoa in lentic and lotic compartments of a tropical reservoir impacted by cyanobacteria blooms in Brazil

Sandra Yamashiro, Diego Averaldo Guiguet Leal, Romeu Cantusio Neto, Regina Maura Bueno Franco

Universidade Estadual De Campinas, Instituto De Biologia, Departamento de Biologia Animal, Campinas, São Paulo, Brazil

Universidade Estadual De Campinas, Instituto De Biologia, Departamento de Biologia Animal, Campinas, São Paulo, Brazil

Universidade Estadual De Campinas, Instituto De Biologia, Departamento de Biologia Animal, Campinas, São Paulo, Brazil.

Sociedade de Abastecimento De Água e Saneamento – SANASA Campinas, São Paulo, Brazil

Key words: Cryptosporidium, Giardia, immunofluorescence, immunomagnetic separation, reservoir.

Abstract

BrionesReservoir2Salto Grande, a reservoir located in São Paulo, Brazil, is mainly utilized for recreational and agricultural activities and is exposed to animal and anthropogenic impact. The goals of this study were to investigate the contamination by Giardia and Cryptosporidium in four sites at this reservoir, intermittently impacted with cyanobacteria blooms and to verify the correlation among bacteriological indicators of fecal contamination, physicochemical variables and the occurrence of both protozoa. A total of 48 water samples were examined from lotic and lentic sites of the reservoir. Protozoa were searched by using the membrane filtration technique and direct immunofluorescence assay. Immunomagnetic separation was performed in cyanobacteria positive water samples. The positivity for protozoa was 16.6% in lotic sites (Mini-Pantanal and Saltinho) with major fecal contribution. Cryptosporidium oocysts were detected in one sample from Saltinho (mean concentration of 170 oocysts/L); Giardia cysts were detected in two samples of site Mini-Pantanal (mean concentration of 27.1 cysts/L) and in 5 samples of site Saltinho – mean concentration of 65.4 cysts/L. Moderate correlations were found between Giardia cysts and thermotolerant coliforms (=0.60), Giardia cysts and Escherichia coli (= 0.67). Both protozoa were not detected at lentic environments where high concentrations of cyanobacteria were observed. Cross-reactions with protozoa monoclonal antibodies and Microcystis ensured difficulty for the diagnosis. These results denote the inadequacy of utilization of these sites for recreational and agricultural purposes posing a threat to public health. The monitoring of these protozoa and its association with environmental factors help elucidate its fate and transport in aquatic environments.

Source: http://www.innspub.net/wp-content/uploads/2015/01/IJB-V6No2-p304-317.pdf

 

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