Rotavírus em águas superficiais da bacia hidrográfica do córrego São Pedro, Juiz de Fora, MG

Abstract

The continuous discharge of domestic sewage “in natura” in spring waters is regarded as a major risk to public health, since the human feces can contain enteric pathogens that contaminate water and are spread by through it. It is important to know the quality of water used by the population, however the parameters analyzed for human exposure to natural waters include bacteriological indicators only, disregarding the presence of viruses. Thus, this study investigated the contamination of spring waters of the drainage basin of the São Pedro (BHCSP) by group A rotavirus (RV-A), as well as checking the efficiency of the detection techniques and the presence of correlation between these viruses and microbiological parameters and physicochemical water quality. From July 2011 to May 2012, surface waters samples were taken in eight georeferenced points (four in non-urbanized area and four in urbanized area), in six campaigns (three in the dry season and the three in wet season), totaling 48 samples. Physicochemical and microbiological parameters of water quality were determined in all collections, in the samples of waters of all points. The samples were concentrated using an adsorption-elution method with a negatively charged membrane and the concentrates were subjected to qualitative and quantitative PCR. RV-A were detected in 62,5% (30/48) of the studied samples with the viral load ranging from 4,74X102 - 6,36X104 genomes copies/L. The real time PCR was more sensitive in detecting virus (p = 0,001). Statistical analyzes showed that the presence of RV-A (p < 0,001) and viral load (p < 0,001) were influenced by the collection area, indicating a greater likelihood of finding positive samples with higher load in urbanized area of the basin, where there is discharge of raw sewage. There were no associations between detection (p = 0,371) and viral load (p = 0,297) with the season of collection. The presence of RV-A was observed in 50.0% (11/22) of samples considered within the limit established by thermotolerant coliforms in freshwater class 1 and 2 demonstrate, therefore, that this pattern does not guarantee the absence of human enteric viruses. Measured physicochemical parameters displayed significant associations between the presence RVA and turbidity (p = 0.005), content of ammonia nitrogen (p <0.001) and content of phosphorus (p <0.001). It was also observed a weak positive correlation between viral load the RV-A and the salinity parameters (r = 0.024 p = 0.325) and water temperature (p = 0.027, r = 0.320). These data indicate that the microbiological standard officially used to determine the water quality does not ensure the absence of viral pathogens, being necessary to establish an environment surveillance of enteric viruses in surface waters, in order to increase the safety of using this aquatic matrices for many purposes.