Presence of hepatitis A virus in water and its relationship with indicators of fecal contamination

The presence of the hepatitis A virus was studied in spring and river water samples, and heterotrophic plate count, total and fecal coliforms, fecal streptococci, and sulfite-reducing Clostridium were analyzed, in addition to physical-chemical indicators of fecal contamination ( conductivity, chemical oxygen demand, nitrate, nitrite, ammonia, phosphate and soluble proteins). The virus was concentrated by means of the aluminium hydroxide adsorption-precipitation method. Following the extraction of RNA, reverse transcriptase PCR, semi-nested PCR and hybridization were performed. No hepatitis A virus was detected in any of the spring water samples, yet 69.6% of the river water samples were positive. There were no significant differences in the mean values of the microbiological indicators when the positive and the negative river samples were compared, which confirms that there is no quantitative relationship between microbiological indicators of fecal contamination and the presence of hepatitis A virus. This was confirmed through a spatial analysis of the river water samples: the point of wastewater discharge was reflected in a high percentage of hepatitis A virus positive samples, regardless of the microbiological indicators. Among the physical-chemical indicators, only conductivity and chemical oxygen demand were significantly correlated with all microbiological indicators. Nitrate and nitrite show limited value as indicators of fecal contamination, and ammonia, phosphate and soluble proteins correlated best with heterotrophic plate count, total coliforms, fecal coliforms and fecal streptococci, which are microbiological indicators of short-term fecal pollution.