Molecular Detection of Hepatitis A Virus in Urban Sewage in Isfahan, Iran

Hepatitis A virus (HAV) enters sewage through the stool of infected patients and contaminates freshwater and seawater. The aim of present study was quantitative molecular detection of HAV in raw and treated urban sewage samples from Isfahan, center of Iran.

Material and Sewage samples were collected from six urban treatment plants in cold and warm weather, between December 2016 and Jun 2017. Physicochemical indicators were measured immediately after sampling. Viral particles were isolated and concentrated by modified adsorption-elution method using Al3+coated filters. Quantitative PCR was done for amplification of a fragment in the highly conserved 5′ noncoding region of the HAV genome.

Although the values of the indicators were lower in 67-83% of sewage samples in warm weather, no significant difference was detected between the physicochemical indicators of sewage samples. HAV was detected in three raw sewage samples collected in cold weather (copy number of 32590, 28400 and 14200 per µl) and in one treated sewage sample (copy number of 6500 per µl) collected in cold weather. Positive HAV sewage samples had been treated by activated sludge and aerated lagoon.

We detected high frequency of HAV in raw urban sewage samples from Isfahan, Iran. This highlights the importance of paying extra attention to irrigation of farms with raw sewage. Based on the results of this study and previous studies, it can be concluded that the activated sludge system may be more effective for elimination of enteric viruses, such as HAV.