Molecular detection of hepatitis A virus in urban sewage in Rio de Janeiro, Brazil

Abstract

A one-year survey was conducted to examine hepatitis A virus (HAV) prevalence, distribution of genotypes and their relationship to bacterial indicators in raw and treated sewage samples. Fifty sewage samples (raw = 25 and treated = 25) were collected twice monthly from one sewage treatment plant in Rio de Janeiro. Virus concentration was performed by adsorption to an electronegative membrane followed by ultrafiltration. Viral RNA was detected by nested reverse transcriptase-polymerase chain reaction (RT-PCR) and real-time PCR and positive products were directly sequenced. Total and faecal coliform concentrations were also determined. By nested RT-PCR, HAV RNA was detected in 16/50 (32%) and eight (16%) of them were found in treated sewage samples. By real-time PCR, HAV RNA was detected in 46/50 (92%) samples and 24 were from treated sewage. Phylogenetic analyses classified nine isolates (56%) as subgenotype IA and seven (44%) as IB. Real-time PCR was more sensitive than nested RT-PCR; the presence of subgenotypes IA and IB was described and bacterial indicators cannot be used to predict HAV presence in sewage. These results demonstrated that HAV still remains in the environment after sewage treatment and could play an important role in maintaining the endemicity of HAV infection.