Survey of hepatitis E virus in pork products and pig stools in Nakhon Pathom Province, Thailand

Background: Hepatitis E virus (HEV) is an important public health threat resulting in more than 3 million symptomatic cases and 70,000 deaths annually. HEV is classified into at least eight genotypes, and five are associated with human infection. Genotypes 1 and 2 primarily affect humans, whereas genotypes 3 and 4 circulate in both humans and swine and are considered zoonotic viruses. Previous studies in Central Thailand have reported human HEV isolates with high similarity to swine strains and high seroprevalence in pigs, suggesting the potential for pig-to-human transmission. Objectives: This study aimed to detect and analyse HEV in pork products and pig stools collected from local markets and pig farms in Nakhon Pathom Province in Central Thailand. Methods: A total of 177 pig stool and 214 pork product samples were detected for HEV by using RT-PCR amplification. Next, nucleotide sequencing and phylogenetic analysis were performed. Results: We found one sample of pork products (1/214, 0.5%), which was a pig liver sample (1/51, 2.0%), and 49 HEV-positive samples in pig stools (49/177, 27.7%). Phylogenetic analysis showed that all these HEV sequences belonged to genotype 3, with a high correlation between our samples and HEV from humans and swine was previously reported in Thailand. Conclusions: This study suggested that the consumption of poorly sanitized or uncooked animal meat or food and frequent exposure to pig stools may be risk factors for HEV infections in humans.