Molecular Evidences of Enteric Virus Contamination in Bangladeshi Foods

Enteric viruses, particularly rotavirus A (RV), norovirus GII (NV), and enteroviruses (EV), pose significant health challenges in Bangladesh, yet data on viral contamination of foods in Bangladesh remain scarce. This study investigated the presence of these fecal-oral transmitted viruses in street-vended ready-to-eat (RTE) foods and related matrices collected from high-risk locations in Dhaka using a simple, cost-effective detection approach. Four viral RNA extraction methods, TRIzol-based, PEG + NaCl precipitation, Nanotrap with Microbiome A, and direct extraction, were compared and viral RNA was detected by conventional nested RT-PCR. Bacterial indicators, including total viable counts (TVC), total coliform counts (TCC), and fecal coliform counts (FCC), were also quantified to examine their association with viral contamination. The direct washing method showed the best overall performance, combining simplicity with detection limits of approximately 3,000 and 6,800 copies/g for RV and NV, respectively. Among 205 samples, RV was detected in 6 (2.9%), with sequencing confirming two G3 genotype strains. Targeted NV and EV amplicons were detected in 7 (3.4%) and 18 (8.8%) samples, respectively. Of the 117 RTE foods, 50.4% were unsatisfactory for all three bacterial indicators, whereas only 7.7% met satisfactory criteria. No significant association was observed between bacterial indicator levels and viral detection. This study provides the first molecular evidence of enteric viral contamination in street-vended foods and related matrices in Bangladesh, providing a baseline data on foodborne viral risks and emphasizing the need for virus-specific surveillance rather than reliance on bacterial indicators alone.