He who seeks finds: surveillance of Enteroviruses and Human Bocaviruses in Northern Italy wastewaters

BACKGROUND: Wastewaters surveillance has proven to be a valuable tool in detecting the spread of SARS-CoV-2 and other pathogens. Enterovirus (EV) and Human bocavirus (HBoV) are viruses that can infect humans, causing mild to severe pathologies transmitted also through the fecal-oral route. EVs are ssRNA viruses, grouped among four taxonomic species EV-A to D. HBoV is ssDNA virus mainly affects infants. Genus Bocavirus includes 4 genotypes: HBoV1 to 4, detected mainly in feces. EVs and HBoVs infections are often not notified, causing loss of data on the actual incidence. The aim of this study was to investigate the presence and diffusion of EVs and HBoVs in wastewaters. METHODS: 200 wastewater samples were collected during 2022, at the inlet of wastewater treatment plants in three cities of the Lombardy Region (i.e.: Brescia, Bergamo, and Cremona). EVs and HBoVs were detected by RT Real-time PCR and Real-time PCR respectively using specific primers for target region of the viral genome. Positive samples were genotyped by Sanger sequencing. Prevalence was calculated with the Blaker's method. RESULTS: Overall EV and HBoV prevalences were 20.5% (CI95% 15.5-26.2%) and 37% (CI95%.30.6-43:9%), respectively. EV was mainly detected in the mild season with a prevalence of 68.3% (CI95% 53.0-80.4%). Sequence analysis reported that EV-B species was the most prevalent in this study (9 samples). HBoVs positive samples’ prevalence was higher in cold season (71.6% CI95% 60.5-80.6%), than mild season. HBoV2 showed higher prevalence (85.6% CI95% 75.6-92.0%) than HBoV3. CONCLUSIONS: This study provided insight into the seasonal spread of EVs and HBoVs circulating and can contribute to understand the disease burden. Wastewaters surveillance provides a wide and more complete epidemiological data than the clinical one of a single person, rather providing information of a community of individuals making the data very valuable to the competent authorities. KEY MESSAGES: • Wastewaters surveillance is a useful tool for investigating the spread and circulation of viruses in population. • EVs and HBoVS are widespread in Northen Italy population.