Surveillance of respiratory viruses in 2024/2025 season in the province of Treviso (Italy)

After SARS-CoV-2 pandemics national and regional surveillance of respiratory pathogens gained particular attention to control and prevent emerging and existing viral epidemics outbreaks. The genome of influenza viruses is subjected to seasonal antigenic drift and to antigenic shift over the years, which causes changing in its genome sequence and requires update of diagnostic methods. RespiVirNet is an important surveillance network which collects epidemiological data at regional and sub-regional level to provide seasonal national reports. This study aims to provide the number of positive cases of respiratory pathogens among Treviso province's hospitalized patients by following the RespiVirNet surveillance setting. Influenza A pdm09, A H3N2, A H1N1 virus, Respiratory syncytial virus A and B, Metapneumovirus, human Adenovirus, human Enterovirus, human Rhinovirus, human Coronavirus OC43 are the targeted viruses. The pathogen detection was performed in nasopharyngeal samples, bronchial aspirates and broncho alveolar lavages through the tagging oligonucleotide cleavage extension (TOCE) and multiple detection temperatures (MudT) technologies. The innovation of this method consists of a multiplex one-step real-time nested RT-PCR to detect respiratory viruses and influenza subtypes. The thesis results report about the most prevalent viruses and the positivity percentages by demonstrating their targeted population and their seasonal circulation. Human Rhinovirus positives prevailed over the other viruses, followed by human Coronavirus OC43 and Influenza pdm09 virus circulating during winter months till April, while Metapneumovirus reached its peak in spring. The data collected were compared to the ones registered by the RespiVirNet national reference to provide two different sample-populations. Data about Influenza vaccination are included in this project thanks to Treviso’s Sentinel doctors’ samples, collected at Treviso hospital and analyzed in Padua. Positive vaccinated patients for influenza virus represent a small percentage over all the vaccinated in the provincial sample-population. The epidemiological situation of Treviso province's hospitalized patients can be considered as a sample-population mirroring the national overview to monitor the trend of respiratory viruses. The data collected during this thesis work underline the importance of a surveillance plan to follow up the frail conditions, to control the possible outbreaks of new diseases, and to update the seasonal vaccine formulation.