Emerging Non-Polio Enteroviruses recognized in the framework of the Acute Flaccid Paralyses (AFP) surveillance system in Northern Italy, 2016-2018

BACKGROUND: Acute Flaccid Paralyses Surveillance (AFPS) monitors the emergence of polioviruses and can track non-polio enteroviruses (NPEVs). We report the findings of AFPS activities in Lombardy region (Northern Italy) from 2016 to 2018.METHODS: Faecal and respiratory samples were collected from children <15 years who met the WHO definition of AFP case and analysed by virus isolation in cell cultures (RD/L20B) and by a one-step real-time RT-PCR assay specific for the 5'-noncoding-region of NPEV. NPEV-positive specimens were further analysed by sequencing of a fragment of the VP1 gene.RESULTS: 36 AFP cases (89 stool and 32 respiratory samples) were reported with an incidence of 1.1/100'000, 0.9/100'000, 0.6/100'000 children <15 years in 2016, 2017, 2018, respectively. Poliovirus was not identified, whereas NPEVs were detected in 19.4% (7/36) of AFP cases. The presence of one Echovirus-25 (2016), two EV- and D68 (2016 and 2018), one EV-A71 (2016) and one Echovirus-30 (2016) sharing high nucleotide identity with NPEVs detected in Europe was identified.CONCLUSION: The absence of polio was confirmed. The unpredicted detection of emerging EV-D68, EV-A71, E-30 sharing high sequence nucleotide similarity with viruses involved in the latest outbreaks, provided valuable and up-to-date information, emphasising the importance of monitoring NPEVs through AFPS.