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Circulation and molecular epidemiology of enteroviruses in paralyzed, immunodeficient and healthy individuals in Tunisia, a country with polio free status since decades

Anissa Chouikha

This report is an overview of Enterovirus (EV) detection in Tunisian polio-suspected paralytic cases (Acute Flaccid Paralysis (AFP) cases), healthy contacts, and patients with Primary Immunodeficiencies (PID), during 11 years. A total of 2735 clinical samples were analyzed for EV isolation and type identification according to World Health Organization recommended protocols. The three Poliovirus (PV) serotypes and 28 different Non-polio Enteroviruse (NPEV) were detected. The NPEV detection rate was4,3%, 2.8%, and 12.4% in AFP cases, healthy contacts, and PID patients, respectively. The predominant species was EV-B and circulation of viruses from species EV-A was noted since 2011. All PVs detected were of Sabin origin. The PV detection rate was higher in PID patients as compared to AFP cases and contacts (6.8%, 1.5%and 1.3% respectively). PV2was not detected since 2015. Using nucleotide sequencing of the entire VP1 region, 61 strains were characterized as Sabin-like. Among them, six strains of types 1 and 3 PV were identified as pre-VDPV. Five types 2 PV, four strains belonging to type 1 PV, and two strains belonging to type 3 PV were classified as iVDPVs. The data presented provide a comprehensive picture of EVs circulating in Tunisia over the 11-years, reveal changes in their epidemiology as compared to previous studies, and highlight the need to set up a warning system to avoid unnoticed PVs.