Surveillance of West Nile and Usutu virus infections in humans
Summer-autumn 2022
In Italy, the epidemiological surveillance of West Nile virus (WNV) infections in humans is regulated by the “National prevention, surveillance and response plan for arboviral diseases (PNA) 2020-2025”, approved by the State-Regions and Autonomous Provinces Conference on 15 January 2020. The document requires that human and veterinary (animal and entomological) surveillance for West Nile virus be integrated in a single plan, as veterinary surveillance is essential to estimating the risk of infection in humans. It also requires integration of WNV surveillance with monitoring activities for early detection of Usutu virus (USUV) circulation in areas where this virus was previously found, which often coincide with WNV-endemic areas. This makes sense considering the similarities between the WNV and USUV life cycles. Surveillance of imported and local human infections is carried out all year round throughout the country, and between early May and late November in Regions where endemic areas have been identified. In these areas, human surveillance should be strengthened and special emphasis should be given to the diagnosis of WNV and USUV infection in the population. Donors of blood, blood derivatives, organs, tissues and cells who test positive for WNV are also reported to the surveillance, to ensure the implementation of specific preventive measures, and so are any febrile illnesses recorded in the country.
Human surveillance is coordinated at the national level by the Istituto Superiore di Sanità and the Ministry of Health, which in turn submits the collected data to the European Commission and ECDC. The Regions independently develop normative and policy documents for epidemiological and laboratory surveillance in their respective territories, and submit their data to the ISS and the Ministry of Health. The findings of the surveillance system are presented in regular bulletins by the Department of Infectious Diseases of the Istituto Superiore di Sanità, in coordination with Office V of the Ministry of Health’s General Directorate for Preventive Healthcare and in collaboration with the Research Centre for Exotic Diseases (Centro studi malattie esotiche - CESME) of the Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise “Giuseppe Caporale” (IZS Teramo).