Rapid increase in neuroinvasive West Nile virus infections in humans, Italy, July 2022

Abstract

As in 2018, when a large West Nile virus (WNV) epidemic occurred, the 2022 vector season in Italy was marked by an early onset of WNV circulation in mosquitoes and birds. Human infections were limited until early July, when we observed a rapid increase in the number of cases. We describe the epidemiology of human infections and animal and vector surveillance for WNV and compare the more consolidated data of June and July 2022 with the same period in 2018.

West Nile Virus Infection: A Cross-Sectional Study on Italian Medical Professionals during Summer Season 2022

“…Still, as our study was performed during an unprecedented outbreak of WNV infections in the whole of the country [19,[40][41][42], the present study may contribute to our understanding of baseline knowledge, attitudes and practices of medical professionals involved in the early identification and monitoring of this potentially serious infectious disease. As the large majority of WNV infections cases may occur without suggestive clinical signs and symptoms [17,23,[94][95][96], assessing the actual understanding of WNV among healthcare providers may contribute to a better appreciation of the effective burden of disease in the general population [8,17,18,97].…”

“…Risk perception and knowledge status were not only correlated (Spearman's rho = 0.156; p value = 0.013), but scoring a better knowledge status was identified as a positive effector for reporting higher risk perception (aOR 2.92, 95%CI 1.60 to 5.30). Still, even though the present study was performed during an unprecedent reporting season for WNV [41,42], participants were characterized by a relatively low risk perception (RPS 37.7% ± 17.5). In fact, WNV infections were generally considered as a lesser threat for public health than more "conventional" pathogens such as Mycobacterium tuberculosis and HIV, as well as SARS-CoV-2.…”

“…Even though the potential burden of WNV infections was perceived akin to that associated with an important pathogen such as seasonal influenza, the latter is often underscored as a relatively indolent disorder, not only in the general population but also among Italian medical professionals [50][51][52], and the correspondent vaccine has been in turn often discredited by media [53][54][55][56][57][58][59]. A possible explanation may be found in the coverage of conventional and new media on the ongoing WNV outbreak in Northern Italy [40][41][42]. While an accurate measurement of the qualitative and quantitative coverage of a specific topic by conventional media remains particularly difficult to achieve, with obvious consequences on the eventual modeling of knowledge, beliefs, and perceptions of targeted study group, a proxy for new media has been developed and provided by Google TM through Google Trends™ and the calculation of relative search volumes (RSV).…”

“…This design was motivated by the lack of similar studies on medical professionals, and particularly from endemic areas of continental Europe. Even though WNV has progressively become an endemic pathogen to Northern Italy, and particularly to the Po River Valley [27,28,30,42,[70][71][72][73], the actual understanding of WNV infections among Italian healthcare providers has been only scarcely inquired. Shortly before the inception of SARS-CoV-2 pandemic, a KAP study on 174 Italian occupational physicians [48] identified a relatively satisfying understanding of WNV infections and their preventive measures, still stressing the extensive underestimation of their actual occurrence in the general population and their severity as well.…”

“…Some explanations may be found in the characteristics of targeted professionals [74,75], as the individual expertise of occupational physicians-medical professionals primarily involved in health surveillance and preventive interventions in the workplaces-can be hardly compared to that of other medical professionals [47,48,[75][76][77]. Another substantial factor could be identified in the decrease in notification rates for WNV infections between 2020 and 2021 [19,38,39], which was then followed by the unprecedented reporting season 2022, which was also characterized by a particularly high case fatality ratio [40][41][42]. In other words, after two reporting seasons with a low or even a very low circulation of the pathogen, participants may have been led to the perception of WNV as a relatively uncommon disorder, while the high lethality reported in 2022 could have inflated the perceived severity of WNV infections.…”