Possible drivers for the increased West Nile virus transmission in Italy in 2018

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

West Nile virus (WNV) has progressively endemized in large areas of continental Europe, and particularly in Northern Italy, in the Po River Valley. During summer season 2022, Italy experienced an unprecedented surge in incidence cases of WNV infections, including its main complications (West Nile fever (WNF) and West Nile neuroinvasive disease (WNND)). As knowledge, attitudes, and practices (KAP) of medical professionals may be instrumental in guaranteeing a prompt diagnosis and an accurate management of incident cases, we performed a cross-sectional study specifically on a sample of Italian medical professionals (1 August 2022-10 September 2022; around 8800 potential recipients). From a total of 332 questionnaires (response rate of 3.8%), 254 participating medical professionals were eventually included in the analyses. Knowledge status of participants was unsatisfying, as most of them exhibited knowledge gaps on the actual epidemiology of WNV, with similar uncertainties on the clinical features of WNF and WNND. Moreover, most of participants substantially overlooked WNV as a human pathogen when compared to SARS-CoV-2, TB, and even HIV. Interestingly, only 65.4% of respondents were either favorable or highly favorable towards a hypothetical WNV vaccine. Overall, acknowledging a higher risk perception on WNV was associated with individual factors such as reporting a seniority ≥ 10 years (adjusted odds ratio [aOR] 2.39, 95% Confidence interval [95%CI] 1.34 to 4.28), reporting a better knowledge score (aOR 2.92, 95%CI 1.60 to 5.30), having previously managed cases of WNV infections (aOR 3.65, 95%CI 1.14 to 14.20), being favorable towards a hypothetic vaccine (aOR 2.16, 95%CI 1.15 to 4.04), and perceiving WNV infections as potentially affecting daily activities (aOR 2.57, 95%CI 1.22 to 5.42). In summary, substantial knowledge gaps and the erratic risk perception collectively enlighten the importance and the urgency for appropriate information campaigns among medical professionals, and particularly among frontline personnel.

Public Perceptions on Non-Pharmaceutical Interventions for West Nile Virus Infections: A Survey from an Endemic Area in Northern Italy

During the last decade, cases of West Nile Virus (WNV) have occurred in the Emilia Romagna Region (ERR). Even though the notification rates remain relatively low, ranging from 0.06 to 1.83 cases/100,000 inhabitants, the persistent pathogen's circulation in settings characterized by favorable environmental characteristics suggests that WNV is becoming endemic to the Po River Valley. This study assesses knowledge, attitudes, and preventive practices toward WNV prevention among residents from 10 high-risk municipalities from the provinces of Parma and Reggio Emilia (total population: 82,317 inhabitants, census 2020). A web-based survey, based on the health belief model, was performed during the month of January 2021, with a convenience sampling of 469 participants from a series of closed discussion groups on social media (i.e., 2.1% of the potential responders). A total of 243 participants knew the meaning of WNV: Of them, 61.3% were aware of previous WNV infections in ERR, 76.5% acknowledged WNV infection as a severe one, but only 31.3% expressed any worry about WNV. Our results irregularly report preventive practices, either collective (e.g., draining standing water from items and the environment, 50.7%; spraying pesticides around the home, 33.0%) or individual (e.g., use of skin repellants when going outdoors, 42.6%). In a multivariate analysis, performed through binary logistic regression, participants reporting any worry towards WNV were more likely to characterize WNV as a severe disease (adjusted odds ratio [aOR] = 20.288, 95% confidence interval [CI] = 5.083-80.972). On the contrary, respondents supporting community mosquito control programs were more likely among people working with animals/livestock (aOR = 13.948, 95%CI = 2.793-69.653), and supporting tax exemptions for mosquito control programs (aOR = 4.069, 95%CI 2.098-7.893). In conclusion, our results suggest that future interventions promoting WNV prevention among residents in ERR should focus on perceptions of vulnerability to WNV, emphasizing the benefits of personal protective behaviors.

Epidemiology of West Nile Virus Infections in Humans, Italy, 2012-2020: A Summary of Available Evidences

In Italy, human cases of West Nile virus (WNV) infection have been recorded since 2008, and seasonal outbreaks have occurred almost annually. In this study, we summarize available evidences on the epidemiology of WNV and West Nile neuro-invasive disease (WNND) in humans reported between 2012 and 2020. In total, 1145 WNV infection cases were diagnosed; of them 487 (42.5%) had WNND. A significant circulation of the pathogen was suggested by studies on blood donors, with annual incidence rates ranging from 1.353 (95% confidence intervals (95% CI) 0.279-3.953) to 19.069 cases per 100,000 specimens (95% CI 13.494-26.174). The annual incidence rates of WNND increased during the study period from 0.047 cases per 100,000 (95% CI 0.031-0.068) in 2012, to 0.074 cases per 100,000 (95% CI 0.054-0.099) in 2020, peaking to 0.377 cases per 100,000 (95% CI 0.330-0.429) in 2018. There were 60 deaths. Cases of WNND were clustered in Northern Italy, particularly in the Po River Valley, during the months of August (56.7%) and September (27.5%). Higher risk for WNND was reported in subjects of male sex (risk ratio (RR) 1.545, 95% CI 1.392-1.673 compared to females), and in older age groups (RR 24.46, 95% CI 15.61-38.32 for 65-74 y.o.; RR 43.7, 95% CI 28.33-67.41 for subjects older than 75 years), while main effectors were identified in average air temperatures (incidence rate ratio (IRR) 1.3219, 95% CI 1.0053-1.7383), population density (IRR 1.0004, 95% CI 1.0001-1.0008), and occurrence of cases in the nearby provinces (IRR 1.0442, 95% CI 1.0340-1.0545). In summary, an enhanced surveillance is vital for the early detection of human cases and the prompt implementation of response measures.

Predicting WNV Circulation in Italy Using Earth Observation Data and Extreme Gradient Boosting Model

West Nile Disease (WND) is one of the most spread zoonosis in Italy and Europe caused by a vector-borne virus. Its transmission cycle is well understood, with birds acting as the primary hosts and mosquito vectors transmitting the virus to other birds, while humans and horses are occasional dead-end hosts. Identifying suitable environmental conditions across large areas containing multiple species of potential hosts and vectors can be difficult. The recent and massive availability of Earth Observation data and the continuous development of innovative Machine Learning methods can contribute to automatically identify patterns in big datasets and to make highly accurate identification of areas at risk. In this paper, we investigated the West Nile Virus (WNV) circulation in relation to Land Surface Temperature, Normalized Difference Vegetation Index and Surface Soil Moisture collected during the 160 days before the infection took place, with the aim of evaluating the predictive capacity of lagged remotely sensed variables in the identification of areas at risk for WNV circulation. WNV detection in mosquitoes, birds and horses in 2017, 2018 and 2019, has been collected from the National Information System for Animal Disease Notification. An Extreme Gradient Boosting model was trained with data from 2017 and 2018 and tested for the 2019 epidemic, predicting the spatio-temporal WNV circulation two weeks in advance with an overall accuracy of 0.84. This work lays the basis for a future early warning system that could alert public authorities when climatic and environmental conditions become favourable to the onset and spread of WNV.