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

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.

Chronic Wasting Disease Monitoring in Italy 2017-2019: Neuropathological Findings in Cervids.

Chronic wasting disease (CWD) is a prion disease that affects cervids; it is classified under transmissible spongiform encephalopathies (TSEs). CWD is particularly contagious, making its eradication in endemic areas very difficult and creating serious problems for cervid conservation and breeding. It has recently become an emerging public health risk to be managed by health authorities. Starting in 2017, active CWD surveillance in Italy has intensified with the monitoring of wild and farmed cervids. The present study summarizes findings from a histopathological survey of the brains from wild ruminants collected via CWD monitoring between 2017 and 2019. A total of 113 brains from 62 red deer (Cervus elaphus) and 51 roe deer (Capreolus capreolus) were submitted for analysis at the National Reference Center for Animal Encephalopathies (CEA) to determine major patterns of neuropathological lesions and correlated pathogens. Brain lesions were detected in 20 animals, 10 brain samples were unsuitable for examination, and 83 presented no lesions. Neuropathological examination revealed non-suppurative encephalitis or meningoencephalitis in most cases (15/20). This brain study revealed evidence for the absence of CWD in Italy and provided a reference spectrum of neuropathological lesions for differential diagnosis in cervids.

Epidemiological and Evolutionary Analysis of West Nile Virus Lineage 2 in Italy.

West Nile virus (WNV) is a mosquito-borne virus potentially causing serious illness in humans and other animals. Since 2004, several studies have highlighted the progressive spread of WNV Lineage 2 (L2) in Europe, with Italy being one of the countries with the highest number of cases of West Nile disease reported. In this paper, we give an overview of the epidemiological and genetic features characterising the spread and evolution of WNV L2 in Italy, leveraging data obtained from national surveillance activities between 2011 and 2021, including 46 newly assembled genomes that were analysed under both phylogeographic and phylodynamic frameworks. In addition, to better understand the seasonal patterns of the virus, we used a machine learning model predicting areas at high-risk of WNV spread. Our results show a progressive increase in WNV L2 in Italy, clarifying the dynamics of interregional circulation, with no significant introductions from other countries in recent years. Moreover, the predicting model identified the presence of suitable conditions for the 2022 earlier and wider spread of WNV in Italy, underlining the importance of using quantitative models for early warning detection of WNV outbreaks. Taken together, these findings can be used as a reference to develop new strategies to mitigate the impact of the pathogen on human and other animal health in endemic areas and new regions.

Predicting the impact of selection for scrapie resistance on PRNP genotype frequencies in goats.

The European Union has implemented breeding programmes to increase scrapie resistance in sheep. A similar approach can be applied also in goats since the K222 allele provides a level of resistance equivalent to that of ARR in sheep. The European Food Safety Authority stated that breeding for resistance could be offered as an option for Member States to control classical scrapie in goats. We assessed the impact of different breeding strategies on PRNP genotype frequencies using a mathematical model that describes in detail the evolution of K222 in two goat breeds, Chamois Coloured and Saanen. Different patterns of age structure and replacement rate were modelled as factors affecting response to selection. Breeding for scrapie resistance can be implemented in goats, even though the initial K222 frequencies in these breeds are not particularly favourable and the rate at which the resistant animals increase, both breeding and slaughtered for meat production, is slow. If the goal is not to achieve the fixation of resistance allele, it is advisable to carry out selection only until a desired frequency of K222-carriers has been attained. Nucleus selection vs. selection on the overall populations is less expensive but takes longer to reach the desired output. The programme performed on the two goat breeds serves as a model of the response the selection could have in other breeds that show different initial frequencies and population structure. In this respect, the model has a general applicability.