Background and Objective:
Vector-borne infectious diseases (VBDs) are a major public health concern worldwide. West Nile virus (WNV) was first reported in Europe in 1958. The Minister of Health, since 2002, has activated the National Surveillance Plan for WND. In 2022, 588 confirmed cases of infection in humans were reported in Italy, including 295 neuro-invasive forms and 37 deaths. In Sicily, 3 cases have been reported, 2 in Trapani and 1 in Catania. In October, a case of WND was confirmed in a woman in Ramacca (CT), in an area already under surveillance for previous cases in equines.

Methods:
After the human case, the veterinary prevention department of the ASP of Catania enforced clinical and entomological surveillance in stables within a 10-kilometer radius. The equids with nervous symptomatology were notified in SIMAN, and all animals in place were serum sampled for ELISA-IgM test and blood sampled with EDTA for RT-PCR. Anatomopathological examination was performed on the two deceased animals. An information campaign started involving mayors and breeders of Paternò and Ramacca municipalities.

Results:
The clinical surveillance revealed 2 outbreaks confirmed in equids, one in Ramacca (3 cases) and the other Paternò (21 cases). Laboratory findings for the deceased horse in the outbreak in the municipality of Paternò resulted in the isolation of WNV Lineage 1. On entomological surveillance, no mosquitos (Culex _pipiens_) were positive for WNV.

Conclusions:
Climate change could determine the increase of Culex _pipiens_ circulation, promoting the possible spillover of WNV, which is usually present only in 1-2% of circulating mosquitoes. Therefore, it’s not surprising, despite the presence of the virus in 24 equids and the human case, the virus could not be isolated in entomological samples. In conclusion, only a multidisciplinary, one-health approach could contain WNV spread and the risk of human transmission.