WNV circulation has been proven in 50 provinces across 16 Italian regions, including Piedmont, Lombardy, Veneto, and Sicily. In parallel, the national surveillance system recorded three cases of Usutu virus, all located in Lombardy. The data underscores the widespread geographic distribution of the virus, which is transmitted by mosquitoes and can cause severe neurological complications in susceptible individuals.
Concurrently, Italy has experienced a notable resurgence of Chikungunya, with 385 indigenous cases reported between January 1 and November 18, 2025. The national total for Chikungunya stands at 453 cases, including 68 travel-related infections. The median age of affected individuals is 59 years, with 50% of cases occurring in men. No deaths have been associated with Chikungunya infections. The majority of indigenous cases stem from seven episodes of local transmission identified in four regions: Emilia-Romagna, Veneto, Tuscany, and Basilicata.
The largest outbreak, centered in a municipality within the Province of Modena in Emilia-Romagna, accounts for 318 confirmed symptomatic cases. A second outbreak in the Province of Veneto, involving multiple municipalities, has recorded 61 confirmed cases. A third, smaller outbreak in the Province of Bologna with two cases is considered concluded. Four additional sporadic events have been identified, three of which are closed, while epidemiological investigations and vector control activities remain ongoing in the affected areas.
Dengue fever also demonstrated local transmission potential, with four indigenous cases reported out of 182 total confirmed cases from January 1 to October 21, 2025. Two separate local transmission events occurred in Emilia-Romagna and Veneto, both now concluded. The median age for dengue patients was 38.5 years, with 55% being male. No deaths were reported in association with dengue. Other arboviruses monitored include Zika virus, with three travel-related cases, and Tick-Borne Encephalitis (TBE), which recorded 48 cases (45 indigenous) and one death. Toscana virus infections numbered 105, with one death recorded.
These figures mark a significant shift from the historical pattern in Italy, where Chikungunya, Dengue, and Zika were primarily recorded as imported cases. The first outbreak of Chikungunya in a temperate climate country was identified in northern Italy in 2007. The subsequent re-emergence and sustained local transmission cycles indicate that vector-borne viruses are becoming established endemic threats in European environments. Arboviruses, transmitted by mosquitoes, ticks, and sandflies, are zoonoses affecting both humans and animals. Over 100 viruses are classified as arboviruses, and their expanding range complicates differential diagnosis for both travel-related and domestic febrile illnesses.
Public health authorities emphasize that the expansion of vector habitats, influenced by climatic changes, necessitates heightened surveillance. The co-circulation of multiple arboviruses in the same geographic areas increases the risk of concurrent infections and diagnostic challenges. Continued monitoring of blood donors and active vector control remain central to mitigating the public health impact of these emerging endemic threats in Italy.
