Between January 1 and September 8, 2026, the ISS national surveillance system recorded 265 confirmed cases of dengue, with 24 identified as autochthonous and the majority tied to travel abroad, according to public health data. Public health authorities noted that 56 percent of the travel-associated cases involved exposure in the Maldives, while no deaths have been reported from dengue during this monitoring period.
Dengue and Chikungunya Surveillance Trends
In addition to dengue, the surveillance system tracked 25 confirmed cases of chikungunya over the same timeframe, according to official figures. One of these chikungunya cases was classified as autochthonous, while 42 percent of the travel-associated infections involved exposure in the Seychelles. No deaths were linked to chikungunya, and the system also logged three travel-associated cases of the Zika virus with zero fatalities. According to research published in Pediatr. praxi by prof. RNDr. Vanda Boštíková, Ph.D., and Ing. Hana Střítecká, Ph.D., from the Ústav preventivního lékařství, Lékařská fakulta UK, Hradec Králové, arboviruses transmitted by arthropods present a growing global challenge that puts pediatric populations at particular risk. The authors noted that chikungunya and dengue are transmitted primarily by Aedes mosquitoes, such as Aedes aegypti and Aedes albopictus, while global climate change and urban migration enable these viruses to reach new European regions.
West Nile Virus Spread and Fatalities
West Nile virus (WNV) infections showed a wider distribution, with 594 confirmed human cases recorded across 79 provinces in 19 regions, up from 75 provinces in the previous bulletin, according to the ISS data. Of these WNV cases, 306 presented as neuroinvasive forms—including five imported cases originating from the Maldives, France, Belgium, Greece, and the Netherlands. The surveillance data also identified 81 asymptomatic cases among blood donors, 202 fever cases including one imported from Burkina Faso, four cases with other symptoms, and one additional asymptomatic case. Officials reported 41 deaths linked to WNV, which included one fatality from an imported case. The case fatality rate for autochthonous neuroinvasive forms stands at 13.3 percent, compared to 15.0 percent during the same period in 2025, when the ISS recorded 582 total cases and 39 deaths.
Global Expansion of Arboviruses and Historical Context
The broader expansion of vector-borne illnesses mirrors historical trends documented across the Western Hemisphere over recent decades. Research indicates that dengue incidence increased significantly between 2005 and 2015, while West Nile virus spread rapidly across the United States after its initial detection in New York City in 1999. Experts studying these trends point to environmental shifts, urban development, and international travel as drivers behind the wider geographic footprints of viruses like chikungunya, Zika, and Mayaro across tropical and temperate zones.
Did You Know?
According to research from Charles University, children often experience more severe disease and a higher risk of complications from arboviral infections compared to adults, making vector control and surveillance critical public health measures.
Frequently Asked Questions
What are the primary transmission vectors for dengue and chikungunya?
According to public health data and academic reviews, dengue and chikungunya viruses are primarily transmitted by mosquitoes of the genus Aedes, including Aedes aegypti and Aedes albopictus.
How many West Nile virus cases were recorded for 2026?
The ISS national surveillance system recorded 594 confirmed cases of West Nile virus infection in humans between January 1 and September 8, 2026, resulting in 41 deaths.
What is the case fatality rate for West Nile neuroinvasive forms?
According to ISS data, the case fatality rate calculated on reported and confirmed autochthonous neuroinvasive forms is 13.3 percent, down from 15.0 percent during the same period in 2025.
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