West Nile virus detected in Croatia as three cases confirmed

ZAGREB, Croatia, 24 August 2026 – Three cases of AuWest Nile virus infection have been confirmed in Croatia, according to the Croatian Institute of Public Health, with health experts stressing that the disease is transmitted by mosquitoes and does not spread directly between people.

Alemka Markotić, director of Zagreb’s Clinic for Infectious Diseases, told Dnevnik Nova TV that one of the patients is currently on a ventilator in intensive care. Doctors are hopeful the patient will recover.

Markotić explained that around 80% of people infected with West Nile virus develop no noticeable symptoms, while about 20% experience milder illness. Only around 1% develop severe disease, which can include high fever and neurological symptoms such as severe headaches, vision problems and difficulties with movement.

The disease is not considered contagious between people, meaning quarantine is not required. The virus is transmitted primarily through mosquitoes, with birds and horses among the animals involved in its natural transmission cycle.

Older people and those with weakened immune systems are considered most at risk of developing severe illness. This includes people receiving immunosuppressive treatment and those undergoing cancer treatment.

Markotić also noted that transmission through blood transfusion is possible, but Croatia’s blood supply system routinely tests donations for West Nile virus.

West Nile virus is a seasonal infection, with July and August generally representing the period when cases reach their highest levels before declining.

Health experts say the current situation is broadly comparable with previous years. Larger outbreaks can occur periodically, linked to changes in mosquito populations and the spread of infection among mosquitoes and animals.

At present, the three confirmed cases appear to represent sporadic infections rather than a wider outbreak, Markotić said.