Re-emergence of neuroinvasive West Nile virus infection in Istanbul during Summer 2024

West Nile virus (WNV) infection is mostly asymptomatic but can also cause severe meningitis and encephalitis, which can be fatal. The first human case of WNV in T & uuml;rkiye was documented in 2010. The last case was reported in the Istanbul outbreak in 2019, and no WNV cases have been reported in the last four years. In this report, the demographic features, laboratory parameters, and clinical results of 11 neuroinvasive WNV cases were presented in detail. These cases are the first reported cases from the Istanbul outbreak in 2024. The most common findings were altered mental status (100%, n = 11/11), fever (72.7%, n = 8/11), headache (63.6%, n = 7/11), vomiting (54.5%, n = 6/11), and nuchal rigidity (36.4%, n = 4/11). No rash was observed in any of the patients. All patients had positive WNV IgM, WNV IgG, and WNV micro-neutralization tests. During the follow-up, 2 (18.2%) patients were transferred to the intensive care unit, and one (9.1%) of these patients died on the 72nd day of hospitalization due to secondary bacterial infection. Considering the increasing number of cases, it should be kept in mind that WNV infections may be encountered more frequently in our country in the coming years.