Abstract

Background: Emerging infections like West Nile fever (WNF), caused by the West Nile virus (WNV), are a growing global concern. WNF is primarily transmitted through mosquitoes and tick bites, with birds as the main reservoir. Although WNF is common in many regions, its recent detection in Armenia highlights its potential spread to new areas. A study in Armenia (1985-1999) examined 59,202 mosquito and 41,359 tick samples, identifying 126 strains of 10 arboviruses, including WNV and Crimean-Congo hemorrhagic fever virus. Researchers found 60 natural foci of arboviruses across 118 regions, covering 50.8% of the areas surveyed.

Methods: This review analyzes the epidemiology of WNF in Armenia, drawing on data from health authorities, local medical centers, and environmental monitoring. The study examines the clinical manifestations of the disease, including both mild and severe neuroinvasive forms, and explores the public health responses, such as mosquito control and educational campaigns. The role of climate change and the One Health approach integrating human, animal, and environmental health is also discussed in the context of WNV transmission dynamics.

Results: The first human case of WNF in Armenia was confirmed in August 2024. After nearly 35-40 years from the initial studies in the natural focus. By September, a total of 132 cases had been reported, though it's important to note that not all cases were diagnosed. Among the confirmed cases, there were four fatalities, resulting in a mortality rate of 1.85%. Most cases are mild, with symptoms like fever, headache, and body aches. A small proportion develop severe neurological symptoms, such as encephalitis or meningitis, which can be fatal. Elderly and immunocompromised individuals are at higher risk. Climate change is believed to help spread the virus by extending mosquito breeding seasons and expanding the range of infected vectors.

Conclusions: The recent WNF outbreak in Armenia highlights the growing threat of this disease, driven in part by global warming. Rising temperatures are expanding vector habitats, enabling the virus to spread to new areas like Armenia, where there was previously no established case definition for the diseases. A One Health approach, integrating human, animal, and environmental health, is crucial for managing future outbreaks. In Armenia, efforts focused on vector control, public awareness, and early detection, but without a WNV vaccine, prevention is vital. Key strategies include educating communities on reducing vector exposure, eliminating breeding sites, and strengthening surveillance.