West Nile Virus (WNV) is one of the most widespread mosquito-borne viral diseases in the world. It can cause serious illness in humans, birds, horses, and other animals. As summer approaches, it’s crucial to be aware of this virus, understand its symptoms, learn about the available treatments, and recognize its global impact. This knowledge is especially important as cases of West Nile typically occur during mosquito season.

Symptoms

While most WNV infected individuals are asymptomatic, about 20% of infected individuals will develop mild symptoms including fever, headache, body aches, fatigue, skin rash and swallen lymph nodes. However, around 1% of infected individuals develop severe illness affecting the central nervous system, such as encephalitis (inflammation of the brain) or meningitis (inflammation of the membranes surrounding the brain and spinal cord). Severe cases can be fatal, with the case-fatality rate significantly higher in immunosuppressed individuals and those over 60 years old, reaching up to 30%.

Treatments

Currently, there are no vaccines to prevent or medicines to treat WNV. Care is supportive, focusing on relieving symptoms: pain relievers, hydration and hospitalization. At LWNVIVAT, we aim to design a safe WNV vaccine that covers WNV diversity and protects elderly individuals by promoting the generation of potent and long-lasting neutralizing humoral and T cell responses.

Global spread impact

First identified in Uganda in 1937, WNV has since spread globally, including North America, Europe, Asia, and Africa. The incidence of WNV varies annually and by region. In the United States, thousands of cases are reported annually, with prek transmission occurring in late summer and early fall. In Europe outbreaks are increasing in recent years. In 2023, 728 human cases of WNV infection were reported in Europe, of which 709 were locally acquired and 19 were travel-associated.

Climate change is facilitating the spread of WNV. Warmer spring and summer weather due to climate change creates favorable conditions for the virus and its mosquito vectors, accelerating mosquito development, extending their breeding season, and increasing their numbers.

The family of WNV

West Nile Virus (WNV) is a single-stranded RNA virus belonging to the Flaviviridae family and the Flavivirus genus. This genus also includes other notable viruses such as Zika, dengue, and yellow fever. Like most flaviviruses, WNV is an enveloped virus with icosahedral symmetry.