West Nile Virus and Usutu Virus: An Epidemiological Overview
Introduction
This technical report presents an overview of the epidemiological situation of West Nile virus (WNV) and Usutu virus (USUV), focusing on diagnostic surveillance.
Weekly updates with the latest reports on WNV cases in Europe are available every Friday during the transmission season.
West Nile Virus
Overview
WNV infection is a mosquito-borne zoonosis that is endemic in Europe, affecting countries in the southern, eastern, and western regions.
WNV infection in humans is a notifiable disease at the EU level, with cases reported by national public health authorities.
Epidemiology
WNV is an emerging pathogen with a complex ecology and epidemiology, involving multiple species of birds, mosquitoes, and mammals.
- Birds serve as the main reservoir for WNV.
- Mosquitoes become infected after feeding on infected birds.
- Humans and other animals can become infected after being bitten by infected mosquitoes.
WNV transmission typically peaks during the summer months, when mosquito populations are highest.
Usutu Virus
Overview
USUV is a mosquito-borne virus that is closely related to WNV.
USUV infection in humans is typically asymptomatic or causes mild symptoms, but severe cases have been reported.
Epidemiology
USUV is primarily transmitted by mosquitoes that feed on infected birds.
- Blackbirds and other passerines are commonly infected with USUV.
- Mosquitoes that feed on infected birds can transmit the virus to other birds and humans.
USUV transmission is influenced by factors such as bird migration patterns, mosquito populations, and environmental conditions.
Diagnostic Surveillance
Effective diagnostic surveillance is essential for monitoring the spread of WNV and USUV, and guiding public health interventions.
Diagnostic tests for WNV and USUV include serological assays (e.g., ELISA, IgM capture) and molecular assays (e.g., RT-PCR, next-generation sequencing).
Surveillance data helps identify areas with high transmission risk, allows for early detection of outbreaks, and contributes to the development of preventive measures.
Conclusion
WNV and USUV are emerging mosquito-borne viruses with the potential to cause significant public health concerns.
Understanding the epidemiology of these viruses and implementing effective diagnostic surveillance are essential for preventing and controlling their spread.
Ongoing research and collaboration among public health authorities are crucial for improving our knowledge of WNV and USUV, and for developing effective strategies to protect human and animal health.
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