As of June 28, 2015, this year’s first European West Nile Virus (WNV) human case of the season has been reported in Sofia, Bulgaria . According to the European Centre for Disease Control and Prevention (ECDC), WNV is known to be an “imported, tropical mosquito-borne disease” for the region, though the disease has been described to be present in Europe since 1950 [1,2]. The transmission season of WNV for Europe occurs between June to November .
About West Nile Virus (WNV)
West Nile Virus is a mosquito-borne infectious disease that is a transmitted to humans through the bite of an infected mosquito, often of the genus Culex . Mosquitoes become infected by feeding on infected birds, leading them to potentially transmit the virus to both humans and other animals . Additionally, WNV transmission has also been reported to occur through blood transfusions, organ transplants, as well as from mother to baby in pregnancy, delivery, and breastfeeding . Those most at risk of WNV infection are often individuals who work outside or participate in outdoor activities, leading to greater exposure to mosquitoes .
Approximately 80% of WNV infections are asymptomatic, with approximately 20% of infections developing into West Nile Virus Fever (WNF), a febrile illness that can include influenza-like symptoms, such as body aches, joint paints, headaches, vomiting, diarrhea, rash, fatigue, and weakness [2, 3]. For about 1% of those infected, severe symptoms can develop, such as encephalitis and meningitis . These symptoms are similar to dengue virus infection . Most affected individuals fully recover from WNV and while mortality from WNV is rare, fatalities from WNV usually occur among the elderly . There is currently no vaccine of WNV for humans, treatment of the disease often includes over-the-counter pain relievers to reduce fever and relieve symptoms in infected individuals .
Prevention of WNV is often based in mosquito abatement measures, including the use of mosquito nets, insect repellent, avoiding outdoor activity at peak mosquito feeding times, and wearing long-sleeves and trousers when outdoors . Additionally, reduction of animal-to-human WNV transmission includes the use of personal protective equipment (PPE) when working with sick animals or handling their tissues . Since transmission can also occur through blood transfusions and organ transplants, restriction of blood and organ donations, as well as laboratory testing, should be considered in WNV affected areas .
West Nile Virus in Europe
WNV outbreaks in Europe have increased in recent years, with 20 countries from the WHO European Region reporting the cases of the disease in the last decade . In 2010, a large WNV outbreak occurred in Greece, resulting in the “implementation of close surveillance” the following year and hundreds of locally-acquired WNV cases being reported, each year .