Ukraine is grappling with a severe outbreak of West Nile virus (WNV), with health officials raising alarms as the death toll rises. Since July, the country has recorded 88 cases, resulting in 11 fatalities, according to health authorities.
In an interview with the television network BBC, Ihor Kuzin, Ukraine’s deputy minister of health and chief sanitary doctor, warned that the situation remains critical and the threat is expected to persist.
WNV is common in regions such as Africa, the Middle East, North America, and West Asia. It typically spikes between the summer and autumn months of June and September, according to the World Health Organization (WHO).
The virus is transmitted to humans through the bite of an infected mosquito, which usually contracts the virus from migratory birds or horses. Symptoms in humans can include fever, headache, vomiting, diarrhoea, rashes, and muscle aches, according to the United States Centers for Disease Control and Prevention (CDC).
While many cases go undetected, 20 per cent of infected individuals experience symptoms and one in 150 cases can develop into a severe neuroinvasive disease, which can be fatal. Currently, there is no specific treatment or vaccine for WNV.
The WHO has noted a rise in human cases and outbreaks across Europe in recent years, with several countries reporting cases for the first time.
The European Centre for Disease Prevention and Control (ECDC) has recorded 186 cases of WNV in Europe between January and October 9, 2024. Areas such as Caserta in Italy, Segeberg and Dithmarschen in Germany, Kýpros in Cyprus, and Burgas in Bulgaria are among the regions experiencing their first cases in 2024.
So far, 19 countries, including Albania, Austria, Bulgaria, Croatia, Cyprus, Czechia, France, Germany, Greece, Hungary, Italy, North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain and Türkiye and Kosovo have reported outbreaks.
The virus was first identified in Uganda’s West Nile region in 1937. Research suggests that migratory birds are the primary carriers, spreading the virus to new regions. A study from 2000 linked outbreaks in temperate areas to the seasonal arrival of migratory birds and mosquitoes.
These infections predominantly occur in wetlands with large populations of migratory birds, which come into contact with ornithophilic mosquitoes. “The principal vectors from which the virus has been isolated are mainly ornithophilic mosquitoes (Culex univittatus in the Middle East [West Asia] and C pipiens in Europe),” it stated.
Antibodies to these viruses have been detected in many migratory bird species from Eurasia, and the same birds have transported the virus to the Western Hemisphere.
The virus reached the US in 1999, causing the death of seven people in New York. Subsequent research published in 2016 in the journal Pubmed Medical highlighted recurrent outbreaks in Europe and North Africa since 1996.
Major human outbreaks occurred in Russia’s Southeastern and Eastern Europe regions, as well as the Czech Republic, Hungary, Romania, Turkey, Greece, Italy, France, Spain, and Portugal.
Annual outbreaks in these regions since 2010 point to an endemic transmission cycle and a growing public health concern.
Warmer and wetter weather conditions, exacerbated by climate change, are increasing mosquito breeding grounds, according to the WHO. As ambient temperatures rises and warmer days lengthen, mosquitoes' survival rates, development and feeding frequency are likely to increase, the research stated.
With Europe already warming faster than the global average, and predictions of temperature increases ranging from 1 to 5.5 degrees Celsius by the end of the century, the spread of WNV is expected to impact larger regions of Europe and its neighbours.