The Chief Veterinary Inspectorate reports that increased mortality among wild birds, mainly from the corvid family, has been observed since mid-July. On July 24, samples were taken from four dead birds, and later, seven more samples were tested, which were collected from birds in the Ochota, Mokotów, Bielany, Praga Północ, and Praga Południe districts.
Birds Dying in Warsaw: West Nile Virus
"In five out of seven samples taken from hooded crows submitted for testing at the District Veterinary Institute - National Research Institute in Puławy on July 29, 2024, the presence of genetic material from the West Nile virus (WNV) was confirmed," DVI stated in a release. The results were confirmed by the European Reference Laboratory in Paris. Veterinary services explain that West Nile fever is a viral, zoonotic disease. There is a requirement to report and monitor this disease. "Monitoring involves observing the health and behavior of animals and paying attention to unusual mortality among equine species and birds," adds DVI.
West Nile Fever: Most Cases in Italy
Since the beginning of 2024, 72 cases of animal infection with the West Nile virus have been reported in the European Union. Most infections have occurred in Italy (33), Spain (8), Germany (8), and Austria (7). "The main vectors for transmitting the virus, including to humans, are blood-sucking insects such as midges, black flies, horseflies, mosquitoes, and rarely ticks. Mosquitoes play the main role in transmitting the virus due to their plague-like occurrence during periods of increased activity (from early summer to late autumn)," explains DVI.
Authorities clarify that for most people, around 80%, West Nile virus infection is asymptomatic. "Symptoms occur in only about 20% of infected patients, and in about 1 in 150 cases, the disease manifests as a neuroinfection involving the central nervous system. The mortality rate for this form of the infection is about 10%," the statement reads. Importantly, the virus does not transmit between humans.
How Does West Nile Fever Progress?
The typical incubation period for infection is 2 to 14 days, with an average of about 7 days. The mild form of the disease is characterized by fever, headaches, back and muscle pain, and sometimes nausea, vomiting, abdominal pain, and diarrhea. Some patients may develop a measles-like or papular rash. Acute symptoms last 3-10 days, but pain and fatigue may persist for several weeks. The neuroinvasive form of the disease presents as meningitis, encephalitis, or sometimes flaccid paralysis. Encephalitis occurs more often in older adults, while meningitis is more common in children. "In the current situation, the risk of symptomatic infections in humans in our country should be considered low," reassures the Chief Veterinary Inspectorate.
