From January 1st to August 2nd, 2024, there have been a total of 17 cases of West Nile virus reported in Spain.

Nine people are currently hospitalised with it and there have been two deaths so far this year.

The virus is currently mainly affecting people in the province of Seville but it has been detected in other species in other parts of southern and eastern Spain, as well as the Valencia Community and Catalonia.  

Q: What is the West Nile Virus?

A: West Nile Virus is a viral infection usually spread through the bite from an infected mosquito. It typically comes from parasites found in birds which are then passed on to mosquitoes and then on to humans and horses. 

Q: What are the symptoms?

A: The virus doesn’t always cause symptoms, and in fact, in 80 percent of cases there aren’t any. But those who do get them typically experience a fever, body aches, headache, rashes, vomiting and diarrhoea.

In fact, out of 20 cases detected in 2023, five were diagnosed because they were blood donors who were unaware of being infected, according to sources from the Ministry of Health.  

They also confirmed that “For every known case of West Nile virus, there are 100 that are unknown”. These will be those who either are asymptomatic or have mild flu-like illnesses and don’t need to see a doctor.  

Q: Why is it so bad then and how can it lead to death?

A: It’s important to remember that less than one percent of those infected develop a more serious illnesses, but it can happen. These include meningitis, encephalitis, paralysis, or other neurological conditions. Out of these people who develop secondary infections around 10 percent can die from it, according to Spain’s Ministry of Health.  

Q: Who is more at risk of developing serious illnesses from it?

A: The Spanish Health Ministry have said the following people are at a greater risk – older men, organ recipients, those who consume excessive amounts of alcohol, those with diabetes, chronic kidney disease, cardiovascular disease, hypertension, cancer or immune diseases.  

Q: Do symptoms show up straight away?

A: No, as with many viruses, there is an incubation period. This can be anywhere from two up to 14 days.  

Q: Is it contagious?

A: No, the virus is not contagious between humans, it can usually only be spread from the bite of a mosquito.  

Q: Are there are any vaccines against the virus?

A: No, unfortunately there are not currently any vaccines for protection against it.   

Q: What’s behind the uptick in cases in Spain this year?

A: This summer has been a record-breaking season for mosquitoes in the Guadalquivir area after the abundant rain over the Easter period caused ideal breeding conditions. There are larvicidal treatments that should kill the parasites present in the mosquitoes, but many farmers have not been following advice and have neglected to spray it on the nearby rice fields, so the number has been rapidly allowed to spread.  

Researcher Jordi Figuerola from EBD-CSIC says that “the most important factor that explains the variation in the incidence of the Nile virus is the minimum temperature recorded during the winter”, this means that as the minimum temperatures get higher and higher with global warming, there will likely be more cases of the virus. 

Q: How can I protect myself from getting infected?

A: It’s all about stopping yourself getting bitten by mosquitoes. This includes using a good repellent, wearing long-sleeves or long trousers and skirts, especially in the evening. If you’re camping, you may also want to consider a mosquito net to sleep under. 

Q: Have there been cases present in Spain before?

A: Yes, mosquito experts have been warning about the high risk of West Nile Virus since 2011, but more recently in 2020, when there were 77 cases identified in Spain and eight deaths. In 2021, 6 cases causing meningoencephalitis were confirmed, all of them in the province of Seville. In 2022, there were reported four cases in Spain, two in areas not previously seen to have it before – Córdoba, also in Andalusia, and Tarragona in Catalonia. Last year, 2023, 20 cases were confirmed mainly in western Andalusia and Extremadura.

Q: Is it only present in Spain?

A: No, the virus can be found in Africa, Western Asia, the Middle East, Australia, Canada, Venezuela, the United States, as well as six other countries in Europe.