West Nile virus in Germany: 17 horses and 25 birds infected since mid-September. Why the season isn't over and how to protect your horse

What the FLI reported

On 27 October 2026 the Friedrich-Loeffler-Institut (FLI), Germany's federal research institute for animal health, published an update on West Nile virus. Its key finding: the virus has become markedly more active in the country since mid-September.

By 26 October the FLI's national reference laboratory had confirmed 17 infections in horses and 25 in wild and zoo birds. Case numbers rose sharply in October, even though the season had looked moderate until early September. As recently as 4 September the FLI had written that the virus was so far only moderately active this year, unlike in southern Europe.

Where the virus has been found

The cases are scattered across areas where West Nile virus is already known: Berlin, Brandenburg, Hamburg, Lower Saxony, Saxony-Anhalt, Saxony and Thuringia. These are states in the east and north of the country, where the virus first appeared a few years ago and has returned almost every summer since.

What's new in 2026 is a cluster of cases in south-west Germany, especially in the Upper Rhine valley (Oberrheinische Tiefebene) between the Black Forest and the Vosges. This area was not previously considered an affected region. The FLI considers it very likely that the virus has become permanently established in these new areas.

Germany compared with the rest of Europe

Compared with its neighbours, the situation in Germany remains moderate. The FLI notes that Italy, Greece and France have far more cases. Infections in animals and people are also noticeably higher in neighbouring Belgium and the Netherlands.

The FLI also refers to the joint assessment by the European Centre for Disease Prevention and Control (ECDC) and the European Food Safety Authority (EFSA): the West Nile virus situation in Europe in 2026 is unprecedented. The virus has spread over a larger area than in any previous season, and the numbers of human infections and animal outbreaks exceed those of previous years.

What West Nile virus is

West Nile virus is spread by mosquitoes — in Europe mainly common Culex mosquitoes, which live almost everywhere, including in towns. Its main hosts are birds: the virus multiplies in their blood, and mosquitoes become infected when they feed on it. Some bird species, such as crows, jays, birds of prey and owls, become seriously ill and die.

Horses and people are infected by mosquito bites but don't pass the virus on: there's too little of it in their blood to infect another mosquito. So a sick horse poses no danger to other horses or to the people around it. Dogs and cats can also be infected, but they very rarely become ill.

How the disease shows in horses

In most infected horses the virus causes no obvious signs. But in some it attacks the nervous system, and that's when the disease becomes dangerous. Watch out for:

• an unsteady gait, stumbling and uncertainty, especially in the hind legs;
• muscle tremors, twitching of the muscles of the face and neck;
• weakness, to the point where the horse can't get up;
• changes in behaviour — dullness, drowsiness or, on the contrary, restlessness;
• a raised temperature and going off feed;
• difficulty swallowing, teeth grinding or unusual lip movements.

Around a third of horses with the neurological form die or have to be put down. Many survivors recover fully, but some are left with lasting effects.

How it's diagnosed

West Nile virus can't be identified from the signs alone: other diseases of the nervous system can look exactly the same. So the vet takes a blood sample from the horse and sends it to a laboratory, which looks for specific antibodies that appear in the first weeks after infection and sometimes for the virus itself. Positive samples from regional laboratories are confirmed by the FLI's national reference laboratory — and it is those data that underpin the 27 October update.

In dead birds, the virus is looked for in the organs. This lets veterinary services know where the virus is circulating even before horses and people fall ill.

Why the virus is moving north

Twenty years ago, West Nile virus was still regarded as a disease of southern Europe. Now it appears regularly in Germany, the Netherlands and Belgium. The main reason is warm, long summers: in hot weather mosquitoes breed faster and the virus matures inside them more quickly. Migrating birds bring the virus up from the south every year, and if the summer is hot, it has time to become established among local birds and mosquitoes. The Upper Rhine valley is one of the warmest parts of Germany, so its appearance on the virus map doesn't surprise specialists.

Why the FLI says the season isn't over

Mosquitoes stay active as long as the weather remains warm, and in recent years autumn in Germany has increasingly been mild. The FLI states plainly that the 2026 West Nile season has not yet ended. So whenever birds or horses show neurological signs, vets must always consider infection with this virus among the possible causes.

For horse owners, that means it's too early to relax: for a few more weeks, a bite from an infected mosquito remains possible, especially along the Rhine and in the east of the country. Mosquito protection is needed until the nights are reliably cold.

Vaccinating horses

Vaccines against West Nile virus are authorised for horses in the EU and the UK. Germany's Standing Committee on Veterinary Vaccination (StIKo Vet) recommends vaccinating horses in areas where the virus is already present and those moving there or travelling to competitions. The primary course involves several injections, and protection doesn't develop straight away, so it's best to start before the mosquito season.

Your vet decides whether and how to vaccinate, taking into account where the horse lives, its age and any travel plans. West Nile virus has not become established in the UK, but if you're planning to take your horse to competitions in Germany, France or further south, it's worth discussing vaccination with your vet well in advance.

How to protect your horse from mosquitoes

Vaccination is the most important step, but simple measures also lower the risk of bites:

• stable your horse at dusk and overnight, when mosquitoes are most active;
• fit mosquito netting to stable windows and doors;
• use fly rugs and fly masks in the field;
• apply equine repellents according to the label and your vet's advice;
• get rid of standing water — old buckets, tyres and blocked gutters where larvae develop;
• change the water in troughs regularly and keep them clean.

What to do with dead birds

If you find dead crows, jays, birds of prey or owls, especially several at once, report it to the local veterinary authority. Birds are the first sentinels of the virus: their deaths show it is present in the area before horses fall ill. Never handle dead birds with bare hands.

What owners of birds, dogs and cats should know

People keeping pet or backyard birds in affected areas should keep them indoors or in aviaries with mosquito netting, especially in the evening. West Nile virus is hardly a danger to dogs and cats, but mosquito protection is useful for them too — in Europe mosquitoes also carry other diseases, such as heartworm (dirofilariasis). Your vet will choose mosquito protection for your dog; many dog products are dangerous to cats and must never be used on them without professional advice.

Is the virus dangerous to people

People catch West Nile virus only from mosquito bites. In most, the infection goes unnoticed or feels like a mild cold with a fever, but in older people and those with weakened immunity the virus can cause inflammation of the brain. So owners need mosquito protection themselves too: repellents, long clothing at dusk and netting on windows.

What happens next

The FLI will keep collecting data until the end of the season. With the first frosts, mosquitoes will stop flying and new cases will fall. But the fact that, according to the FLI, the virus has become established in the Upper Rhine valley means it should be expected there next year as well. Horse owners in south-west Germany should plan vaccination ahead, and practices should prepare for West Nile virus to become a normal part of the summer season. Anyone planning to take a horse to competitions in Italy, France or Greece next summer, where the virus is far more common, should also discuss vaccination with their vet in good time, several months before the trip.

When to call your vet

If your horse becomes unsteady, has muscle tremors, weakness, changes in behaviour or a temperature, call your vet straight away. Neurological signs also occur with other serious diseases — equine herpesvirus or rabies, for example — and only a professional can tell them apart through laboratory tests. Suspected West Nile virus in a horse must be reported in Germany, and West Nile fever is also a notifiable disease in the UK.