In just a few months, lumpy skin disease (LSD) has led to a proliferation of outbreaks and forceful sanitary mitigation measures, including the systematic culling of infected herds in France. What is this disease? How is it transmitted? Why is it so difficult to contain? A group of experts, veterinarians from the Faculty of Veterinary Medicine at the University of Liège, put the facts into context.
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irst detected in France on 29 June 2025, LSD is a viral disease of cattle – posing no risk to humans – with serious consequences for livestock farms (fever, skin nodules, reduced production) and no cure. To curb its spread, the French government has implemented a health strategy based in particular on the systematic culling of affected herds (even if only one animal is sick), in addition to movement restrictions and accelerated vaccination. France has recorded 114 outbreaks since 29 June and thousands of animals have been culled, triggering strong anger and protests from farmers who denounce the measure as "disproportionate" and demand for more vaccines, with blockades and growing tension (including towards veterinarians).
France is not alone in being affected. Outbreaks were detected earlier in Italy in June 2025 (Sardinia and then Lombardy), and Spain confirmed its first outbreak in Catalonia in early October 2025 and has recorded several since then.
Laurent Gillet and Claude Seagerman, experts in veterinary public health at the Department of Infectious Diseases of the Faculty of Veterinary Medicine at ULiège, offer some insights to better understand this disease, its symptoms, how it spreads and the health measures put in place to eradicate it.
What is lumpy skin disease (LSD)?
LSD (also known as Dermatose Nodulaire contagieuse in French) is a disease of cattle first described in the late 1920s in Africa (Zambia). Long confined to the African continent, it gradually spread from 1989 onwards to the Middle East, Asia and then Europe in recent decades, becoming a major animal health concern. LSD is caused by a virus, the lumpy skin disease virus , which belongs to the Capripoxvirus genus. This group of viruses is closely related to the virus responsible for human smallpox, which has now been eradicated, as well as other well-known poxviruses in animals, such as sheep and goat pox. These viruses share a similar structure and biological mechanisms, even though they infect different species. The LSDV infects almost exclusively domestic cattle, with varying susceptibility depending on the breed. This virus therefore poses no significant danger to other animal species and is also harmless to humans.
How does this disease manifest itself in infected cattle?
In affected cattle, the disease manifests itself as fever, a decline in general health and, above all, the appearance of firm skin nodules, sometimes numerous, which can reach several centimetres in size and cover the entire surface of the body. These lesions can ulcerate, leave permanent scars and be accompanied by damage to the mucous membranes and lymph nodes. The economic consequences for farms are significant: a drop in milk production, weight loss, abortion, reduced fertility, depreciation of hides and sometimes mortality (1 to 5% of animals in a herd and up to 10% among the youngest). To date, there is no treatment for this disease. LSD therefore poses a serious risk to the profitability of farms and, more broadly, to the stability of the cattle sector.
What is the epidemiological situation in Europe?
Over the last decade, sporadic outbreaks of LSD have occurred in Europe. The disease first reached the Balkans in 2015-2017, leading to several outbreaks in Greece, Bulgaria and neighbouring countries (the former Yugoslav Republic of Macedonia, Serbia, Kosovo, Albania and Montenegro). This epizootic (a term similar to epidemic but for animal species) was then eradicated thanks to extensive vaccination campaigns and strict health measures, and no cases have been reported in Europe since 2017.
In 2025, the situation changed abruptly: outbreaks were confirmed in Italy (Sardinia and then Lombardy) from June onwards, marking the first modern appearance of LSD in Western Europe. Shortly afterwards, France reported its first cases in Savoie at the end of June 2025, with the disease subsequently spreading to several other departments. In October 2025, Spain reported its first outbreak in Catalonia, near the French border.
How is the disease transmitted?
LSD is mainly transmitted by mechanical vectors, i.e. insects that carry the virus from one animal to another without being infected themselves. All arthropods that bite cattle in Europe (stomoxes, horseflies, mosquitoes and ticks) can potentially play a role in transmitting the LSD virus from one bovine animal to another. When they bite an infected bovine animal, they can carry the virus on their mouthparts and then transmit it to a healthy bovine animal during a subsequent bite. This indirect transmission explains the rapid spread of the disease, especially in hot and humid weather, which is conducive to the proliferation of insects. The virus does not persist for long on the insect, which remains potentially infectious for only a few hours after biting a sick animal.
Direct transmission between cattle is possible but remains secondary. It can occur through close contact with skin lesions, secretions (saliva, nasal discharge), or infected tissues. The virus can also be present in milk, semen, or skin scabs, contributing to its persistence in the immediate environment of sick animals.
Finally, indirect transmission via contaminated equipment (needles, livestock equipment) is possible, although less common.
How can the rapid spread of the epidemic over very long distances be explained?
It is estimated that, on average, the virus spreads about 5 to 10 km per week in rural areas where livestock are scattered and vectors are abundant. However, humans play a central role in the spread of the disease. This is because every time an infected bovine animal is moved (accompanied or not by vectors such as stable flies), even if it appears healthy, it can introduce the virus into a new herd. This occurs during legal transport, such as sales or transfers between farms.
The problem is even greater with illegal or uncontrolled transport. Sick animals or animals in the incubation period can travel tens or even hundreds of kilometres, causing sudden outbreaks far from any infected areas. In this case, the spread far exceeds that of insects (in terms of the distance an insect can travel by flight).
How can LSD be controlled?
As explained above, there is no cure for LSD. In the European Union, the fight against LSD is therefore based on strict measures to protect livestock and prevent the spread of the virus.
Why is it difficult to detect animals in the incubation phase?
Early detection of infected animals is particularly challenging. This is because they can carry the virus during the incubation period without showing any clinical signs. During this phase, the virus is present in the body but in too small a quantity to be reliably detected by conventional tests, whether PCR or serology. Serological tests detect antibodies produced by the animal, but these have not yet appeared at the onset of infection. PCR tests, which look for the virus's genetic material, may fail if the viral load is very low.
In practice, this means that animals appear healthy but may already be transmitting the virus, rendering early detection ineffective and posing a very high risk to neighbouring herds, which could lead to a situation out of control.
Why is the entire European cattle population not vaccinated?
Vaccination against LSD is very effective in protecting cattle, but it is not applied to the entire European livestock population for several reasons.
Firstly, LSD is not present throughout Europe. Vaccination is mainly necessary in risk areas, close to outbreaks or in regions where vectors (biting insects) are abundant. Vaccinating all cattle, even in disease-free regions, would therefore be costly and unnecessary, with little epidemiological benefit.
Secondly, the vaccines used are live attenuated vaccines, which require rigorous management. Mass vaccination without control could complicate disease surveillance, as vaccinated animals develop antibodies similar to those of infected animals, making it difficult to distinguish between natural infection and immunization.
Finally, the logistics and cost are significant. Vaccinating millions of cattle in all European countries would require considerable resources in terms of equipment, manpower and veterinary monitoring. This vaccination would also have to be repeated periodically. In practice, and according to manufacturers' recommendations, annual vaccination is generally considered appropriate to maintain optimal protection in a herd, even though the actual duration of immunity may sometimes exceed one year.
LSD poses a major threat to the agricultural sector. Although direct mortality remains relatively low, this disease causes a sharp drop in production, economic losses related to hides and fertility, and requires heavy sanitary measures, such as the systematic culling of herds. Its spread, facilitated by insect vectors but above all by animal movements, can quickly affect large areas, endangering the stability of livestock farms and food security.
The best way to combat LSD therefore remains prevention: preventing its emergence in new regions. This requires rigorous surveillance, rapid reporting of suspected clinical cases, strict control of animal movements (biosecurity), control of insect vectors and targeted vaccination in risk areas. By limiting the introduction of the virus, it is possible to protect livestock, avoid economic losses and preserve the health of European livestock, because once the disease has taken hold, combating it becomes a long, costly and very complex process. In short, prevention is always better than cure when it comes to this highly contagious viral disease.
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