- Sheep and Cattle Experience Wave of Bluetongue Virus Impact
Blue Tongue Disease, which poses a threat to sheep and cattle, is spreading rapidly in Germany. The number of cases is currently skyrocketing, as reported by the Friedrich-Loeffler-Institute (FLI) on the island of Riems. The reason for this is the high number and extreme activity of disease-carrying midges for several weeks.
Over a period of just ten months, the pathogen has spread across Germany. After Saxony was added on Friday, there have been no reported cases in Berlin yet, as per the FLI's announcement.
What type of pathogen is it?
It is a virus, more specifically the Blue Tongue Virus, or BTV for short. Sheep, cattle, South American camelids, goats, and wild ruminants are particularly susceptible to this virus, which exists in over 20 different variants, known as serotypes. Currently, the type BTV-3 is prevalent in Germany and other European countries.
How do sheep and cattle become infected?
Most BTV viruses are transmitted by blood-sucking midges from the Culicoides group, which are part of the biting midge family. They breed mainly in warm weather with high humidity.
According to a "Science" journal article, midges can fly several kilometers in a few days - even hundreds of kilometers with a tailwind. The transportation of sick animals can also contribute to the spread of the virus. Following a bite from an infected midge, the virus multiplies in certain lymph nodes. Infected animals are typically immune for life. Once infected with the current variant, animals will not get sick again - but they can with other serotypes.
How harmful is the virus to humans?
It is completely harmless to humans, as confirmed by the Friedrich-Loeffler-Institute. The pathogen is not transmissible to humans. Meat and dairy products from vulnerable animals can be consumed without concern.
How do affected animals fare?
Blue Tongue Disease is extremely painful and can be fatal, depending on the serotype. Sheep often suffer severe mouth pain and lameness, as reported by the FLI. The characteristic discoloration of the tongue is relatively rare. In cattle, the disease has a milder course.
According to data from the Netherlands, which has been affected for a longer period, on average, a quarter of sheep in affected holdings die from the current variant BTV-3/NET2023 - significantly more than with other variants. In some farms, even more than 70 percent of the sick animals have died. The mortality rate is also higher in cattle, and milk production can significantly decrease in dairy cows.
What is the current situation?
In recent days, cases have been reported from more and more federal states. While the FLI recorded 13 affected livestock operations nationwide in June, there were already over 1,200 in July. And by August 23 alone, more than 4,800 affected operations had been reported.
The FLI expects more cases and more affected operations throughout the year. And: "We will definitely be dealing with BTV-3 in the coming year as well."
There are approximately 10.6 million cattle in Germany (as of May), with around 3.7 million being dairy cows. Bavaria, Baden-Württemberg, Lower Saxony, North Rhine-Westphalia, and Schleswig-Holstein account for over 75 percent of the cattle.
The spread of Blue Tongue Disease serotype 3 is progressing in a similar manner to that of serotype 8 in 2007, according to the FLI. Initially moderate, the number of new cases typically increases sharply in the second half of the year and then decreases again towards the end of the year, depending on the presence and activity of the transmitting midges.
Where does the BTV-3/NET2023 variant originate from?
It is suspected to have originated in southern Africa, although this has not yet been confirmed or refuted by the FLI. The significant differences from all previously known BTV-3 outbreaks in Europe suggest a distant origin.
The federal institute considers global trade to be the likely means of introduction. Not necessarily with sheep or cattle: infected midges could also have been brought in with materials.
The variant was first detected in the Netherlands in September 2023 and spread rapidly. The first infection in Germany was confirmed in October 2023, in a sheep farm in North Rhine-Westphalia.
Experts generally agree that climate change facilitates outbreaks of the disease by making it easier for midges to overwinter and subsequently spread more quickly. Higher temperatures also promote the reproduction of the pathogen in midges.
What does the epidemic mean for farmers?
Due to the outbreaks, Germany's status as "free from Blue Tongue Disease" has been suspended. Animals from affected areas can only be moved to BTV-free areas after testing and treatment with insecticides, which could significantly hinder trade.
"Since all federal states are now affected, trade within Germany should be possible again without special requirements," said the farmers' association. However, trade with BTV-free regions in the EU is strongly restricted or subject to certain conditions.
Farmers also face losses due to reduced milk production and dead animals. During the BTV-8 epidemic in 2007, Germany's animal disease compensation funds paid out for 33,233 dead sheep and 10,240 dead cattle, according to the FLI.
Can anything be done to combat this?
An emergency ordinance has made it possible to use three BTV-3 vaccines. These can reduce symptoms and viral replication in animals, according to the FLI. However, they do not provide full protection, and vaccinated animals can still become infected.
According to the Future of Life Institute (FLI), vaccinations are the sole defense mechanism for animals. However, voluntary vaccination, which is commonly financed by the animal owners, has a lower acceptance rate compared to mandatory vaccination, which is usually funded by the animal disease fund.
As per the farmers' association, "vaccines are extensively utilized." Regrettably, they weren't accessible in a timely manner for the initially affected areas. The success of vaccinations in safeguarding the animal population will significantly impact the duration of the epidemic.
The spread of Blue Tongue Disease in Germany is primarily due to the high activity of disease-carrying midges, specifically from the Culicoides group, which thrive in warm weather with high humidity. According to the text, 'Agriculture' in Germany, particularly cattle and sheep farming, is currently impacted by the rapid spread of the BTV-3 serotype of the Blue Tongue Virus.
