Chikungunya virus: “Conditions for local transmission are currently favorable”

Even if China's rigor is unusual, the disease is not. China is just one stage in its current expansion. It has long been present in Europe as well – most recently in Alsace, just a few kilometers from the German border. Therefore, a travel vaccination recommendation has recently been issued. Time to take a closer look at this infectious disease.

Is the pathogen new?

Not really. The disease was first observed in Tanzania in 1952, which is where its name comes from. Chikungunya translates as "the suffering that bends people." The name describes the most noticeable and feared symptom of the disease. It can cause joint pain so severe that people writhe in agony.

The recent increase in reports about the disease is due to its increasing spread. Driven by climate change, globalization, and urbanization, the pathogen has been conquering more and more new areas since 2004. It then affects residents who lack immunity.

How is the pathogen transmitted?

The virus is transmitted by mosquitoes , primarily yellow fever mosquitoes ( Aedes aegypti) and tiger mosquitoes (Aedes albopictus). Both species bite primarily during the day. The tiger mosquito is also found in regions of southern and central Europe, including some in Germany.

How dangerous is the disease?

Many cases are likely mild and therefore go undiagnosed, making it difficult to make precise statements about the prevalence of the disease. The World Health Organization (WHO) estimates that more than half of those infected experience symptoms. In more severe cases, a sudden high fever and severe joint pain occur approximately four to eight days after the mosquito bite. At least 30 percent of those affected can expect the joint pain to last for more than three months. Studies suggest that about five percent of those infected still experience pain even after two years.

In rarer cases, complications can also occur involving the eyes, heart, and nervous system, such as inflammation of the brain or meninges. Severe cases are particularly common in newborns, the elderly, and those with pre-existing medical conditions. However, deaths are rare. There is no specific treatment for the condition; rather, therapy focuses on symptom relief, such as fever reducers and painkillers.

Where does the disease occur?

The virus is native to tropical and subtropical regions of the world. According to the WHO, transmissions have been documented in 119 countries to date. A total of more than 460,000 suspected cases of chikungunya were reported in 2024.

According to the European Centers for Disease Control and Prevention (ECDC), the disease has not yet taken hold in the EU. Nevertheless, travelers continue to bring the virus from other countries. In Italy and France, it is now more common for the tiger mosquito, which is common there, to transmit the virus from travelers to other people. Sometimes the insects infect only a very few people, but they have also triggered outbreaks with 200 or more than 300 infected individuals.

This year, a particularly high number of infections have occurred in France – and this relatively early in the year. According to Celine Gossner of the ECDC, this is due, among other things, to "significant outbreaks" in the French overseas territories of Réunion and Mayotte, meaning a particularly high number of cases have been imported. In addition, "In June, severe heat waves occurred in Western Europe and the Mediterranean region, creating favorable conditions for the tiger mosquito to multiply and the transmission of the Chikungunya virus," the head of the department for animal-borne diseases told the SZ newspaper. Warm weather not only allows mosquitoes to thrive, but also promotes the multiplication of the virus within them. At the same time, warmth shortens the time between the insect ingesting the pathogen and its transmission to another person.

In France, transmissions have recently spread to new regions, including Alsace. At the end of June, a person who had not left their home region became infected near Strasbourg. The case had no further consequences as far as is known. The Robert Koch Institute (RKI) assessed it as a sign that the conditions for virus transmission are present in this region—and thus also on the German side of the Rhine.

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What is the situation in Germany?

So far, no case has been reported of a person in this country becoming infected with the virus. Theoretically, this would be possible if a person infected abroad encountered a local tiger mosquito. This has not seemed very likely so far. The tiger mosquito is only widespread in parts of Germany, found primarily in the southwest of the country. And the number of infected travelers returning from trips is still low. Over the past 20 years, between ten and 180 cases have been imported each year. This year, the number has been just over 100, according to the RKI database.

But the situation is changing due to the increasing spread of the pathogen and its vector mosquitoes. "The environmental conditions are currently favorable for local transmission of the Chikungunya virus in several European countries, including certain regions of Germany," says Celine Gossner. Hendrik Wilking, head of tropical infections at the Robert Koch Institute (RKI), warned at a press conference held by the Science Media Center: "We must expect to observe such local outbreaks in Germany, either this year or in the coming years."

Helge Kampen, head of the Laboratory for Medical Entomology at the Friedrich Loeffler Institute for Animal Health, expressed his views somewhat more cautiously at the event. He pointed to the still local tiger mosquito populations and the manageable sources of infection: "We're really still on a safe boat here." Nevertheless, he said, it would be wise for citizens in Germany to pay a bit more attention to mosquito protection, even in their own gardens, and, for example, to remove puddles of water.

For whom is the vaccination recommended?

The Standing Committee on Vaccination (Stiko) recently recommended vaccination for travelers traveling to areas currently affected by the virus. Immunization is also recommended for people who stay longer or more frequently in regions where the virus is endemic. The vaccine can be administered to people at least 12 years old.

The options include the live vaccine Ixchiq, which is more effective—measured by the number of antibodies produced—but also has slightly more side effects. The Stiko recommends it primarily for people who travel frequently or for longer periods to endemic areas. For one-time trips, the inactivated vaccine Vimkunya appears more advisable. Its effectiveness is somewhat lower, but it is also more tolerable.

Otherwise, standard mosquito protection is useful: body-covering clothing and mosquito sprays containing DEET, IR3535, or icaridin. Bed nets only protect people who sleep during the day, such as children or the elderly, from chikungunya.

And how should the outbreak in China be assessed?

Although the outbreak is neither the only nor the largest, César López-Camacho of the University of Oxford calls it significant. Around 8,000 people in Guangdong Province are now affected. At the same time, the biologist told the British Science Media Center: "It is extremely unlikely that a pandemic in the traditional sense will occur, as Chikungunya is not transmitted from person to person." The events in China are above all a reminder "that outbreaks can escalate rapidly when a virus enters a population that lacks immunity." This underscores the importance of continuous monitoring of the virus, as well as the availability of vaccines. "It is essential to prepare now to prevent larger, more destructive epidemics in the future."