Scientific American Experts say the painful infection, spread to people from mosquitoes, can get to many countries if it finds the right hosts. Thousands of cases of the chikungunya virus, which sickens people bitten by an infected mosquito, have broken out in China during the past week. The virus causes extremely severe joint pain and fever, both of which can be short-lived—but can sometimes continue for years. Chikungunya can sometimes cause heart damage. Three days ago, the U.S. Centers for Disease Control and Prevention issued a travel warning for the area of the outbreak (the province of Guangdong in southern China), advising people to take precautions. And experts warn that chikungunya could further spread in the Americas and parts of Europe, though cases there have been relatively rare compared with those in tropical regions. Here is what you need to know about the disease and the risk.
What is the chikungunya virus, and how do people get infected?
The virus was first identified in Africa in 1952. It is spread most often by two mosquito species: Aedes aegypti and Aedes albopictus. People can get sick within three to seven days of a bite. In 2025 about 240,000 cases and 90 deaths have been reported in 16 countries and territories through July. Cases have been reported in the Americas, Africa, Asia and Europe. Infection usually produces symptoms including deeply painful joints, fevers, nausea, fatigue and a rash. Most of the time these problems resolve in a week or two. “But sometimes they can continue for months and years, and the virus can also cause serious heart damage,” says Jean Lim, a microbiologist at the Icahn School of Medicine at Mount Sinai and a member of the Global Virus Network’s chikungunya task force. “In rare cases it can be fatal, and those most vulnerable are people who are immunocompromised, the elderly, and babies.”