A mosquito-borne virus outbreak has infected more than 7,000 people across at least 13 cities in China, prompting authorities to introduce strict precautions reminiscent of the COVID pandemic—even though the virus cannot be transmitted from person to person.

The chikungunya virus, which is only spread through the bite of an infected mosquito and is rarely fatal, has moved quickly through more than a dozen cities in southern Guangdong province, just north of Hong Kong. Almost 3,000 cases were reported in the past week alone, according to the BBC.

Chikungunya is usually rare in China, but infections surged after an imported case was detected in Foshan city on July 8, which has since become the hardest-hit area, according to the New York Times.

In response, authorities in Guangdong have rolled out measures similar to those used during the COVID pandemic. All infected patients are required to stay in hospital quarantine under a mosquito net until they test negative for the virus, according to a translation of Chinese news outlet NF News.

Officials are also conducting door-to-door inspections to make sure stagnant water—where mosquitoes breed—is removed. Those who fail to cooperate can be fined or face criminal charges for “obstructing the prevention of infectious diseases,” according to a government flyer translated by the Times.

Other precautions include introducing giant “elephant mosquitoes” whose larvae eat virus-carrying mosquitoes, releasing mosquito-eating fish into local ponds, spraying pesticides and deploying drones to identify mosquito breeding sites, the Times reported.

What is chikungunya?
Chikungunya is a mosquito-borne virus that most often causes headache, muscle pain, nausea, fatigue, rash and swollen joints. While most symptoms resolve within two weeks, the “debilitating” joint pain can last for months or even years, according to the World Health Organization. The joint pain is considered the signature symptom of chikungunya. Without it, infected people may be misdiagnosed with dengue or Zika, making it difficult to know how many people actually have chikungunya. First detected in southern Tanzania in the 1950s, its name comes from a Kimakonde word meaning “that which bends up,” describing the contorted posture caused by severe joint pain.

How does it spread?
Chikungunya can only be transmitted through a mosquito bite. However, people with the virus can pass it back to non-infected mosquitoes if bitten, allowing those insects to then infect others. The virus is not contagious between people.

Is there a vaccine?
There are two vaccines approved for use in the United States: IXCHIQ (for those 18 and older) and VIMKUNYA (for those 12 and older). The CDC recommends vaccination only for travellers heading to areas with active chikungunya outbreaks.

Where is chikungunya most common?
The Centers for Disease Control and Prevention warn that U.S. travellers visiting Brazil, Colombia, India, Mexico, Nigeria, Pakistan, Thailand and the Philippines are at increased risk. The CDC has also issued a Level 2 travel alert for Foshan city and recommends travellers be vaccinated before visiting. Preventive measures include using insect repellent and wearing long-sleeved shirts and trousers. Pregnant women are advised not to travel to affected regions.

What next?
Authorities expect more infections as Hong Kong reported its first case—a 12-year-old boy—on Monday.