A Chinese pharmaceutical factory has apparently leaked an illness into the air and infected thousands of people, Global News reports. Chinese officials say the factory was producing vaccines for animals with brucellosis—also known as Malta fever or Mediterranean fever—when bacteria vented out and infected at least 3,245 people in Lanzhou, the capital of Gansu province. CNN reports that another 1,401 residents have come back “preliminarily positive” among 21,847 tests in the city of 2.9 million. State-run media reported the problem late last year, but with low numbers, and the factory said eight workers had been “severely punished.” Now officials say it’s far worse than they realized.
Authorities blame expired disinfectants and sanitizers for the leak of Brucella, a bacteria that causes brucellosis. The disease is usually found in dogs, sheep, goats, pigs, and cattle, per the World Health Organization, but can infect people via the air or contaminated food. Initial symptoms include fatigue, fever, muscle pain, and headaches, but the CDC warns that certain effects—like depression, arthritis, and swelling of the heart, liver, or spleen—may never go away. Brucellosis has mostly been tamed by vaccines and prevention techniques, but occasional outbreaks are known to afflict livestock around the world. (Bison have been slaughtered at Yellowstone in an effort to curb the disease.)