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More than 3,000 people have been infected with a brucellosis, a highly contagious zoonotic bacterial disease, in Lanzhou in northwest China. Symptoms include headaches, muscle pains, fatigue and fever. 

Contaminated gas leak

The outbreak was caused by a 2019 leak of contaminated waste gas at a pharmaceutical plant that manufactures animal vaccines. The firm was found to be using expired disinfectants, allowing residual bacteria to be released through exhaust gasses.

It is thought the leak began in late July and continued until late August last year. In December, it was reported that 181 people at a nearby veterinary research facility had been infected, and in January, authorities revoked the plant’s vaccine production licence. The full scale of the outbreak has not been widely reported until now. 

More cases expected

In addition to the confirmed 3,245 cases, another 1,401 residents have tested ‘preliminarily’ positive for brucellosis, and more cases are expected. No deaths have yet been linked to the outbreak, but those infected can experience long-term complications, such as arthritis. 

Brucellosis transmission

Zoonotic diseases have been in the global spotlight since the start of the COVID-19 crisis. 

While brucellosis can be transmitted from person-to-person, it is usually acquired via contact with farm animals, or by consuming infected milk or meat.