Beijing, Sep 18 (IANS): Amid the Covid-19 outbreak, now several thousand people in northwest China have tested positive for brucellosis, a bacterial disease, the authorities has confirmed recently.

The Brucellosis outbreak was caused by a leak at a bio-pharmaceutical company last year. According to the media reports, the disease, also known as Malta fever or Mediterranean fever, can cause symptoms including headaches, muscle pain, fever and fatigue.

While these may subside, some symptoms can become chronic or never go away, like arthritis or swelling in certain organs, as per the US Centers for Disease Control and Prevention (CDC).

Human-to-human transmission is extremely rare, according to the CDC. Instead, most people are infected by eating contaminated food or breathing in the bacteria -- which seems to be the case in Lanzhou.

According to CNN, the Health Commission of Lanzhou, the capital city of Gansu province, confirmed that 3,245 people had contracted the disease, which is often caused by contact with livestock carrying the bacteria brucella.

Another 1,401 people have tested as preliminarily positive, though there have been no fatalities reported, the city's Health Commission said on Tuesday.

In total, authorities have tested 21,847 people out of the city's 2.9 million population.

This outbreak stemmed from a leak at the Zhongmu Lanzhou biological pharmaceutical factory, which occurred between late July to late August last year, according to the CNN.

While producing Brucella vaccines for animal use, the factory used expired disinfectants and sanitizers -- meaning not all bacteria were eradicated in the waste gas, the report said.