So far 3,245 people have tested positive for brucellosis, while a further 1,401 people are suspected to have the disease. Symptoms of the disease, also known as Malta fever or Mediterranean fever, include fever, headaches, muscle pain, and fatigue.

The outbreak comes after a leak at the Zhongmu Lanzhou biological pharmaceutical factory, thought to have taken place between late July to August last year. 

China’s state-run Global Times newspaper said: “The number is way larger than expected and raised widespread concern over the disease’s spread and its consequences.” 

The factory used expired disinfectants and sanitisers while producing Brucella vaccines for animals.

The contaminated waste gas then formed aerosols, which contained bacteria and leaked into the air. 

By November infections at the factory were rising and by the end of December at least 181 people tested positive for brucellosis, according to Chinese state-run news agency Xinhua.

Veterinary professor at Yangzhou University Zhu Guoqiang told Hong Kong’s South China Morning Post said: “It’s one of the most serious incidents because of the large number of people involved

“I’m not sure the bacteria they were exposed to in the exhaust air from the vaccine production process was as toxic as the ones found in patients who have been dealing with infected animals.” 

The possibility of human-to-human transmission is said to be extremely rare.

Most people are thought to be infected by eating contaminated food or inhaling the bacteria. 

Brucellosis is an infectious bacterial disease that spreads from animals to people.

It commonly occurs among dogs, sheep, cattle, goats and pigs. 

The news comes as China remains gripped in the middle of the COVID-19 pandemic as the invisible killer disease continues to spread in the country it originated in in December last year.

Mainland China reported nine new COVID-19 cases as of September 16, down from 12 reported a day earlier, the country’s national health authority said on Thursday.

The National Health Commission said in a statement all new cases were imported infections involving travellers from overseas. The number of new asymptomatic patients also fell to 14 from 16 a day earlier, though China does not count these patients as confirmed cases.

Total of confirmed COVID-19 cases in mainland China now stands at 85,223, while the death toll remained unchanged at 4,634.

More to follow…