The Health Commission of Lanzhou, capital of Gansu Province, confirmed that 3,245 people had contracted brucellosis, which is often caused by contact with farm animals that carry the bacteria Brucella.
Another 1,401 people tested tentatively positive, although no deaths have been reported, the city’s health commission said. In total, authorities tested 21,847 people out of 2.9 million people in the city.
Human-to-human transmission is extremely rare, according to the CDC. Instead, most people get infected by eating contaminated food or breathing in the bacteria ̵
The outbreak was caused by a leak in the biological pharmaceutical factory in Zhongmu Lanzhou, which occurred between late July and late August last year, according to the city’s health commission. Expired disinfectants and disinfectants were used in the factory in the manufacture of Brucella vaccines for animal use. This means that not all bacteria in the exhaust gas have been eradicated.
This contaminated exhaust formed aerosols containing the bacteria – and flowed into the air, carried by the wind to the Lanzhou Veterinary Research Institute, where the outbreak first occurred.
Other infected patients were Lanzhou University students and faculty members; The outbreak even spread to Heilongjiang Province on the northeastern tip of the country, where 13 positive cases had appeared at the veterinary institute as of August, Xinhua reported at the time.
A total of seven approval numbers for veterinary medicinal products have been deleted from the plant.
In February, the factory publicly apologized and said it had “severely punished” eight people believed to be responsible for the incident. It added that it would work with local authorities on the response and clean-up work and contribute to a compensation program for those affected.
The Lanzhou Health Commission also announced in its report on Tuesday that 11 public hospitals would offer free and regular checkups for the infected patients. The report did not provide any additional details on patient compensation other than that it should be released in batches from October.