As of Saturday noon, 96 people in a veterinary research institute in Lanzhou, northwest China's Gansu Province, were confirmed with brucellosis antibody-positive, local health authority said.

The authority said that 317 people at the institute had been tested, of which 96 were confirmed antibody-positive without obvious symptoms.

The patients have been under medical observation and will be given standard treatment, if necessary.

The local department of agriculture is investigating the source of the disease and carrying out monitoring work.

Brucellosis, also known as the Mediterranean fever, is an infectious bacterial disease caused by brucella, transmitted by contact with infected livestock including cattle and sheep. It's caused by ingestion of unpasteurized milk or undercooked meat from infected animals, or close contact with their secretions. It is characterized by fever, malaise and headaches. 

The local health commission said the risk of human-to-human transmission of brucella is minimal.

(With input from Xinhua)