HOHHOT, Nov. 28 (Xinhua) -- A new pneumonic plague case has been confirmed in Ulanqab, north China's Inner Mongolia Autonomous Region, after a herdsman was diagnosed Wednesday.

The city is over 500 km away from Xilingol League in the region, where the other three pneumonic plague cases were previously found.

The patient, who had visited a region where plague sources were identified, was being treated in isolation and was in a stable condition at the Siziwang Banner People's Hospital in Ulanqab, according to the hospital on Thursday.

Four people who had close contact with the patient have been isolated for medical observation as required. None of them have shown symptoms such as fever at present.

Siziwang Banner has completed comprehensive disinfection and sterilization of the patient's house and the surrounding pastoralists' dwellings. Local authorities are implementing rodent and flea control, and publicity work.

After the plague cases, the health department in Inner Mongolia has carried out investigations and rodent extermination.