(CNN) -- A Chinese town has been on lockdown since last week after a man died of the plague.
On the same day of the patient's death, a quarantine zone was set up, affecting at least 30,000 people living in Yumen city in China's northwestern Gansu province. The original quarantine period is set for nine days.
The deceased had been in contact with a dead marmot, a small furry animal in the squirrel family, according to Xinhua. He had chopped up the dead animal to feed to his dog, reports the AFP. It is not known whether the dog became infected.
The plague is a severe bacterial infection of the lung that affects rodents, some animals, and humans. Caused by the same bacteria that leads to the bubonic plague, the pneumonic type is considered more rare but more dangerous as it can be transmitted between humans through inhalation, without the involvement of animals.
The China Daily said four quarantine sectors had been set up in Yumen and 151 people who had come into close contact with the deceased patient are under medical observation. None of them have reported any symptoms so far, according to Xinhua.
The Center for Disease Control and Prevention in the U.S. says when plague is left untreated, all forms of the disease will rapidly progress to death. Antibiotics that fight the plague bacteria should be given to a patient within 24 hours of the first symptoms.
The plague occurs in many places in the world today, including Africa, North and South America and Asia.