Two people diagnosed with pneumonic plague in China

Authorities working to contain outbreak of disease that is worse than bubonic plague

Two people in China have been diagnosed with plague, the latest cases of a disease more commonly associated with historical catastrophe.

Plague is caused by the bacterium Yersinia pestis and can arise in three forms - a lung infection, known as pneumonic plague; a blood infection, known as septicemic plague; and a form that affects the lymph nodes, called bubonic plague.