Authorities in a city of China’s Inner Mongolia issued a warning on Sunday, a day after a hospital reported a case of suspected bubonic plague.
Sunday’s warning follows four reported cases of plague in people from Inner Mongolia last November, including two of the deadlier variant of plague—pneumonic plague.
The bubonic plague, known as the “Black Death” in the Middle Ages, is a highly infectious and often fatal disease that is spread mostly by rodents.
What is a plague?
Plague is an infectious disease caused by Yersinia pestis, a zoonotic bacteria, usually found in small mammals and their fleas, says the World Health Organization (WHO)
People can contract plague if they are in bitten by infected fleas and develop the bubonic form of plague. Sometimes bubonic plague progresses to pneumonic plague when the bacteria reach the lungs.
What is the bubonic plague?
According to WHO, bubonic plague is the most common form of plague and is caused by the bite of an infected flea.
It says plague bacillus, Y pestis, enters at the bite and travels through the lymphatic system to the nearest lymph node where it replicates itself. The lymph node then becomes inflamed, tense and painful, and is called a ‘bubo’.
At advanced stages of the infection, the inflamed lymph nodes can turn into open sores filled with pus. Human to human transmission of bubonic plague is rare.
What’s the difference between bubonic and pneumonic plagues?
Bubonic plague is the most common form of the plague but cannot be easily transmitted between people. Some people with bubonic plague will develop pneumonic plague.
Pneumonic plague, or lung-based plague, is the most virulent form of plague and has an incubation period as short as 24 hours. A person with pneumonic plague may transmit the disease to others through coughing via droplets.
Bubonic plague has a mortality rate of 30% to 60%, while the pneumonic form is fatal in the absence of treatment. Both types have good recovery rates if people are treated in time.
Pneumonic plague, if not diagnosed and treated early, can be fatal. However, recovery rates are high if detected and treated in time—within 24 hours of the onset of symptoms.
How are people infected?
Humans can be infected through the bite of infected vector fleas, unprotected contact with infectious bodily fluids or contaminated materials to the inhalation of respiratory droplets/small particles from a patient with pneumonic plague.
Can there be human to human transmission?
Person-to-person transmission is possible through the inhalation of infected respiratory droplets of a person who has the pneumonic plague. Common antibiotics are efficient to cure plague, if they are delivered very early because the course of the disease is usually rapid.
What are the symptoms?
People infected with plague usually develop acute febrile disease with other non-specific systemic symptoms after an incubation period of one to seven days.
Symptoms typically include sudden onset of fever, chills, head and body aches, weakness, vomiting and nausea. Painful and inflamed lymph nodes can also appear during the bubonic plague.
Symptoms of the pneumonic form appear quickly after infection, sometimes less than 24 hours, and include severe respiratory symptoms such as shortness of breath and coughing, often with blood-tainted sputum.
How is plague treated?
Plague can be treated with antibiotics, and recovery is common if treatment starts early. In areas where there is a plague outbreak, people with symptoms should go to a health centre for evaluation and treatment.
Patients with pneumonic plague must be isolated and treated by trained medical staff wearing personal protective equipment.
Can dead bodies spread plague?
The body of someone who has died after being infected with plague can infect people who are in close contact, such as those who are preparing the body for burial. The source of infection is the bacteria that are still present in body fluids.
When has it happened in the past?
Bubonic plague, known as the Black Death in the Middle Ages, killed tens of millions of people around the world in three major pandemics, with about a third of Europe’s population wiped out in the 1300s.
The bacterium is believed to have originated in Yunnan in southwest China. Opium trade routes from Yunnan caused the third global plague outbreak in 1894, but it has since become increasingly rare.
There were 3,248 cases worldwide, leading to 584 deaths—a fatality rate of 18%— between 2010 and 2015 according to WHO.