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A recent case of bubonic plague in Inner Mongolia has put what many people think of as a disease of the past back in the spotlight.
But the reality is that bubonic plague never went away -- cases occur regularly in Mongolia and many other parts of the world.
Chinese authorities are on alert for more cases, but health experts say the infection does not pose the same global threat it did in the 14th century when it claimed the lives of more than 50 million people during the Black Death.
Here’s what you need to know about the disease.
Plague is an infectious disease caused by the bacteria Yersinia pestis, which is carried by small animals, such as rats and squirrels, and the fleas that live on them.
The most common form of the disease is bubonic plague.
People with bubonic plague usually develop flu-like symptoms, such as fever, chills, vomiting, nausea and aches, 3 to 7 days after being infected.
Once a person is infected, the bacteria travel to glands in the body called lymph nodes, where they grow, and cause pain and inflammation. This swollen node is called a ‘bubo’, which is where the name of the disease comes from.
In some cases, the nodes may develop into open sores.
If the infection gets worse and spreads to the lungs, it can develop into a condition known as pneumonic plague. People with pneumonic plague may have shortness of breath, coughing and be coughing up blood.
Bubonic plague can also lead to blood poisoning (septicaemia) if the bacteria enter the bloodstream.
Your chances of catching plague are extremely small, but it’s possible if you’re bitten by an infected flea. This is the most common way people become infected.
People can also be infected if they come into contact with the blood of a dead animal. This can happen, for example, while skinning rabbits or squirrels.
Because bubonic plague is spread through flea bites or direct contact with animal blood, it’s rarely passed from person to person. But if it’s left untreated, spreads to the lungs and develops into pneumonic plague, the infection can be passed between people through droplets in the air.
There have been global outbreaks of plague in the past -- the most famous of which was the historic Black Death, which killed more than 50 million people during the 14th century.
It’s much less common today, but still occurs worldwide.
According to the World Health Organization (WHO), most cases today are reported in 3 countries: Madagascar, Democratic Republic of Congo and Peru. Madagascar reports cases of plague almost every year and a large outbreak in 2017 led to more than 2,400 cases.
Many other countries, including Mongolia and the USA, have cases of plague.
Records of the number of people infected are limited, but 3,248 cases were reported to the WHO between 2010 and 2015. This included 584 deaths.
Bubonic plague can be treated with antibiotics if it’s caught early enough. This is 1 of the reasons why an outbreak of plague today is unlikely to lead to the type of epidemic seen during the Black Death, as antibiotics didn’t exist in the 14th century.
People are less likely to reach the stage where the infection gets to the lungs and can spread to other people.
There’s also a vaccine for plague, but it’s only given to people at high risk of getting the infection as part of their job, such as healthcare workers and lab staff.
Plague is a serious infection that can kill 30% to 60% of people who catch it and don’t get treatment. The pneumonic form of the disease is always fatal without treatment.
Outbreaks of plague still occur in some parts of the world, but experts say it’s unlikely that any outbreak will become a global threat.
“While plague causes severe illness, if it is recognised promptly then it can be easily treated with antibiotics, and patients will make a full recovery,” said Jimmy Whitworth, Professor of International Public Health, London School of Hygiene & Tropical Medicine (LSHTM).
“Two cases of plague were identified in Beijing last year in travellers from Mongolia and were quickly treated, with no further spread of infection.”
Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.