10 things you need to know about Bubonic Plague

Fig: Plague in British India 

1. What's all the hype about bubonic plague?

Fig: A map of China

China has sounded an alert after a suspected case of the bubonic plague was reported in Bayan Nur, in the northern Inner Mongolia Autonomous Region. A level III warning of plague prevention and control has been issued, the state-run People’s Daily Online reported.

2.How did it spread to China? 

Fig:A Marmout (a Squirrel like animal)

The path by which it has spread to china is unclear. However, the alert asks people to immediately report any sick or dead marmot (large and heavy rodents that resemble squirrels), and forbids the hunting and eating of animals that could carry the plague. Five days before, Chinese news agency Xinhua had reported two suspected cases of bubonic plague in Khovd province in western Mongolia—two brothers had consumed marmot meat. 

News agency PTI quoted the local health authority as saying: “At present, there is a risk of a human plague epidemic spreading in this city. The public should improve its self-protection awareness and ability, and report abnormal health conditions promptly.” According to reports, the authorities announced that the warning period will continue until the end of 2020.

3.What is bubonic plague?

Fig:Electron micrograph of Yersinia pestis

Bubonic plague is one of three types of plague caused by bacterium Yersinia pestis.One to seven days after exposure to the bacteria, flu-like symptoms develop.These symptoms include fever, headaches, and vomiting.Swollen and painful lymph nodes occur in the area closest to where the bacteria entered the skin.Occasionally, the swollen lymph nodes may break open. 

4.How fatal is it? 

Fig:Burial during the second pandemic

In the Middle Ages, a bubonic plague pandemic, also known as the ‘black death’, had wiped out more than half of Europe’s population. However, with the availability of antibiotics, the disease is largely treatable now. If not treated on time, bubonic plague has a case-fatality ratio of 30 per cent to 60 cent, while its septicaemic (circulation in bloodstream) and pneumonic kind can touch 100 per cent fatality. If diagnosed and treated on time, the disease has about a 10 per cent fatality rate. 

5.What are its symptoms? 

Fig:Acral necrosis

 Sudden onset of fever, chills, head and body aches, and weakness, vomiting and nausea are some of tge symptoms. In bubonic plague, the lymph node becomes inflamed, tense and painful (almost the size of a chicken’s egg), called a ‘bubo’. At advanced stages of the infection, the inflamed lymph nodes can turn into open sores filled with pus. 

Fig:Groin buboes

The best-known symptom of bubonic plague is one or more infected, enlarged, and painful lymph nodes, known as buboes. After being transmitted via the bite of an infected flea, the Y. pestis bacteria become localized in an inflamed lymph node, where they begin to colonize and reproduce. Buboes associated with the bubonic plague are commonly found in the armpits, upper femoral, groin and neck region. When it advances to the lungs, pneumonic plague becomes the most virulent form of plague. Septicaemic plague (in bloodstream) can cause tissue death and subsequent neceosis of fingers, toes and nose. 

6.How does it transmit? 

Fig: An Oriental flea

Bubonic plague is an infection of the lymphatic system, usually resulting from the bite of an infected flea, Xenopsylla cheopis (the rat flea). In very rare circumstances, as in the septicemic plague, the disease can be transmitted by direct contact with infected tissue or exposure to the cough of another human. The flea is parasitic on house and field rats, and seeks out other prey when its rodent hosts die. The bacteria remain harmless to the flea, allowing the new host to spread the bacteria. The bacteria form aggregates in the gut of infected fleas and this results in the flea regurgitating ingested blood, which is now infected, into the bite site of a rodent or human host. Once established, bacteria rapidly spread to the lymph nodes and multiply. 

7.Dark history of plague

Fig:A plague doctor

Yersinia pestis has been discovered in archaeological finds from the Late Bronze Age. It resulted in ‘black death’, one of the worst pandemics in human history that claimed millions of lives in the 14th century. The disease is expected to have originated somewhere in Asia, spreading through China and India, before killing of an estimated two-thirds of the European population in the 1340s and 1350s. While antibiotics can now treat the disease now, the airborne spread of the highly contagious disease wreaked havoc and frenzy across the world; healthy people were found dead overnight, and sailors started arriving at ports either dead or rotting, or covered in black contusions, pus and blood. The disease is believed to have been brought under control by strict quarantine measures and public hygiene enactments.

8. How is it prevented?

Fig: Antibiotics (Doxycycline)

Prevention is through public health measures such as not handling dead animals in areas where plague is common.

Bubonic plague patients without secondary pneumonic and septicemic plague have a very low risk of spreading plague to close contacts. However, a patient with secondary or primary pneumonic plague can transmit Y. pestis to close contacts through coughing respiratory droplets. Within the first 24 h of the onset of pneumonic plague, the patient develops fever and quick heart rate without coughing and bloody sputum expectoration. This period is noninfectious .If a patient expectorates bloody sputum, it will be highly infectious . It is relatively easy to prevent pneumonic plague, because wearing a face mask or even covering one's mouth with a scarf can effectively prevent transmission. However, a patient with suspected pneumonic plague or bubonic plague with secondary pneumonic or septicemic plague should be isolated .

Except for physical prevention, antibiotic prophylaxis using tetracycline, streptomycin, and chloramphenicol is recommended . There is still no effective vaccine for plague prevention, although a live attenuated vaccine is used in some countries, such as China and Russia .

9. What is its epidemiology?

Fig: Body of a plague patient in Madascar

Globally between 2010 and 2015 there were 3248 documented cases, which resulted in 584 deaths.The countries with the greatest number of cases are the Democratic Republic of the Congo, Madagascar, and Peru.

For over a decade since 2001, Zambia, India, Malawi, Algeria, China, Peru, and the Democratic Republic of the Congo had the most plague cases with over 1,100 cases in the Democratic Republic of the Congo alone. From 1,000 to 2,000 cases are conservatively reported per year to the WHO.From 2012 to 2017, reflecting political unrest and poor hygienic conditions, Madagascar began to host regular epidemics.

10.Should we be affraid about a plague pandemic? 

Fig: Isolation of an infectious patient

No, there is no need to panic. With modern antibiotics if treatment is started early, the disease is treatable. But strict monitoring and enforcement of protocols must be practiced by local health authorities when new cases emerge. Also the patients must be isolated, investigated and the area must be decontaminated as soon as possible. 

To know about the plagues of India  click- here