In humans, the bubonic plague kills about two out of three infected patients in 2–6 days without treatment. The latest research shows that the bubonic plague was the cause of the Black Death that swept through Europe in the 14th century and killed an estimated 75 million people, 30-60% of the European population. Because the plague killed so many of the working population, wages rose and some historians have seen this as a turning point in European economic development.
Signs and symptoms
The most famous symptom of bubonic plague is painful, swollen lymph glands, called buboes. These are commonly found in the armpits, groin or neck. Due to its bite-based form of infection, the bubonic plague is often the first step of a progressive series of illnesses. Two other types are pneumonic and septicemic. However, pneumonic plague, unlike the bubonic or septicemic, induced coughing, and was also very infectious and allowed person-to-person spread. Bubonic plague symptoms appear suddenly, usually 2–5 days after exposure to the bacteria. Symptoms include:
- Chills
- General ill feeling (malaise)
- High fever (102 degrees fahrenheit / 39 degrees celsius)
- Muscle pain
- Severe headache
- Seizures
- Smooth, painful lymph gland swelling called a bubo, commonly found in the groin, but may occur in the armpits or neck, most often at the site of the initial infection (bite or scratch)
- Pain may occur in the area before the swelling appears
Bubonic plague is an infection of the lymphatic system, usually resulting from the bite of an infected flea, Xenopsylla cheopis (the rat flea). The fleas are often found on rodents such as rats and mice, and seek out other prey when their rodent hosts die. 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. Y. pestis bacilli can resist phagocytosis and even reproduce inside phagocytes and kill them. As the disease progresses, the lymph nodes can haemorrhage and become swollen and necrotic. Bubonic plague can progress to lethal septicemic plague in some cases. The plague is also known to spread to the lungs and become the disease known as the pneumonic plague. This form of the disease is highly infectious as the bacteria can be transmitted in droplets emitted when coughing or sneezing, as well as physical contact with victims of the plague or flea-bearing rodents that carry the plague.In modern times, several classes of antibiotics are effective in treating bubonic plague. These include aminoglycosides such as streptomycin and gentamicin, tetracyclines (especially doxycycline), and the fluoroquinolone ciprofloxacin. Mortality associated with treated cases of bubonic plague is about 1-15%, compared to a mortality rate of 50-90% in untreated cases.Laboratory testing is required, in order to diagnose and confirm plague. Ideally, confirmation is through the identification of Y. pestis culture from a patient sample. Confirmation of infection can be done by examining serum taken during the early and late stages of infection. To quickly screen for the Y. pestis antigen in patients, rapid dipstick tests have been developed for field use.
Bubonic plague is believed to have claimed nearly 200 million lives, although there is some debate as to whether all of the plagues attributed to it are in fact the same disease. The first recorded epidemic ravaged the Byzantine Empire during the sixth century, and was named the Plague of Justinian after emperor Justinian I, who was infected but survived through extensive treatment.
It is generally held that the most infamous and devastating outbreak of bubonic plague was the Black Death, which killed a third of the population of Europe in the 14th century. In affected cities, proper burial rituals were abandoned and bodies were buried in mass graves, or abandoned in the street. The Black Death is thought to have originated in the Gobi Desert. Carried by the fleas on rats, it spread along trade routes and reached the Crimea in 1346. (It also spread eastward to the Yangtse river valley, and the resulting epidemic, ignored by the government, brought down the Yuan dynasty.In 1347 it spread to Constantinople and then Alexandria, killing thousands every day, and soon arrived in Western Europe.
Though bubonic plague is generally regarded as the probable pathogen responsible for the Black Death outbreak, there are significant differences between symptoms and spread of the Black Death and more recent bubonic plague outbreaks and several alternate theories of the Black Death have been proposed involving pathogens other than Y. pestis.
The next few centuries were marked by several local outbreaks of lesser severity. The Great Plague of Seville, 1649, the Great Plague of London, 1665–1666, the Great Plague of Vienna, 1679, and the Great Plague of Marseille, 1720, were the last major outbreaks of the bubonic plague in Europe.
A popular folk etymology holds that the children's game of "Ring Around the Rosy" (or Ring a Ring o' Roses) is derived from the appearance of the bubonic plague. Proponents claim that "Ring around the rosy" refers to the rosy-red, rash-like ring that appeared as a symptom of the plague. "Pocket full of posy" referred to carrying flower petals as at the time it was believed the disease was spread through the ether of unhygene, and scent stopped the spread. "Ashes, ashes" referred to the burning of infected corpses (in the UK the words of the rhyme are "atishoo, atishoo" mimicking sneezing), and "we all fall down" referred to the virulent deaths attributed to the plague.Many folklorists however hold that the association of this rhyme with plague is baseless.
In 1994 and 2010 there have been cases reported in Peru. In 2010 there was a case reported in Oregon, United States.
