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Chapter 24


Plague! The very word still strikes fear in the hearts and minds of all who hear it, especially if they have read the vivid accounts of the terrible pandemics which swept across continents on numerous occasions in the past, killing millions in scattered portions of' the globe. No doubt many epidemics were never recorded, but one of the earliest references to the plague was in 525 A.D. during the reign of the Roman emperor Justinian, when "many dropped down from a sudden vomiting of blood."

The greatest of these world pandemics were the Black Death, which spread across Europe in the 14th century, killing 25 to 33% of the entire population, and the Great Plague of 1665, which ravaged England; countless people died during these epidemics. In London, during one week of August, 1665, plague killed 4,232 people, exceeding the second commonest case of death listed --“fever” -- by more than twelve-fold. A third great pandemic began in China in 1860, reaching Hong Kong in 1894, where the causative organism was first isolated by Alexandre Yersin, after whom it is now named. The pandemic spread by infected rats on board ships to Southeast Asia, India (where up to ten million people died by 1919), sub-Saharan Africa, and the Americas. The infection was then transmitted to sylvatic rodents, which led to its propagation in rural areas of those continents, which today constitute many of the world’s remaining foci of plague.

But plague is not just a matter of distant history. There have been several outbreaks in this century, including minor ones in San Francisco in 1903 and Los Angeles in 1924-1925, and serious epidemics in eastern Asia (China, Manchuria, and Mongolia) in 1910-1911 and again in 1920-1921. During the war in Southeast Asia in the 1960s and early 1970s, plague had a resurgence in Vietnam, peaking at over 4000 cases per year.

The spread of most of these prior epidemics occurred along trade routes, both overland and shipping, the disease being carried from one port to another by rats, particularly in grain. The coming of the plague was heralded by the sight of dead rats, first the brown sewer rats, then the domestic black rats. In medieval homes or warehouses, rats fell from the rafters as they died, a sure sign of impending doom for families or workers below. Fortunately, after stricter international control measures were implemented at the turn of the century, the danger of plague spread by ships or other cargo carriers has been considerably reduced.

Even more fortunate has been the dramatic effect of antibiotic therapy on the mortality rate from plague, which in the past two decades has fallen to around 10% from pre-antibiotic era rates of 50 to 95%. Mortality may be only 5% in patients with uncomplicated bubonic plague, but the prognosis worsens considerably with primary or secondary septicemic or pneumonic plague without adequate early treatment; primary plague pneumonia is invariably fatal if antibiotic therapy is delayed for over 24 hours.


Plague. Bubonic plague. Oriental plague. Pestilence. Pestis major. Pest. Black Death. Sp: Peste. Plaga. Fr: Peste. Ger: Pest (Schwarzer Tod). Seuche.

Bubonic plague is also known as zoonotic plague, septicemic plague as pestis siderans, and pneumonic plague as demic plague. Sp: Peste bubonica. Fr: Bubonique. Ger: Beulanpest.


Plague is an acute febrile infection caused by Yersinia (Pasteurella) pestis. There are three clinical and pathological forms of plague, all caused by this organism: bubonic plague, and septicemic plague, and pneumonic plague.

Plague is also described as sylvatic, when it occurs in nature independent of human populations, and as domestic when it is associated with man and the rodents living in his surroundings.

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Copyright: Palmer and Reeder