Other Bacterial Agents

OTHER BACTERIAL AGENTS

Yersinia pestis , the causative agent of plague, was responsible for the notorious Black Death epidemics of the Middle Ages. It is highly infectious, the death rate is high, and it kills fast. Bubonic plague is spread by fleas; the more dangerous pneumonic form is spread from person to person directly via the air. Around World War II, plague was in vogue. The Japanese apparently tested bubonic plague on prisoners and also tried small-scale airborne dispersal of infected fleas carrying plague on the Chinese. This had little effect—partly because plague was endemic in China and already in natural circulation. The British biological warfare center at Porton Down maintained large-scale plague cultures for several years following World War II. In the 1960s the United States apparently experimented with spreading plague among rodents in Viet Nam, Laos, and Cambodia, again with little effect. Needless to say, this is officially denied. Since then, plague seems to have gone out of fashion.

Other bacteria qualify as potential bacterial agents. Brucellosis, caused by Brucella , is a disease of cattle, camels, goats, and related animals. Brucellosis was developed as a biological weapon by the United States from 1954 to 1969, though the choice seems curious. In humans it behaves erratically, both in the time for symptoms to emerge and the course of the disease. Though human victims often fall severely ill for several weeks, it is rarely fatal, even if untreated. Tularemia , caused by Francisella tularensis , is a disease of rodents or birds that has a death rate of 5% to 10% in humans, if untreated. It is highly infectious and generally regarded as an incapacitating rather than a lethal agent. It is still considered a possible threat. Melioidosis, caused by the bacterium Burkholderia pseudomallei , is related to glanders ( Burkholderia mallei ). Glanders is a disease of horses, and melioidosis is a rare disease of rodents from the Far East that is spread by rat fleas. Despite the pseudo- in its name, melioidosis is more virulent than glanders and is fatal some 95% of the time in humans.