The possibility of bubonic plague and pneumonic plague being used as bioterrorism agents is discussed in an article published this week in The Lancet.
Professor Mike Prentice, of University College, Cork, Ireland, and Dr Lila Rahalison, of Institut Pasteur, Madagascar, did a comprehensive review of the genetic makeup of the plague, its transmission vectors, and potential use as a biological weapon. They also look at a number of historical outbreaks of the disease, including the Black Death.
Plague is caused by the bacterium Yersinia Pestis, which multiplies in the gut fleas which have fed on blood from infected aminals. This causes a blockage in the proventriculus the tube which connects the gut and the oesophagus of the flea. This blockage causes the flea to continually regurgitate and feed again, introducing Y. Pestis into the bloodstream of whatever it is biting rodent or human.
The onset of bubonic plague is sudden, and causes malaise, dizziness, high fever and swellings near the lymph nodes called "buboes", after two to six days incubation.
Patients who develop secondary plague pneumonia after fleabite can transmit pneumonic plague directly to others. This form of plague generally has a shorter incubation time (two to three days) and is characterised by sudden onset, high fever, pleuritic chest pain and a cough containing bloody sputum.
It is now possible to harness the ability of the plague to spread by respiratory droplets, and make aerosol-based weapons capable of causing widespread pneumonic plague outbreak. This and many other factors could combine to make Y. Pestis an attractive agent for bioterrorism its wide distribution, simple culture techniques, the high mortality rate of the associated pulmonary disease, availability of expert advice from former weapons scientists, or perhaps only the knowledge that many countries have investigated its use as a weapon.