Diagnosis Treatment And Vaccine

Mortality and morbidity from plague were significantly reduced in the 20th century. However, the disease has not been eradicated. Plague remains endemic in regions of Africa, Asia, and North and South America. From 1983 to 1997, there were 28,570 cases with 2331 deaths in 24 countries reported to the World Health Organization (WHO). In 1997 the total number of cases reported by 14 countries to the WHO was 5419, of which 274 were fatal. Epidemics occurred in Madagascar in 1991 and 1997, in Malawi, Zimbabwe, and India in 1994, and in Zambia and China in 1996. In contrast, there were four cases and only one death in the United States in 1997.

Though human disease is rare, a feverish patient who has been exposed to rodents or flea bites in plague endemic areas should be considered to be a possible plague victim.

Diagnosis can be made by Gram stain and culture of bubo aspirates or sputum. The bacteria grow aerobically and form small colonies on blood and MacConkey agar.

Unless specific treatment is given, the condition of a plague-infected individual deteriorates rapidly and death can occur in 3 to 5 days. Untreated plague has a mortality of more than 50%. A variety of antibiotics including streptomycin, sulfonamide, and tetracycline are effective against bubonic plague. Tetracycline can be used prophylactically, and chloramphenicol is used to treat plague meningitis. No antibiotic resistance has been reported.

Two plague vaccines have been approved for use in humans. One is a formaldehyde-killed, whole-cell vaccine first used in 1942, and the other is a live vaccine used in the former Soviet Union since 1939. A new subunit vaccine that uses the bacterial capsular antigens F1 and V for immunization is under development.

See Also the Following Articles

Blood Sucking • Medical Entomology • Siphonaptera • Zoonoses

Further Reading

Achtman, M., et al. (1999). Yersinia pestis, the cause of plague is a recently emerged clone of Yersinia pseudotuberculosis. Proc. Natl. Acad, Sci. U.S.A. 96, 14043-14048.

Carniel, E. (2000). Plague. In "Encyclopedia of Microbiology," (J.

Lederberg, ed.), Vol. 3, pp. 654-661. Academic Press, San Diego, CA. Herlihy, D. (1997). "The Black Death and the Transformation of the West."

Harvard University Press, Cambridge, MA. Hinnebusch, B. J. (1997). Bubonic plague: A molecular genetic case history of the emergence of an infectious disease. J. Mol. Med. 75, 645-652. McNeill, W. (1998). "Plagues and People." Anchor Books, New York. Perry, R., and Fetherston, J. (1997). Yersinia pestis—etiologic agent of plague. Clin. Microbiol. Rev. 10, 35-66. Zeigler, P. (1969). "The Black Death." Harper & Row, New York.

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