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Surveillance Summary Human Plague -- United States, 1981

For 1981, 13 cases of human plague, 4 of them fatal, were reported from 5 states: Arizona (4), California (1), Colorado (1), Oregon (1 fatal), New Mexico (6, 3 fatal) (Figure 2). Twelve cases were confirmed at CDC by fluorescent antibody testing and by bacteriologic identification and characterization; 1 case was confirmed serologically. The patients ranged in age from 2 to 72 years with a mean age of 38.7 years. Seven patients (54%) were male, 6 were white, 6 were American Indian (5 Navajo, 1 Hopi), and 1 was Asian. The clinical manifestations included bubonic plague (5 patients), septicemic plague (5), septicemic with confirmed secondary pneumonic plague (2), and presentation unspecified (1).

The various modes of infection were flea bite (5 cases), skinning an infected bobcat (1), rabbit hunting (1), bite of an infected domestic cat (1), and undetermined (5). The 5 cases acquired by flea bite occurred in relation to epizootic plague among prairie dogs (Cynomys_gunnisoni) and rock squirrels (Spermophilus_variegatus). Two patients with unknown source of infection resided in areas where an epizootic of plague was occurring in prairie dogs.

From 1970 through 1981, enzootic and epizootic plague among rodents and carnivores was documented in 12 western states: Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Texas, Utah, Washington, and Wyoming. Human plague cases were reported from 8 of these states. The geographic distribution of 136 human cases in the period 1970-1981 is shown in Figure 3, and the totals by state for the same period are shown in Table 2. Reported by MM Ettenger, MD, Dept of Internal Medicine, Gallup Indian Medical Center, J Porvoznik, MD, Indian Health Svcs, MR Skeels, PhD, Scientific Laboratories Div, JM Mann, MD, Chief of Communicable Diseases, Epidemiology, and Control, Health Svcs Div, New Mexico Health and Environment Dept, New Mexico; J Leedom, MD, P Heseltine, MD, Los Angeles County USC Medical Center, SL Fannin, MD, Acute Communicable Disease Control, County of Los Angeles Dept of Health Svcs, J Chin, MD, State Epidemiologist, Dept of Health Svcs, California; JK Emerson, DVM, MPH, State Public Health Veterinarian, RS Hopkins, MD, State Epidemiologist, State Dept of Health, Colorado; LP Williams, Jr, DVM, MPH, State Public Health Veterinarian, Dept of Human Resources, Oregon; JJ Sacks, MD, State Epidemiologist (Acting), State Dept of Health Svcs, Arizona; Field Svcs Div, Epidemiology Program Office, Vectorborne Diseases Div, Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: Plague is a bacterial disease caused by the organism, Yersinia_pestis. It is usually contracted from the bite of an infected wild-rodent flea but can also occur as the result of direct contact exposure to infected rodents, rabbits, and carnivores. The infection can be spread from person to person by patients with pulmonary involvement with Y._pestis. Although this was most likely a major cause of rapid dissemination during great epidemics such as occurred in China (1), pneumonic plague is seen infrequently in modern times. Moreover, today plague pneumonia usually results from extension of septicemia to involve the lungs (secondary plague pneumonia) rather than from direct seeding of the lungs by inhaled organisms (primary plague pneumonia). Of 105 cases of human plague reported to CDC from 1970 to 1979, 82% were associated with an antecedent flea bite (2). In this same period, 19 cases (18%) of pneumonic plague secondary to septicemia were reported. Since 1925, only 1 case of primary pneumonic plague has been documented in the United States. This case occurred at Lake Tahoe, California, in 1980, and resulted from exposure to a kitten with plague pneumonia.

The geographic distribution of cases for 1981 generally reflects the same pattern seen since 1970. New Mexico and Arizona continue to be important foci for human cases. Possible explanations for this distribution are the exposure of American Indian populations to enzootic and epizootic plague foci through hunting and food-gathering activities and the growth of non-Indian populations and expansion of their residential areas into previously uninhabited areas of enzootic plague. Faulty environmental sanitation and premises management may also play a role by providing sites for harboring rodents (3).


  1. Wu L-T. A treatise on pneumonic plague. Strasburg: Berger-Levrault, 1926.

  2. Kaufmann AF, Boyce JM, Martone WJ. Trends in human plague in the United States. J Infect Dis 1980;141:522-4.

  3. Mann JM, Martone WJ, Boyce JM, Kaufmann, AF, Barnes AM, Weber NS. Endemic human plague in New Mexico: risk factors associated with infection. J Infect Dis 1979;140:397-401.

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