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Plague Pneumonia -- California

On March 30, 1984, a 35-year-old Claremont, California, veterinarian had onset of an illness subsequently identified as bubonic plague with secondary plague pneumonia. This is the first person since 1924 to acquire plague pneumonia infection in Los Angeles County, California. Claremont is within 10 miles of the area where a human case of bubonic plague was identified in May 1979. The veterinarian became ill with fatigue and fever on March 30 and developed a cough on March 31. On April 2, he consulted a private physician complaining of a tender left axilla and forearm. No enlarged lymph nodes or bite sites were identified. He was placed on cefadroxil, 500 mg twice daily. He returned to his physician the next morning with a painful, edematous left upper arm. Axillary vein thrombosis was diagnosed, and he was hospitalized.

Antibiotic therapy with a cephalosporin was continued intravenously. On April 4, he complained of chest pain, cough, and shortness of breath. A chest radiograph revealed bilateral pulmonary infiltrates. A diagnosis of plague was considered, and appropriate antibiotic therapy and respiratory isolation precautions were begun. Fluorescent antibody testing of a lymph-node aspirate was positive for Yersinia pestis on April 5; a smear from a lymph-node aspirate showed bipolar staining, gram-negative organisms suggestive of Y. pestis. The organism was also isolated from blood and a bubo aspirate and seen on a sputum smear. By April 7, the patient had pleocytosis and signs of meningeal irritation. Chloramphenicol was added to the antibiotic regimen. On April 9, the patient was in stable condition.

Sixty-one persons who had face-to-face contact with the patient after he began coughing were considered to be at risk; they included two family members, one office associate, the physician and two of his staff, and 55 hospital contacts. All adults were treated with tetracycline, the drug of choice for plague prophylaxis, and advised to monitor their temperatures daily for 7 days. One pregnant woman and one child were treated with trimethoprim/sulfamethoxazole. A co-worker of the patient was already on tetracycline for another condition. No secondary cases have occurred, and active surveillance in surrounding hospitals has not identified any other cases.

The patient, who has a small-animal practice, denied contact with wild animals or travel outside his local area. He had no history of a needlestick injury or cut during surgery or other procedures. His office and home environment were investigated as potential sources of infection. Office records and charts of all animals seen by the veterinarian during the week before onset of symptoms were evaluated. Only one animal, cat A, had an illness with symptoms compatible with those usually seen with pneumonic plague (difficulty breathing and hemoptysis) but had no fever. The cat died, and its body was not available for autopsy. No suspicious illnesses among neighborhood animals or owners were noted, but 51 pet owners were contacted and advised to disinfest their pets and to avoid contact with ground squirrels and other rodents.

Despite significant roof-rat activity at the veterinarian's residence during 5 days of trapping by the Los Angeles County Vector Control, no rodents were caught, and no signs of rodent die-off were found. The patient had gardened 5 days before onset of his illness. Serum samples from four of the veterinarian's animals--a household pet rabbit and dog, plus a cat (cat B) and dog from the office--tested for antibody to Y. pestis were negative. After the negative surveillance serum was collected from cat B, it developed a febrile illness and was treated with antibiotics; a convalescent serum from cat B had a titer of 512 to Y. pestis. This animal had contact with cat A, which was believed responsible for the veterinarian's infection. Evidence of epizootic die-off of rodents was found in the area in which cat A lived. Several dogs, cats, and coyotes were bled from that area and exhibited antibody to Y. pestis. Reported by B Johnson, J Almas, MD, M Salkin, MD, G Sidana, MD, Pomona Valley Hospital, A Tilzer, F Hall, M Canlas, MD, K Hunt, S Fannin, MD, M Tormey, MPH, L Habel, MPH, F Sorvillo, MPH, J Marron, DVM, P Ryan, DVM, County of Los Angeles Dept of Health Svcs, B Nelson, MD, M Madon, C Meyers, Vector Biology and Control Br, J Chin, State Epidemiologist, California State Dept of Health Svcs; Plague Br, Div of Vector-Borne Viral Diseases, Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: Veterinarians and their assistants engaged in small-animal practices in plague enzootic areas have a definite risk of exposure to plague infection from their free-roaming patients. Since 1959, four veterinarians and one veterinary assistant have had confirmed plague infections; one veterinarian in Santa Clara County, California, died. The veterinary assistant (Cheyenne, Wyoming) developed primary plague pneumonia after exposure to a terminally ill cat, subsequently confirmed to have plague pneumonia. Additionally, there have been reports of dogs and cats associated with the acquisition of plague by 20 other persons since 1959, demonstrating the increasing awareness of the role of pet carnivores in the epidemiology of human plague (1,2).

Lung involvement is possible with bubonic or septicemic plague. Since 1975, 32 (17%) of 188 human plague patients have had plague pneumonia. Four of these were primary plague pneumonias acquired from sick pet cats (3) or a pet dog (1); the remaining 27 cases involved pneumonic involvement secondary to bubonic or septicemic plague. Prevention of plague pneumonia is best achieved by rapid diagnosis of plague concomitant with rapid initiation of specific antibiotic therapy.

Over 2,000 people have been placed on prophylactic antibiotics following exposure to patients with suspected or known plague pneumonia; others have been placed on disease surveillance (3). To date, no person-to-person spread of plague from a patient to his or her contacts has been reported.

Health-care personnel should take care of patients with evidence of respiratory involvement during illnesses compatible with plague using appropriate isolation precautions (4,5). The onset of cough on the second day of illness in this patient, followed by clinical evidence of pneumonia 4 days later, raised the question of his infectivity during the 4 days before hospitalization. An extremely careful historic and clinical evaluation or a chest radiograph during the first 5 days of illness may have provided information regarding his potential communicability. In this situation, the necessity to determine his exact period of infectivity was not crucial, since all his contacts were identified and treated with prophylactic antibiotics. This is in contrast to a situation occurring in 1976 when a 15-year-old male ill for 4 days developed clinical evidence of plague pneumonia 2 hours after being hospitalized. Twenty-four hours before hospitalization, he had attended a community church meeting. Since tracking his possible contacts at that meeting would have been an enormous task, it was crucial to correctly determine which of his contacts were at risk (6,7).

Since 1978, additional plague infections acquired in Los Angeles County and elsewhere have been diagnosed in Los Angeles County. Thus, Los Angeles--and the entire southern California area--are "susceptible" to the occurrence of human plague, whether indigenously acquired or imported, and the medical communities of the area and the nation should remain alert to the potential for plague in persons with compatible epidemiologic features.


  1. Kaufmann AF, Mann JM, Gardiner TM, et al. Public health implications of plague in domestic cats. Am J Vet Med Assoc 1981;179:875-8.

  2. Rollag OJ, Skeels MR, Nims LJ, Thilsted JP, Mann JM. Feline plague in New Mexico: report of five cases. Am J Vet Med Assoc 1981;179:1381-3.

  3. Poland JD. Plague. In: Maxey and Rosenenau. Public health and preventive medicine, 12th Edition. JM Last, Ed. (In press)

  4. White ME, Gordon D, Poland JD, Barnes AM. Recommendations for the control of Yersinia pestis infections. Infect Control 1980;1:326-9.

  5. Garner JS, Simmons BP. Guideline for isolation precautions in hospitals. Infect Control 1983;4:245-325.

  6. CDC. Plague activities. Vector-Borne Diseases Division, Report Part II, 1976.

  7. CDC. Human plague--Arizona, California, New Mexico. MMWR 1976;25:155.

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