So far this year, 13 cases of human plague have been reported in four states. This marks 2006 as the year with the largest number of reported cases in the United States since 1994.
According to the Centers for Disease Control and Prevention, the chief cause of the increase is thought to be related to the increased reproduction rates and survival of rodents and fleas in the southwestern United States in the past 2 years caused by wet, early springs and intervening cool summers (MMWR 2006;55:1–3). Human infection is usually acquired through bites from rodent fleas infected with Yersinia pestis.
The mean age of the 13 people infected with the plague was 43 years (range 13–79 years), and more than half (8) were female. The dates of illness ranged from Feb. 16 to Aug. 14, and most cases were reported in New Mexico (seven), followed by Colorado (three), California (two), and Texas (one). Two people died from the illness.
More than half of the cases (eight) were bubonic plague, while the rest were primary septicemic plague. Two patients developed secondary plague pneumonia.
Suspected modes of transmission among six of the patients summarized in the report included one who handled raw rabbit meat, one who skinned rabbit carcasses while hunting, and one who had a dog and a rock squirrel on her property with serologic evidence of past infection with Y. pestis.
The report advises clinicians to consider a diagnosis in patients who “have unexplained fever, suspected sepsis, or pneumonia with or without lymphadenopathy or a classic bubo, and live in or have traveled to a plague-endemic region” such as the western United States. Streptomycin and the tetracyclines are effective against the plague. The report noted that gentamicin and fluoroquinolones have been used successfully to treat the plague, but have not been approved by the Food and Drug Administration for this indication.