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Reason for surge in plague cases remains unknown
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A recent report in MMWR, detailing the 12 cases of human plague reported this year, noted that the reason behind the surge remains unclear.
“Plague is a rare, life-threatening, flea-borne zoonosis caused by the bacterium Yersinia pestis,” researcher Natalie Kwit, DVM, an epidemic intelligence service officer at the CDC, and colleagues wrote. “During 2001-2012, the annual number of human plague cases reported in the United States ranged from one to 17 (median = three cases). It is unclear why the number of cases in 2015 is higher than usual.”
From April 1 through Aug. 27, there have been 12 reported cases of plague from seven states. Plague has been consolidated in the western U.S., with four patients residing in Colorado, two in Arizona, two in New Mexico, one in California, one in Oregon and one most recently in Utah. Georgia is the only Eastern state to report a plague-infected resident, although that case has been linked to an exposure near Yosemite National Park in California.
Of the cases reported this year, four, all males, were fatal. They include a child and three adults aged 52 years and older. Six other cases involved boys and men.
Figure 1. 2015 cases of plague by state.
Source:MMWR
The CDC researchers said by using antibiotics, mortality associated with plague has declined from 66% (1900-1941) to 16% (1942-2012). Doctors in plague endemic areas are advised to consider the illness as a diagnosis in patients displaying symptoms of sudden onset of fever and malaise, with accompanying abdominal pain, nausea and vomiting. The CDC requires that all suspicions of plague be reported immediately to health officials.
“Persons engaging in outdoor activities in areas where plague is endemic should wear long pants when possible and use insect repellent on clothing and skin,” Kwit and colleagues wrote. “Persons also should avoid direct contact with ill or dead animals and never feed squirrels, chipmunks or other rodents.” – by David Costill
Reference:
Utah Department of Health Press Release.
Disclosure: The researchers report no relevant financial disclosures.
Perspective
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Janine K. Runfola
John M. Douglas, Jr.
The article by Kwit et al reported 11 cases of human plague in the United States from April through August, 2015. The reason for this increase is unclear, but it does mean that health care providers seeing persons with recent travel to endemic areas who have illness compatible with plague must keep this infection in their differential diagnosis. The most common form of plague is bubonic, which is not spread person-to-person. However, when a plague infection is left untreated in a person or animal the infection can progress to other forms such as septicemic or pneumonic, which have higher mortality rates. Plague pneumonia is particularly concerning because it has the potential to spread person-to-person or animal-to-person, and when unrecognized, health care workers are at risk for exposure and infection.
Laboratory diagnosis of plague is based on culture or polymerase chain reaction assays of blood, sputum or lymph node aspirates, or on serology. Clinicians should be aware that misidentification of the organism may occur if an automated culture identification system is used by the laboratory. Patients with possible pneumonic plague should be isolated and placed on droplet precautions. All patients suspected of plague should be treated with appropriate antimicrobial therapy (e.g., aminoglycosides, fluoroquinolones or doxycycline) as soon as possible after the laboratory specimens are taken since prompt treatment dramatically improves outcomes. Since the introduction of antibiotics the mortality from plague infections has decreased from 66% to 16%.
Local and state health departments should be notified immediately if a plague case is suspected, even prior to laboratory results being reported. Family members, medical personnel and other persons with close contact to a plague patient should be evaluated for potential exposure by public health officials. Depending on the type and timing of the exposure, contact recommendations can include antibiotic prophylaxis or fever watch without treatment. Laboratorians should also be assessed for aerosol exposures to plague.
When plague epizootics occur humans are at risk of infection. Reporting animal die-offs and veterinary cases of plague to public health officials plays an important part in finding and stopping the source of human infections. Timely identification of Yersinia pestis and notification to public health officials can decrease mortality and help prevent human outbreaks.
Janine K. Runfola, MS
Disease intervention specialist
Tri-County Health Department in Colorado
John M. Douglas, Jr., MD
Executive director
Tri-County Health Department in Colorado
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