Plague

CLINICAL FEATURES

  • Bubonic plague: enlarged, tender lymph nodes, fever, chills and prostration
  • Septicemic plague: fever, chills, prostration, abdominal pain, shock and bleeding into skin and other organs
  • Pneumonic plague: fever, chills, cough and difficulty breathing; rapid shock and death if not treated early

AETIOLOGIC AGENT

  • Yersinia pestis - bacillus

INCIDENCE

  • In the U.S., 1 to 40 cases reported annually (avg = 13 cases) by western states, 1971-1995
  • Worldwide, 2861 cases reported by 10 countries to WHO in 1995

SEQUELAE

  • Rare, consequences of disseminated intravascular coagulation, lung damage
  • Mortality 50-90% if untreated; 15% when diagnosed and treated

COSTS

  • Not known

TRANSMISSION

  • Flea-borne, from infected rodents to humans
  • Direct contact with infected tissues or fluids from handling sick or dead animals
  • Respiratory droplets from cats and humans with pneumonic plague

RESERVOIRS

  • Primarily wild rodents in U.S. (especially rock squirrels, ground squirrels, prairie dogs, other burrowing rodents)
  • Commensal rats may be important elsewhere

RISK GROUPS

  • In the U.S., persons exposed to rodent fleas, wild rodents, or other susceptible animals in enzootic areas of western states
  • Most cases occur in southwestern states of NM, AZ, CO, and in CA
  • Highest rates in Native Americans, especially Navajos; other risk groups: hunters; veterinarians and pet owners handling infected cats; campers or hikers entering areas with outbreaks of animal plague

SURVEILLANCE

  • National Notifiable Disease Surveillance System (NNDSS) for animal plague surveillance, for reports of human cases, and laboratory testing of fleas, animal tissues and serum specimens, and serosurveys of carnivores
  • CDC, Fort Collins, is a WHO Collaborating Center for Reference and Research on Plague Control, and reports all human plague cases in the U.S. to WHO

OPPORTUNITIES

  • Increased self-sufficiency of state and county public health labs
  • Expanded active surveillance through carnivore serosurveys and application of geographic information systems (GIS) to surveillance programs
  • Increased education of public and health professionals
  • Collaborative applied research on plague prevention and control with other federal, state, and local health agencies, including application of GIS to surveillance

RESEARCH

  • Ecology-based prevention and control strategies
  • Improved diagnostic reagents and methods
  • Risk factor identification using landscape ecology and epidemiology
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