Ehrlichia chaffeensis

DISEASE(S) AND SYMPTOMS

Ehrlichiosis

  • fever, malaise, headache, lymphadenopathy, anorexia

  • fever usually lasts 2 weeks

  • meningitis is occasionally reported

DIAGNOSIS

  • poor; few laboratories have antigen for immunoflourescence serology by surrogate E. canis antigen

INFECTIOUS AGENT

  • Ehrlichia chaffeensis, a rickettsia

  • reservoir is unknown

MODE OF TRANSMISSION

  • an undetermined tick transmits the agent (possibly the widely distributed species, Amblyomma americanum)

  • no evidence of person-to-person transmission

  • although other types of Ehrlichia are transmitted to dogs by the brown dog tick, dogs have not been found to be reservoirs of human disease

DISTRIBUTION

  • Southern and mid-Atlantic United States

INCUBATION PERIOD

  • unknown; possibly 1 to 3 weeks

TREATMENT

  • oral antibiotics: tetracycline

PREVENTION AND CONTROL

  • avoidance of tick-infested areas; securing of clothing at entry points (ankles, cuffs, etc.); application of tick repellent to outer clothing

FACTORS FACILITATING EMERGENCE

  • organism is probably newly recognized

  • possible increase in reservoir and vector populations



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