Rickettsia africae

• Causes African tick-bite fever (ATBF)
• Carried by Amblyomma hebraeum and A. variegatum ticks in sub-Saharan Africa and the West Indies
• Most frequently-imported rickettsiosis

Clinical Manifestations

• Most common symptoms include fever, headache, and myalgias, with a black eschar ("tache noire")
  • Often have regional lymphadenopathy
  • Can have multiple eschars
• Rash less common
• Subacute neuropathy

Diagnosis

• Serology is the mainstay of diagnosis, but may need paired acute and convalescent serologies demonstrating a fourfold rise in titres
  • Compared to other Rickettsiae, antibodies appear late in convalescence
• May see organism in skin biopsy
• May be able to PCR blood, skin biopsy, or eschar base swabs

Management

• Treated with doxycycline 100 mg PO bid for 7 to 10 days
• Alternatives include chloramphenicol, azithromycin, and clarithromycin