Experimental infection of Amblyomma aureolatum ticks with Rickettsia rickettsii

Emerg Infect Dis. 2011 May;17(5):829-34. doi: 10.3201/eid1705.101524.


We experimentally infected Amblyomma aureolatum ticks with the bacterium Rickettsia rickettsii, the etiologic agent of Rocky Mountain spotted fever (RMSF). These ticks are a vector for RMSF in Brazil. R. rickettsii was efficiently conserved by both transstadial maintenance and vertical (transovarial) transmission to 100% of the ticks through 4 laboratory generations. However, lower reproductive performance and survival of infected females was attributed to R. rickettsii infection. Therefore, because of the high susceptibility of A. aureolatum ticks to R. rickettsii infection, the deleterious effect that the bacterium causes in these ticks may contribute to the low infection rates (<1%) usually reported among field populations of A. aureolatum ticks in RMSF-endemic areas of Brazil. Because the number of infected ticks would gradually decrease after each generation, it seems unlikely that A. aureolatum ticks could sustain R. rickettsii infection over multiple successive generations solely by vertical transmission.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Dogs
  • Female
  • Guinea Pigs
  • Male
  • Rabbits
  • Rickettsia rickettsii / physiology*
  • Rocky Mountain Spotted Fever / microbiology
  • Rocky Mountain Spotted Fever / transmission
  • Ticks / microbiology*