Prevalence of rickettsia-like organisms and spotted fever group rickettsiae in ticks (Acari: Ixodidae) from Zimbabwe.

The prevalence of rickettsia-like organisms in ticks from Zimbabwe was determined using the hemolymph test. Amblyomma hebraeum had the highest prevalence of rickettsia-like organisms. Other species with rickettsia-like organisms included Amblyomma sparsum, Amblyomma variegatum, Hyalomma marginatum rufipes, Ripicephalus simus, Haemaphysalis leachi, Amblyomma rhinocerotis, and Hyalomma truncatum. Ticks with no demonstrable rickettsia-like organisms infection were Boophilus decoloratus, Haemaphysalis spinulosa, Rhipicephalus appendiculatus, Rhipicephalus evertsi evertsi, and Rhipicephalus sanguineus. Polymerase chain reaction followed by restriction fragment-length polymorphism analysis on samples of hemolymph-positive ticks showed the agent of African tick-bite fever to be present in A. hebraeum, Rickettsia conorii to be present in Rhipicephalus simus and Haemaphysalis leachi, and a spotted fever group rickettsia similar to that in Hyalomma marginatum marginatum ticks from Morocco and Portugal to be present in Hyalomma marginatum rufipes.