The spotted fever group of Rickettsia consists of multiple species anging from microorganisms with unknown pathogenicity such s “Candidatus Rickettsia amblyommii” (hereafter R. amblyommii) o potentially lethal pathogens such as R. rickettsii, the causative gent of Rocky Mountain spotted fever (RMSF) in humans. Rickttsia amblyommii is found mainly in ticks belonging to Amblyomma enus, and report...

Investigation into the presence of C. ruminantium antigen, using an enzyme-linked immunosorbent assay (ELISA) in various tick tissues and haemolymph of adult Amblyomma hebraeum ticks revealed that the organism invades a number of body parts and can be demonstrated in A. hebraeum. In females, the gut, salivary glands, hypodermis and synganglion and in males, the salivary glands and gut showed th...

Six genera and 27 species of hard ticks (Ixodidae) currently are recognized in the United States east of the Mississippi River as follows: Amblyomma (4 species), Boophilus (1), Dermacentor (3), Haemaphysalis (2), Ixodes (16), and Rhipicephalus (1). We present a diagrammatic couplet key to the adults of the six genera and 27 species of Ixodidae found in the eastern portion of the United States.

Techniques for the rearing of Amblyomma species to be used in heartwater (Cowdria ruminantium) transmission experiments are discussed. These involve the breeding and maintenance of infected and non-infected strains of ticks. They include the feeding of ticks on sheep, rabbits, mice, tortoises and guinea fowl.

To determine the geographic distribution of the newly recognized human pathogen Rickettsia parkeri, we looked for this organism in ticks from Tennessee and Georgia, USA. Using PCR and sequence analysis, we identified R. parkeri in 2 Amblyomma americanum ticks. This rickettsiosis may be underdiagnosed in the eastern United States.

We detected Rickettsia africae, the agent of African tick-bite fever (ATBF), by amplification of fragments of gltA, ompA, and ompB genes from 3 specimens of Amblyomma loculosum ticks collected from humans and birds in New Caledonia. Clinicians who treat persons in this region should be on alert for ATBF.

Babesia bovis and Cowdria ruminantium were identified for the first time in cattle on Unguja Island, Zanzibar. B bovis is common and widespread, although clinical disease had not been diagnosed previously. The vector of heartwater, Amblyomma variegatum, is found throughout Unguja but C ruminantium appears to be more localised in distribution than B bovis.

Enterovirus-specific genetic sequences were isolated from two Amblyomma americanum tick pools. Identical genetic sequences were later obtained from cerebrospinal fluid of a patient with aseptic meningitis and a recent history of tick attachment. These observations suggest the possibility of an emerging tick-borne human enterovirus associated with aseptic meningitis.

We detected Rickettsia parkeri in 20%-33% of Amblyomma maculatum ticks sampled in North Carolina. Results highlight the high frequencies of R. parkeri-infected ticks in the state with the highest annual incidence of Rocky Mountain spotted fever. Epidemiologic studies are needed to definitively link R. parkeri to cases of spotted fever rickettsiosis.

To determine the cause of spotted fever cases in the southern United States, we screened Gulf Coast ticks (Amblyomma maculatum) collected in Arkansas for rickettsiae. Of the screened ticks, 30% had PCR amplicons consistent with Rickettsia parkeri or Candidatus Rickettsia amblyommii.