Prevalence of Ehrlichia chaffeensis (Rickettsiales : Rickettsiaceae) in Amblyomma americanum (Acari : Ixodidae) from the Georgia coast and Barrier islands

Human monocytic ehrlichiosis is an emerging zoonosis caused by infection wi th Ehrlichia chaffeensis Anderson, Dawson, Jones & Wilson, which is transmi tted to mammals by ixodid ticks. Prevalence of infected ticks and distribut ion of infection foci indicate relative risk of human exposure to ehrlichio sis and may be influenced by factors such as geographic isolation, human di sturbance, and the availability of suitable mammalian reservoir hosts. To t est this, individual and pooled lone star ticks, Amblyomma americanum (L.), were collected fi om three populations from the Georgia coast (1 mainland site and two barrier islands) and screened for E. chaffeensis. A species-sp ecific, nested polymerase chain reaction (PCR) assay was used to amplify a 572 bp fragment of the E. chaffeensis 16S rRNA gene from infected ticks. PC R product specificity was confirmed by nucleotide sequencing. Our results s howed the prevalence of infected ticks to be 0.0% (n = 151), 0.9% (n = 111) , and 9.3% (n = 129) for Sapelo Island, St. Catherine's Island, and Fort Mc Allister, respectively.