Human ehrlichioses are emerging tick-borne zoonotic infectious diseases. Although Ehrlichia ewingii and E. canis, pathogens that typically cause canine ehrlichiosis, occasionally infect humans, the major forms of human ehrlichiosis are human monocytic ehrlichiosis (HME) and human granulocytic ehrlichiosis (HGE). The name for HGE has recently been changed to Human anaplasmosis due to transferring the causative agent to a different genus.
Various prevalences of the HME agent in ticks have been reported in the US (52% from Maryland, 29% from Missouri, 12 – 20% from California, and 1.4-4.9% from Indiana). Prevalences of the HGE agent in ticks have been reported from a number of northern states (e.g., 43-53% in New York, 50 % in Connecticut, 17% in New Jersey, and 12% in Wisconsin), but not from the southeastern region. In order to determine prevalences of both the HME and HME agents in ticks from the southeastern US, we collected ticks from field sites and screened them for HME and HGE using nested PCR techniques. Our results show that prevalences of the HME agent in Amblyomma americanum ticks range from 0 to 9.3% in the southeastern US, whereas prevalences of the HGE agent in Ixodes scapularis ticks range from 0 to 20%. The overall average prevalence of the HGE agent in questing adult I. scapularis from 15 collection sites was 1.6% (n=818).
Species 1: Acari Ixodidae Ixodes scapularis (black-legged tick)
Species 2: Acari Ixodidae Amblyomma americanum (Lone Star tick)
Keywords: ticks, ehrlichiosis
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