All Posts Tagged With: "monocytic ehrlichiosis; Ehrlichia ewingii"

Excerpt:

In this study, we evaluated Amblyomma americanum (lone star tick)
in Mississippi for the presence of Ehrlichia chaffeensis,
causative agent of human monocytic ehrlichiosis; Ehrlichia
ewingii, causative agent of human and canine granulocytic
ehrlichiosis; Borrelia lonestari, putative agent of southern
tick-associated rash illness; Francisella tularensis, the agent
of tularemia; and Rickettsia spp., particularly R. amblyommii, a
suspected pathogen. We collected adult A. americanum from four
regions of Mississippi: Northeast, Northwest, Southeast, and
East. Of the ticks collected, 192 were dissected and DNA was
extracted for nested polymerase chain reaction (PCR) assays to
detect the above bacteria. In all, 3% of tick extracts had
evidence of Borrelia sp., 4% for E. chaffeensis, 6% for E.
ewingii, and 44% for a Rickettsia species. As determined by
sequencing, most Rickettsia spp. were R. amblyommii. In addition,
extracts from 42 pools (total of 950) of larval A. americanum
collected in Southwest Mississippi were tested for the presence
of E. chaffeensis and Rickettsia species. Of these extracts from
pools, nine of 37 (24%) were PCR positive for a Rickettsia sp.,
most often, R. amblyommii; none had evidence of E. chaffeensis,
supporting the ability of lone star ticks to transovarially
transmit R. amblyommii, but not E. chaffeensis. This study
demonstrates E.