AMBLYOMMA-AMERICANUM - A POTENTIAL VECTOR OF HUMAN EHRLICHIOSIS

Polymerase chain reaction primers specific for Ehrlichia chaffeensis w ere used to amplify DNA from extracts of pooled ticks. Amplification w as performed on extracts from 140 pools (1,579 total ticks) consisting of three tick genera collected from five states. The characteristic 3 89-basepair product was observed after amplification of extracts from seven different pools of adult Amblyomma americanum (117 pools, 1,462 ticks), but not from pools of nymphs. No specific product was observed after amplification of 20 pools (105 ticks) of Dermacentor variabilis and three pools of Ixodes scapularis (12 ticks). Ehrlichia chaffeensi s was present in A. americanum at a minimum frequency of greater-than- or-equal-to 0.48%, suggesting that A. americanum may be a vector of hu man ehrlichiosis.