Infection Rates of Amblyomma Americanum and Dermacentor Variablis by Francisella Tularensis and Borrelia Lonestari in Southwest Missouri
Francisella tularensis and Borrelia lonestari are the bacteria that cause tularemia and erythema migrans-like rash, respectively. F. tularensis is capable of being transmitted to humans through the bite of an infected Amblyomma americanum tick or Dermacentor variabilis tick, while the primary vector of B. lonestari appears to be only A. americanum. The purpose of this study was to determine the overall infection rates of these two bacterial pathogens and to better establish the risks associated with tick attachment to humans. Adult and nymphal A. americanum and D. variabilis ticks were collected in June of 2009 and 2010. DNA was extracted from the ticks and used in nested PCR assays to identify F. tularensis using the fopA gene and B. lonestari using the flab gene. F. tularensis was present in 5.3% of adult A. americanum ticks (21/394) and 8.9% of adult D. variabilis ticks (17/192). A minimum infection rate of nymph pools was 0.7% for F. tularensis (4/560). An infection rate of 3.0% (12/394) for B. lonestari was observed in adult A. americanum ticks. Subsequent DNA sequencing of both Francisella and Borrelia PCR products was used to confirm the presence of suspected pathogen genes.
Amblyomma, Dermacentor, tularensis, Borrelia, STARI, epidemiology, Biology
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