Bacterial Pathogens in Ixodid Ticks from a Piedmont County in North Carolina: Prevalence of Rickettsial Organisms

Abstract

In North Carolina, reported human cases of tick-borne illness, specifically Rocky Mountain spotted fever, have escalated over the past decade. To determine the relative abundance of vectors and to estimate the risk of acquiring a tick-borne illness in peri-residential landscapes, ticks were collected in Chatham County, a typical Piedmont county and, samples of the ticks were tested for infection with selected bacterial pathogens using realtime quantitative polymerase chain reaction assays. Ticks (n = 3746) were collected by flagging vegetation at 26 sites from April to July 2006. The predominant questing tick was Amblyomma americanum (98.5%) with significantly fewer Dermacentor variabilis (1.0%) and Ixodes scapularis (O.SO/o) collected. Spotted fever group (SFG) rickettsiae were detected in 68.2% of 1590 A. americanum with 56.4% of the molecular isolates identified as Rickettsia amblyommii, an informally named member of the SFG rickettsiae. Comparatively, smaller numbers of A. americanum contained Ehrlichia chaffeensis (1.8%) and Borrelia lonestari (0.4%). Of 15 I. scapularis nymphs tested 6 (40%) were positive for Borrelia burgdorferi sensu lato. Seven (19.4%) of 36 adult D. variabilis tested positive for Rickettsia montanensis, 4 (11.1%) were positive for R. amblyommii, and 5 (13.9%) were infected with unidentified species of SFG rickettsiae. The tick population in Chatham County contains a diverse array of microbes, some of which are known or potential pathogens. Highest attack rates would be expected from A. americanum ticks, and highest potential risk of infection with a tick-transmitted agent would be to rickettsial organisms, particularly R. amblyommii. Accordingly, longitudinal eco-epidemiology investigations are needed to determine the public health importance of A. americanum infected with rickettsial organisms.

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Document Details

Document Type
Technical Report
Publication Date
Jan 01, 2010
Accession Number
ADA552984

Entities

People

  • Allen L Richards
  • Charles S. Apperson
  • Ju Jiang
  • Loganathan Ponnusamy
  • Luma Abu Ayyash
  • Michael P. Smith

Organizations

  • Naval Medical Research Center

Tags

DTIC Thesaurus Topics

  • Alphaproteobacteria
  • Arachnid Bites And Stings
  • Bacteria
  • Cervidae
  • Chain Reactions
  • Chemical Reactions
  • Habitats
  • Lyme Disease
  • Medical Personnel
  • North Carolina
  • Polymerase Chain Reaction
  • Public Health
  • Rocky Mountains
  • Tickborne Diseases
  • Ticks
  • United States
  • Viruses

Readers

  • Aquatic Ecology
  • Infectious Disease/Epidemiology
  • Vector-Borne Disease and Entomology