title: Comparison of phenology and pathogen prevalence, including infection with the Ehrlichia muris-like (EML) agent, of Ixodes scapularis removed from soldiers in the midwestern and the northeastern United States over a 15 year period (1997-2012).
abstract: BACKGROUND
  Since 1997, human-biting ticks submitted to the Department of Defense Human Tick Test Kit Program (HTTKP) of the US Army Public Health Command have been tested for pathogens by PCR. We noted differences in the phenology and infection prevalence among Ixodes scapularis ticks submitted from military installations in different geographic regions. The aim of this study was to characterize these observed differences, comparing the phenology and pathogen infection rates of I. scapularis submitted from soldiers at two sites in the upper Midwest (Camp Ripley, MN, and Ft. McCoy, WI) and one site in the northeastern US (Ft. Indiantown Gap, PA).
  
  
  METHODS
  From 1997 through 2012, the HTTKP received 1,981 I. scapularis from the three installations and tested them for Anaplasma phagocytophilum, Babesia microti, Borrelia burgdorferi and the Ehrlichia muris-like (EML) agent using PCR; pathogen presence was confirmed via sequencing or amplification of a second gene target. Pathogen and co-infection prevalence, tick engorgement status, and phenology were compared among installations.
  
  
  RESULTS
  Greater rates of A. phagocytophilum and Ba. microti infections were detected in ticks submitted from installations in Minnesota than in Wisconsin or Pennsylvania, and the EML agent was only detected in ticks from Minnesota and Wisconsin. Midwestern ticks were also more likely to be co-infected than those from Pennsylvania. Both adult and nymphal ticks showed evidence of feeding on people, although nymphs were more often submitted engorged. Adult I. scapularis were received more frequently in June from Minnesota than from either of the other sites. Minnesota adult and nymphal peaks overlapped in June, and submissions of adults exceeded nymphs in that month.
  
  
  CONCLUSIONS
  There were clear differences in I. scapularis phenology, pathogen prevalence and rates of co-infection among the three military installations. Seasonal and temperature differences between the three sites and length of time a population had been established in each region may contribute to the observed differences. The synchrony of adults and nymphs observed in the upper Midwest has implications for pathogen infection prevalence. The EML agent was only detected in Minnesota and Wisconsin, supporting the previous assertion that this pathogen is currently limited to the upper Midwest.
authors.affiliation: U.S. Army Public Health Command, Aberdeen Proving Ground, MD, USA. ellen.y.stromdahl.civ@mail.mil.
authors.forename: Ellen
authors.initials: E
authors.lastname: Stromdahl
authors.affiliation: Texas A&M University, College Station, TX, USA. shamer@cvm.tamu.edu.
authors.forename: Sarah
authors.initials: S
authors.lastname: Hamer
authors.affiliation: Mayo Clinic, Rochester, MN, USA. Jenkins.sarah@mayo.edu.
authors.forename: Sarah
authors.initials: S
authors.lastname: Jenkins
authors.affiliation: Mayo Clinic, Rochester, MN, USA. Sloane.lynne@mayo.edu.
authors.forename: Lynne
authors.initials: L
authors.lastname: Sloan
authors.affiliation: University of North Texas Health Science Center, Ft. Worth, TX, USA. pwilliamson@mycts.org.|Creative Testing Solutions, Tempe, AZ, USA. pwilliamson@mycts.org.
authors.forename: Phillip
authors.initials: P
authors.lastname: Williamson
authors.affiliation: U.S. Army Public Health Command, Aberdeen Proving Ground, MD, USA. erik.s.foster.mil@mail.mil.|Michigan Department of Community Health, Lansing, MI, USA. erik.s.foster.mil@mail.mil.
authors.forename: Erik
authors.initials: E
authors.lastname: Foster
authors.affiliation: U.S. Army Public Health Command, Aberdeen Proving Ground, MD, USA. robyn.m.nadolny.ctr@mail.mil.|Department of Biological Sciences, Old Dominion University, Norfolk, VA, USA. robyn.m.nadolny.ctr@mail.mil.
authors.forename: Robyn
authors.initials: R
authors.lastname: Nadolny
authors.affiliation: U.S. Army Public Health Command, Aberdeen Proving Ground, MD, USA. chad.e.elkins3.ctr@mail.mil.
authors.forename: Chad
authors.initials: C
authors.lastname: Elkins
authors.affiliation: U.S. Army Public Health Command, Aberdeen Proving Ground, MD, USA. mary.a.vince.civ@mail.mil.
authors.forename: Mary
authors.initials: M
authors.lastname: Vince
authors.affiliation: Mayo Clinic, Rochester, MN, USA. pritt.bobbi@mayo.edu.
authors.forename: Bobbi
authors.initials: B
authors.lastname: Pritt
mesh_terms: D000710:Anaplasmataceae / Q000302:isolation & purification*; D000818:Animals; D041001:Babesia microti / Q000302:isolation & purification*; D025065:Borrelia burgdorferi / Q000302:isolation & purification*; D005260:Female; D006801:Humans; D018884:Ixodes / Q000254:growth & development / Q000382:microbiology* / Q000469:parasitology*; D015146:Midwestern United States / Q000453:epidemiology; D008889:Military Personnel; D009511:New England / Q000453:epidemiology; D016133:Polymerase Chain Reaction; D015995:Prevalence; D012621:Seasons; D017422:Sequence Analysis, DNA; D013696:Temperature; D013984:Tick Infestations / Q000453:epidemiology*