Topic: US Army Researcher Speaking on Tick Borne Disease- MD/PA
Tincup
Honored Contributor (10K+ posts)
Member # 5829
posted
To raise awareness...
The Harford County Lyme Disease Support Group, Inc. invited Ellen Stromdahl, an Entomologist with the U. S. Army Center for Health Promotion and Preventive Medicine at Aberdeen Proving Ground to present a program on ticks and tick borne diseases.
She is a highly-regarded, published researcher with an expertise in tick borne diseases.
The program will be offered free of charge as part of the May is Lyme Disease Awareness Month campaign.
It will be at the Highland Presbyterian Church, 701 Highland Road, in Street, MD on Thursday, May 14, 2009 at 7:00 PM.
Infectious Disease Pathology Branch, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
Geographic distribution of Rickettsia parkeri in its US tick vector, Amblyomma maculatum, was evaluated by PCR.
R. parkeri was detected in ticks from Florida, Georgia, Kentucky, Mississippi, Oklahoma, and South Carolina, which suggests that A. maculatum may be responsible for additional cases of R. parkeri rickettsiosis throughout much of its US range.
We used a nested PCR with Borrelia flagellin gene (flaB) primers and DNA sequencing to determine if Borrelia lonestari was present in Amblyomma americanum ticks removed from military personnel and sent to the Tick-Borne Disease Laboratory of the U.S. Army Center for Health Promotion and Preventive Medicine.
In our preliminary investigation, we detected Borrelia sequences in 19 of 510 A. americanum adults and nymphs from Ft. A. P. Hill, Va.
During the 2001 tick season, the flaB primers were used to test all A. americanum samples as they were received, and 29 of 2,358 A. americanum samples tested individually or in small pools were positive.
PCRs with 2,146 A. americanum samples in 2002 yielded 26 more Borrelia-positive samples.
The positive ticks in 2001 and 2002 were from Arkansas, Delaware, Kansas, Kentucky, Maryland, New Jersey, North Carolina, Tennessee, and Virginia.
The last positive sample of the 2001 season was a pool of larvae.
To further investigate larval infection, we collected and tested questing A. americanum larvae from Aberdeen Proving Ground, Md.; 4 of 33 pools (40 larvae per pool) were positive.
Infection of unfed larvae provides evidence of the maintenance of B. lonestari by means of transovarial transmission.
Sequence analysis revealed that the amplicons were identical to sequences of the B. lonestari flaB gene in GenBank.
Despite the low prevalence of infection, the risk of B. lonestari transmission may be magnified because A. americanum is often abundant and aggressive, and many tick bite victims receive multiple bites.
Entomological Sciences Program, US Army Center for Health Promotion and Preventive Medicine, Aberdeen Proving Ground, MD 21010-5403, USA.
Polymerase chain reaction analysis of Amblyomma americanum adults, nymphs, and larvae from Aberdeen Proving Ground, MD (APG), revealed a very high prevalence of a spotted fever group (SFG) rickettsia.
Restriction fragment length polymorphism (RFLP) and sequence analysis identified "Rickettsia amblyommii."
This organism is not yet described or well studied, and its pathogenicity is unknown; however, investigations of the organism are warranted because of its high prevalence in A. americanum.
This tick is extremely abundant at military training facilities in the south, central, and Mid-Atlantic United States, and many soldiers experience multiple concurrent tick bites.
Bites by R. amblyommii-infected A. americanum may account for rates of SFG rickettsia seropositivity that are higher than reported rates of Rocky Mountain spotted fever (RMSF) cases from the same location.
Seroconversion to SFG rickettsia following bites of A. americanum may suggest that R. amblyommii is infectious in humans.
Subclinical infection in the numerous A. americanum tick bite victims could contaminate donated blood and compromise immunodeficient recipients.
Detection of R. amblyommii in questing A. americanum larvae suggests transovarial transmission.
The absence of R. rickettsii, the agent of RMSF, in A. americanum may be due to transovarial interference by R. amblyommii.
The likelihood of pathogen transmission by larvae is magnified by their habit of mass attack.
The very small size of the larvae is also a risk factor for pathogen transmission.
High R. amblyommii prevalence in populations of A. americanum presage co-infection with other A. americanum-borne pathogens.
A. americanum nymphs and adults from APG were found to be co-infected with R. amblyommii and Borrelia lonestari, Ehrlichia chaffeensis and Ehrlichia ewingii, respectively, and larval pools were infected with both R. amblyommii and B. lonestari.
Co-infections can compound effects and complicate diagnosis of tick-borne disease.
`````````````````````````````````````````````````
BMC Infect Dis. 2008 Apr 23;8:54. Links
Geographic distribution and genetic diversity of the Ehrlichia sp. from Panola Mountain in Amblyomma americanum.
Loftis AD, Mixson TR, Stromdahl EY, Yabsley MJ, Garrison LE, Williamson PC, Fitak RR, Fuerst PA, Kelly DJ, Blount KW. Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
BACKGROUND: A novel Ehrlichia, closely related to Ehrlichia ruminantium, was recently discovered from Panola Mountain State Park, GA, USA.
We conducted a study to determine if this agent was recently introduced into the United States.
METHODS: We developed a sensitive PCR assay based on the conserved gltA (citrate synthase) gene and tested DNA samples extracted from 1964 field-collected and 1835 human-biting Amblyomma americanum from 23 eastern states of the USA.
RESULTS: The novel agent was detected in 36 ticks collected from 10 states between 1998 and 2006.
Infected ticks were collected both from vegetation (n = 14, 0.7%) and from humans (n = 22, 1.2%).
Fragments of the conserved gltA gene and the variable map1 gene were sequenced from positive samples.
Two distinct clades, with 10.5% nucleic acid divergence over the 730 bp map1 sequence, were identified.
CONCLUSION: These data suggest that the Panola Mountain Ehrlichia was not recently introduced to the United States; this agent has an extensive distribution throughout the range of its tick vector, has been present in some locations for several years, and displays genetic variability.
Furthermore, people in several states were exposed to this agent through the bite of infected ticks, underscoring the potential public health risk of this emerging ehrlichiosis.
The Lyme Disease Network is a non-profit organization funded by individual donations. If you would like to support the Network and the LymeNet system of Web services, please send your donations to:
The
Lyme Disease Network of New Jersey 907 Pebble Creek Court,
Pennington,
NJ08534USA http://www.lymenet.org/
UBBFriend: Email this page to someone!
![[Big Grin]](biggrin.gif)
![[Smile]](smile.gif)
hugs
Printer-friendly view of this topic