Stromdahl EY, Vince MA, Billingsley PM, Dobbs NA, Williamson PC. Entomological Sciences Program, U.S. Army Center for Health Promotion and Preventive Medicine, Aberdeen Proving Ground, Maryland.
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.
PMID: 18171102
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Detection of "Rickettsia amblyommii" in Association with a Tick Bite Rash.
Billeter SA, Blanton HL, Little SE, Levy MG, Breitschwerdt EB. Vector-Borne Diagnostic Disease Laboratory, North Carolina State University, College of Veterinary Medicine, Raleigh, North Carolina.
In the summer of 2006, an Amblyomma americanum tick was removed from a woman in central North Carolina, who subsequently developed a rash at the site of tick attachment. When examined by polymerase chain reaction (PCR) for Borrelia, Anaplasma, Ehrlichia, Babesia, Rickettsia, and Bartonella DNA, only the Rickettsia primers generated an amplicon, which was identified as "R. amblyommii" by sequencing.
To our knowledge, this is the first case in which R. amblyommii was temporally associated with a rash.
PMID: 18052716
-------------------- There is no wealth but life. -John Ruskin
All truth goes through 3 stages: first it is ridiculed: then it is violently opposed: finally it is accepted as self evident. - Schopenhauer Posts: 5639 | From Aptos CA USA | Registered: Apr 2005
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posted
1: Arch Intern Med. 1997 Dec 8-22;157(22):2635-41.Links Comment in: Arch Intern Med. 1998 Oct 26;158(19):2162-5.
Erythema migrans-like rash illness at a camp in North Carolina: a new tick-borne disease?
Kirkland KB, Klimko TB, Meriwether RA, Schriefer M, Levin M, Levine J, Mac Kenzie WR, Dennis DT. Epidemic Intelligence Service, and Division of Field Epidemiology, Centers for Disease Control and Prevention, Atlanta, GA, USA.
BACKGROUND: Borrelia burgdorferi, the causative agent of Lyme disease, has never been isolated from a patient thought to have acquired Lyme disease in any southeastern state. OBJECTIVE: To investigate 14 cases of an erythema migrans (EM)-like rash illness that occurred during 2 summers at an outdoor camp in central North Carolina in an effort to determine the etiologic, epidemiological, and clinical aspects of this illness.
METHODS: Using active surveillance, we identified cases of clinically diagnosed EM in residents and staff of the camp. We collected clinical and demographic information; history of exposure to ticks; acute and convalescent serum antibodies to B. burgdorferi, Rickettsia rickettsii, and Ehrlichia chaffeensis; and cultures for spirochetes from biopsy specimens of skin lesions. Serum samples from a group of residents and staff who did not develop rashes were tested for the same antibodies. We speciated ticks removed from people and collected from vegetation.
RESULTS: We identified 14 cases of EM-like rash illness during the 2 summers. Of the 14 case-patients, 10 had associated mild systemic symptoms and 1 had documented fever. All 14 case-patients had removed attached ticks, and 8 remembered having removed a tick from the site where the rash developed a median of 12 days earlier (range, 2-21 days). One tick removed from the site where a rash later developed was identified as Amblyomma americanum, the Lone Star tick; 97% of ticks collected from vegetation and 95% of ticks removed from people were A. americanum. No spirochetes were isolated from skin biopsy specimens. Paired serum samples from 13 case-patients did not show diagnostic antibody responses to B. burgdorferi or other tick-borne pathogens.
CONCLUSIONS: This investigation suggests the existence of a new tick-associated rash illness. We suspect that the disease agent is carried by A. americanum ticks. In the southern United States, EM-like rash illness should no longer be considered definitive evidence of early Lyme disease.
PMID: 9531233
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In the second abstract, it is not clear whether they are testing the tick or the woman. If the latter, not sure that a negative pcr is absolute proof that these other pathogens were not there also.
They might be trying to discredit the EM as diagnostic of lyme. But what does it matter whether multiple pathogens can cause a rash.....they still need to be treated.
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