Rickettsia amblyommii Infecting Amblyomma americanum Larvae
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...
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Veröffentlicht in: | Vector borne and zoonotic diseases (Larchmont, N.Y.) N.Y.), 2008-02, Vol.8 (1), p.15-24 |
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Zusammenfassung: | 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. |
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ISSN: | 1530-3667 1557-7759 |
DOI: | 10.1089/vbz.2007.0138 |