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Title: Influence of orientia tsutsugamushi infection on the developmental biology of leptotrombidium imphalum and leptotrombidium chiangraiensis (Acari: Trombiculidae)

Author
item PHASOMKUSOLSIL, SIRIPORN - Us Army Medical Center
item TANSKUL, PANITA - Us Army Medical Center
item RATANATHAM, SUPAPORN - Mahidol University
item WATCHARAPICHAT, POCHAMAN - Royal Thai Army
item PHULSUKSOMBATI, DUANGPORN - Royal Thai Army
item FRANCES, STEPHEN - Us Army Medical Center
item LERDTHUSNEE, KRIANGKRAI - Us Army Medical Center
item Linthicum, Kenneth - Ken

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/13/2009
Publication Date: 11/1/2012
Citation: Phasomkusolsil, S., Tanskul, P., Ratanatham, S., Watcharapichat, P., Phulsuksombati, D., Frances, S.P., Lerdthusnee, K., Linthicum, K. 2012. Influence of orientia tsutsugamushi infection on the developmental biology of leptotrombidium imphalum and leptotrombidium chiangraiensis (Acari: Trombiculidae). Journal of Medical Entomology. 49(6):1270-1275. DOI: 10.1603/ME12100.

Interpretive Summary: The immature stages of blood feeding mites, called chiggers, transmit an important human disease called scrub typhus in much of Asia. Orientia tsutsugamushi is the disease causing agent of scrub typhus and it is related to other rickettsial organisms that cause human diseases like Rocky Mountain Spotted fever and Louse-borne typhus . We documented that the disease causing agent is passed through various stages of the mite and is efficiently passed on to subsequent generations of mites and the chigger stage of mite can readily transmit the disease to animals and humans. Transmission was more efficient in Leptotrombidium chiangraiensis mites than in Leptotrombidium imphalum mites.

Technical Abstract: Transovarial transmission of Orientia tsutsugamushi (Hayashi) in laboratory colonies of Leptotrombidium chiangraiensis (Tanskul & Linthicum) and Leptotrombidium imphalum (Vercammen-Grandjean & Langston) was studied for two generations. In L. chiangraiensis the transovarial and filial infection rate was 100% in each generation. Only infected females were produced. In L. imphalum, the transovarial infection rate of the parental generation was 100% but declined to 93.3% in the F1. The overall filial infection rate was 100% in the F1 but was only 62.3% in the F2. In infected lines, only infected females were produced in the F1, but 1.5% of the F2 progeny were infected males. Lower rates of transovarial transmission in L. imphalum may be the cause of the lower natural infection rates found in nature.