a new species of leptotrombidium (acari:trombiculidae) collected in active rice fields in northern thailand.leptotrombidium (leptotrombidium) chiangraiensis tanskul & linthicum is described and illustrated as new from specimens collected from the rodents rattus rattus (l., 1758), rattus argentiventer (robinson & kloss, 1916), rattus losea (swinhoe, 1870), and bandicota indica (bechstein, 1800) in chiangrai province northern thailand. the new species was collected in active rice fields and adjacent fruit plantation areas. the etiological agent of scrub typhus, orientia (formerly rickettsia) tsutsugamus ...19979151504
a new ecology for scrub typhus associated with a focus of antibiotic resistance in rice farmers in thailand.following the documentation of chloramphenicol-resistant and doxycycline-resistant strains of orientia tsutsugamushi (hyashi) in northern thailand, we conducted ecological and epidemiological studies near the houses of patients hospitalized with antibiotic-resistant infections. new associations between chiggers, rodents, and o. tsutsugamushi in active rice agriculture areas, an ecological habitat not described previously, are reported. rattus rattus (l.) was the most common species (representing ...19989701943
scrub typhus: vector competence of leptotrombidium chiangraiensis chiggers and transmission efficacy and isolation of orientia tsutsugamushi.a total of 4,281 rodents, belonging to 20 species, was collected from three villages in chiangrai province, northern thailand, from january 1994 to december 2001. the predominant species were rattus rattus, r. losea and bandicota indica, accounting for 96% of the total. more than 135,000 chigger mites were removed from wild rodents of which 1% were identified as leptotrombidium chiangraiensis, a new species vector of scrub typhus. five orientia tsutsugamushi-infected l. chiangraiensis colonies e ...200312860596
transstadial and transovarial transmission of orientia tsutsugamushi in leptotrombidium imphalum and leptotrombidium chiangraiensis (acari: trombiculidae).transovarial transmission of orientia tsutsugamushi (hayashi) in laboratory colonies of leptotrombidium chiangraiensis tanskul & linthicum and leptotrombidium imphalum (vercammen-grandjean & langston) (acari: trombiculidae) 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 ...200919960694
influence of orientia tsutsugamushi infection on the developmental biology of leptotrombidium imphalum and leptotrombidium chiangraiensis (acari: trombiculidae).leptotrombidium chiangraiensis tanskul & linthicum, and leptotrombidium imphalum vercammen-grandjean are important vectors of scrub typhus in rice field habitats in northern thailand. the developmental biology of all stages of the life cycle of two generations of these species of mites infected with orientia tsutsugamushi (hayashi) and uninfected mites is reported. the development of the infected lines of both f1 and f2 l. chiangraiensis were significantly longer than their respective uninfected ...201223270154
development of an orientia tsutsugamushi lc-1 murine intraperitoneal challenge model for scrub typhus: determination of murine lethal dose (muld50), tissue bacterial loads, and clinical outcomes.currently, no vaccine has been developed to protect humans from naturally acquired heterologous orientia tsutsugamushi infections. to enhance the validity of vaccine candidates, we are developing a murine chigger challenge model with the o. tsutsugamushi lc-1-infected leptotrombidium chiangraiensis line-1. to this end, an intraperitoneal (i.p.) murine challenge model using an o. tsutsugamushi lc-1 isolate was developed for eventual validation of the chigger challenge model. we have determined th ...201526378973
establishment of orientia tsutsugamushi lc-1 (rickettsiales: rickettsiaceae) infection in icr outbred mice (rodentia: muridae) by needle challenge.orientia tsutsugamushi is a pathogen transmitted by leptotrombidium that causes scrub typhus. to develop an infection mouse model, a mite-derived isolate of o. tsutsugamushi was established from a laboratory-maintained colony of leptotrombidium chiangraiensis (o. tsutsugamushi lc-1). this lc-1 isolate was initially presented to icr (cd-1) mice by feeding an infected lc chigger on the ear of a mouse. once the lc-1 was adapted to the icr mice, quantitative real-time polymerase chain reaction was u ...201424897859
characterization based on the 56-kda type-specific antigen gene of orientia tsutsugamushi genotypes isolated from leptotrombidium mites and the rodent host post-infection.abstract. characterization of the 56-kda type-specific antigen (tsa) genes of orientia tsutsugamushi (ot) from three naturally infected, laboratory-reared mite colonies comprising three species (leptotrombidium deliense [ld], leptotrombidium imphalum [li], and leptotrombidium chiangraiensis [lc]) has revealed the presence of single and coexisting ot genotypes found in individual chiggers. the karp genotype was found in all of the chiggers examined, whereas gilliam and ut302 genotypes were only o ...201424297814
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