OBJECTIVETo identify genotype of eight strains of Orientia tsutsugamushi (O. tsutsugamushi) isolated from Nan Peng Lie Islands in China and establish tsutsugamushi disease nature foci for this region.

METHODSThe nested polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) were used. Three primers were selected from the DNA sequence of the gene encoding type-specific 56-kDa protein of the Karp strain. The positive products were digested by Hine II and Pst I, meanwhile profiles specific to each strain were analyzed.

RESULTSThree genotypes of O. tsutsugamushi including Karp, Kato and a new strain existed on Nan Peng Lie Islands.

CONCLUSIONNan Peng Lie Islands is tsutsugamushi disease nature foci.

Animals ; China ; DNA, Bacterial ; analysis ; Genotype ; Mice ; Orientia tsutsugamushi ; genetics ; Polymorphism, Restriction Fragment Length ; Rats

OBJECTIVETo investigate natural foci of tsutsugamushi disease whose incidence has increased in the Nan Peng Lie Islands in China, an area where this disease has not been previously recorded.

METHODSWe recorded the natural foci and isolated Orientia tsutsugamushi (O. tsutsugamushi) organism. We also studied prevention measures.

RESULTSThese islands had the natural foci of a south subtropical zone. The main host and vector were Rattus norvegicus and Leptotrombidium deliens (L. deliens), respectively. The seasonal quantity trends of Rattus norvegicus and Leptotrombidium deliens were consistent with the incidence of human infection. Thirty-five strains of O. tsutsugamushi were isolated from Rattus norvegicus and L. deliense. The identification of 7 strains showed that most strains were Karp. Seroepidemiology showed a high prevalence of antibody against O. tsatsugamushi among local people. After prevention measures were used, the incidence was decreased.

CONCLUSIONThis was the first successful confirmation that the Nan Peng Lie Islands were natural foci of tsutsugamushi disease.

Animals ; Antibodies, Bacterial ; blood ; Cattle ; China ; epidemiology ; DNA, Bacterial ; genetics ; Geography ; Humans ; Incidence ; Orientia tsutsugamushi ; genetics ; growth & development ; isolation & purification ; Polymorphism, Restriction Fragment Length ; Rats ; Scrub Typhus ; epidemiology ; microbiology ; Seasons ; Sheep ; Species Specificity ; Tropical Climate