Orientia tsutsugamushi isolated from patients with suspected tsutsugamushi disease, chigger mites and mice with scrub typhus in Fuyang and genotypes

OBJECTIVE To identify the Orientia tsutsugamushi strains isolated from whole blood specimens of patients, chigger mites and liver and spleen specimens of field mice so as to provide evidence for further confirming that Fuyang is a new epidemic foci.METHODS From September to November in 2009-2010, the specimens were collected from anticoagulants of patients with suspected tsutsugamushi disease, wild mice and chigger mites, the O.tsutsugamushi strains were isolated by using mouse passaged separation method, and the genes were sequenced with the use of nested-PCR.RESULTS The nucleic acid test showed positive for part of the liver and spleen tissues of the mice as the fresh blood or anticoagulants specimens passed to third-fourth generation whole blood PCR positive group 59, 15 strains were positive after the separation of the mice; the chigger mite 20 group, three of which were PCR positive, and 1 strain was positive after the separation of the mice; of the 256 wild mice, 7 were PCR positive, the mice were separated to 35 groups, and 1 strain showed positive. The amplified products were sequenced, and the sequencing analysis showed that O.tsutsugamushi belonged to Kawasaki genotype.CONCLUSION The pathogen that is initially isolated from the autumn-winter tsutsugamushi epidemic seasonal patients, wild-type rodent Apodemus agrarius and small shield fiber mite body is the O.tsutsugamushi, and Fuyang is etiologically confirmed as the new epidemic foci.