Seroepidemiological Study of Spotted Fever Group Rickettsiae and Identification of a Putative New Species, sp. Da-1, in Gongliao, Northeast Taiwan.

Tick-borne spotted fever group (SFG) rickettsioses were neglected in Taiwan. The study reported a seroepidemiological survey of SFG rickettsiae in residents in Gongliao District, Northeast Taiwan. Blood samples were examined for antibodies against SFG rickettsiae by enzyme-linked immunosorbent assay and immunofluorescence assay. Risk factors were assessed using logistic regression. Ticks parasitizing dogs were collected within a 2 km radius from the houses of seropositive participants, and PCR was performed to detect possible tick-borne pathogens. Of 1108 participants, 75 (6.8%) had antibodies against SFG rickettsiae. Residents were more likely to be seropositive if they were older than 65 years, recruited by Dr. Enjoy's Clinic, or resided in Jilin village. A total of 184 ticks including 5 species (, , , , ) were collected. spp. were detected in 6.5% (12/184) of ticks. sp. TwKM01 was found in 6 and 4 ; while sp. TwKM03 was identified in 1 . Moreover, gene-based pairwise analysis indicated identification of a putative new species, sp. Da-1, in . These findings provided evidence of SFG rickettsiae infection in ticks and suggested SFG rickettsiae exposure in the residents.