Seroprevalence of antibodies against spotted fever group rickettsia among dogs and humans in Okinawa, Japan

Japanese Spotted Fever and Irreversible Renal Dysfunction during Immunosuppressive Therapy after a Living-Donor Kidney Transplant

Ten years ago, a 56-year-old woman with a history of IgA nephropathy who received a living-donor kidney transplant across ABO barriers was managed with immunosuppressive drugs. The kidney transplant donor was her father who had poor kidney function. The patient’s renal function was stable for 10 years. The patient visited our department with a complaint of skin rash, occurring 2 days after an onset of fever. Although a skin rash is atypical for Japanese spotted fever (JSF), we suspected JSF and started treatment with minocycline because we found a scar suggestive of an eschar. Furthermore, the blood test results were similar to those associated with JSF, and the patient lived in a JSF-endemic area. The patient’s symptoms improved after 1 week. She was diagnosed with JSF by serological tests against Rickettsia japonica. JSF usually does not cause any complications after recovery. However, the patient’s renal function did not completely recover. JSF can cause an atypical rash in patients taking excessive immunosuppressive drugs. Early treatment is required for patients with suspected JSF to prevent complications of renal dysfunction after receiving a living-donor kidney transplant.

Seroepidemiological Study of Spotted Fever Group Rickettsiae and Identification of a Putative New Species, Rickesttsia 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 (Rhipicephalus sanguineus, Rhipicephalus haemaphysaloides, Dermacentor auratus, Haemaphysalis hystricis, Haemaphysalis ornithophila) were collected. Rickettsia spp. were detected in 6.5% (12/184) of ticks. Rickettsia sp. TwKM01 was found in 6 R. sanguineus and 4 R. haemaphysaloides; while Rickettsia sp. TwKM03 was identified in 1 R. sanguineus. Moreover, gene-based pairwise analysis indicated identification of a putative new species, Rickettsia sp. Da-1, in D. auratus. These findings provided evidence of SFG rickettsiae infection in ticks and suggested SFG rickettsiae exposure in the residents.

Distribution and Ecological Drivers of Spotted Fever Group Rickettsia in Asia

Spotted fever group and related rickettsia (SFGR) are a neglected group of pathogens that belong to the genus Rickettsia. SFGR are zoonotic and are transmitted by arthropod vectors, primarily ticks, fleas and mites to accidental hosts. These emerging and re-emerging infections are widely distributed throughout the world. Land-use change and increasing human-wildlife conflict compound the risk of SFGR infection to local people in endemic areas and travelers to these regions. In this article, we discuss the rickettsial organisms causing spotted fever and related diseases, their arthropod vectors in Asia and the impact of land-use change on their spread.

Improvement in early diagnosis of Japanese spotted fever by using a novel Rick PCR system

Rickettsia diseases, including Japanese spotted fever (JSF), are serious infections. Delayed diagnosis occasionally results in life-threatening liver disorders and disseminated intravascular coagulation (DIC). Because of the shortness of the latent period, serological diagnosis is not preferable for early diagnosis of JSF. Until now, a polymerase chain reaction (PCR)-based diagnosis method has been used for early diagnosis, and the sensitivity reaches as high as 90% using skin biopsy samples as we previously reported. On the other hand, the sensitivity of the same PCR method using blood samples is limited at less than 50%. In the present study, using peripheral blood samples, we developed a novel diagnostic method for JSF using a Rick PCR system with original PCR primers, showing improved sensitivity compared with the conventional nested PCR. It may constitute a preferable diagnostic tool for early and sensitive diagnosis of Rickettsia infection.

Characterization of spotted fever group rickettsiae detected in dogs and ticks in Okinawa, Japan

Spotted fever group (SFG) rickettsial DNAs were detected in 2.4% of 340 canine blood samples and a pool of 84 tick pool samples (229 ticks) collected in Okinawa, Japan by PCR using a citrate synthase and an SFG rickettsial 190-kDa surface antigen gene primer pair. The sequences of both genes from canine blood and tick samples showed high levels of similarity with those of Rickettsiajaponica and several SFG rickettsiae (R. aeschlimannii, R. massiliae, R. rhipicephali and Bar-29 strain). Phylogenesis of canine blood and tick samples was closely related to that of reference SFG rickettsiae. Serological evidence of SFG rickettsial infection in dogs and humans in Okinawa, where no clinical human cases have been reported, has been obtained. In this study, genetical characterization of SFG rickettsia in Okinawa was investigated phylogenetically.

Survey of tick infestation and tick-borne ehrlichial infection of dogs in Ishigaki Island, Japan

Twelve (54.5%) of 22 free-roaming dogs in Ishigaki Island had tick infestation identified as Rhipicephalus sanguineus. There were 121 ticks recovered and consisted of 28 females, 58 males, 22 nymphs and 3 larvae. Infection of dogs possibly with canine ehrlichial pathogens was examined by both indirect immunofluorescence assay and polymerase chain reaction (PCR). Two dogs of the 13 examined were sero-positive for the human granulocytic ehrlichia agent, and one of two dogs was PCR positive for Ehrlichia platys. This dog had platelet numbers slightly lower than normal value, however, no morulae were found within platelet on peripheral blood smear stained with Giemsa.