Molecular investigation of tick-borne pathogens in ticks removed from tick-bitten humans in the southwestern region of the Republic of Korea.

In this study, we investigated the presence of tick-borne pathogens in ticks removed from tick-bitten humans in the southwestern provinces of the Republic of Korea (ROK). We identified 33 ticks from three tick species, namely Amblyomma testudinarium (60.6%), Haemaphysalis longicornis (27.3%), and Ixodes nipponensis (12.1%) in order of occurrence via morphology and 16S rDNA-targeting polymerase chain reaction (PCR). Tick-borne pathogens were detected in 16 ticks using pathogen-specific PCR. From the results, 12 ticks (36.4%) tested positive for spotted fever group (SFG) Rickettsia: Rickettsia monacensis (1/12), R. tamurae (8/12), and Candidatus Rickettsia jingxinensis (3/12). Three ticks (9.1%) were positive for Anaplasma phagocytophilum. In addition, three ticks (9.1%) tested positive for Babesia gibsoni (1/3) and B. microti (2/3). In conclusion, we identified three tick species; the most common species was A. testudinarium, followed by H. longicornis and I. nipponensis. SFG Rickettsia, A. phagocytophilum, and Babesia spp. were the most frequently detected pathogens in ticks removed from tick-bitten humans. To our knowledge, this is the first report of R. tamurae and Ca. R. jingxinensis detection in Korea. The present results will contribute to the understanding of tick-borne infections in animals and humans in the ROK.

A case of SFTS coinfected with E. coli bacteremia.

BACKGROUND: Severe fever thrombocytopenia syndrome virus (SFTSV) is the causative agent of severe fever thrombocytopenia syndrome (SFTS). SFTS is an emerging infectious disease, characterized by high fever, gastrointestinal symptoms, leukopenia, thrombocytopenia, and a high mortality rate. Until now, little importance has been given to the association of SFTS with leukocytosis and bacterial co-infection. CASE PRESENTATION: A 51-year old man visited our hospital with fever and low blood pressure. He was a farmer by occupation and often worked outdoors. He had a Foley catheter inserted due to severe BPH. Laboratory tests revealed thrombocytopenia, elevated liver function, and elevated CRP levels. He had marked leukocytosis, proteinuria, hematuria, and conjunctival hemorrhage. Initially, we thought that the patient was suffering from hemorrhagic fever with renal syndrome (HFRS). However, we confirmed SFTS through PCR and increasing antibody titer. However, his blood culture also indicated E. coli infection. CONCLUSION: SFTS displays characteristics of fever, thrombocytopenia, elevated liver function, and leukocytopenia. We described a case of SFTS with leukocytosis due to coinfection with E. coli. Since patients with SFTS usually have leukocytopenia, SFTS patients with leukocytosis are necessarily evaluated for other causes of leukocytosis. Here, we report the first case of an SFTS with concurrent E. coli bacteremia.

Orientia tsutsugamushi DNA load and genotypes in blood as a marker of severity.

Scrub typhus is an acute febrile illness caused by Orientia tsutsugamushi and is endemic to many parts of the Asia-Pacific region. We investigated whether the genotype of O. tsutsugamushi or the DNA load would be a useful marker of disease severity in scrub typhus patients. We evaluated the clinical features, genotypes and bacterial DNA load in the blood of 118 patients, including 114 surviving and 4 non-surviving patients, admitted at Chosun University Hospital. Four patients infected with the Pajoo, Yonchon, Youngworl and Boryong genotypes died. In the 114 survivors, 100 Boryong and 2 Taguchi genotypes were identified. The genotypes involved showed significant differences between the surviving and non-surviving patients (p<0.001). The median number of O. tsutsugamushi DNA copies was 78 copies /µL (range 3,960) in surviving patients, whereas 83,800 copies/µL (range 244,600) in the non-surviving patients. We found that the genotype and DNA load in the patient's blood are useful markers of disease severity in scrub typhus.