J Korean Med Sci.  2023 May;38(20):e156. 10.3346/jkms.2023.38.e156.

Coinfection of Severe Fever With Thrombocytopenia Syndrome Virus and Coxiella burnetii in Developmental Stage of Hard Ticks in Subtropical Region of Korea

• Yoo JR
• Heo ST
• Kim M
• Kim M
• Kang MJ
• Kim ET
• Kang SY
• Lee KH

• KMID: 2542595
• DOI: http://doi.org/10.3346/jkms.2023.38.e156

Abstract

Background
Severe fever with thrombocytopenia syndrome virus (SFTSV) is transmitted through tick bites. Ticks are potential vectors for the bacterium Coxiella burnetii that causes Query fever. Here, we analyzed SFTSV and C. burnetii co-infection rates in ticks in rural areas of Jeju Island, South Korea.
Methods
Free ticks were collected from the natural environment of the island between 2016 and 2019, and SFTSV RNA was extracted. Additionally, ribosomal RNA gene sequencing was used to identify Coxiella species.
Results
Haemaphysalis longicornis was the most common tick species followed by H. flava. Tick number gradually increased from April, peaked in August, and was lowest in March. Of all the collected ticks, 82.6% (2,851/3,458) were nymphs, 17.9% (639/3,458) adults, and 0.1% (4/3,458) larvae. SFTSV-infected ticks comprised 12.6% of all ticks; their numbers were the lowest in November–December, increased from January, and were mostly identified in the adult stage during June–August. C. burnetii infections were detected in 4.4% of the SFTSVinfected H. longicornis ticks. C. burnetii co-infection was mainly observed in the nymph stage of H. longicornis, with the highest infection rate in January, followed by December and November.
Conclusion
Our findings suggest that Jeju Island has a high SFTSV and potential C. burnetii infection in ticks. This study provides important insights regarding SFTS and Q fever risk to humans in South Korea.

Keyword

Severe Fever With Thrombocytopenia Syndrome Virus; Coxiella burnetii; Q Fever; Ticks; Hemaphysalis longicornis; Jeju-do; South Korea