Spotted fever group rickettsiae (SFGR) detection in ticks following reported human case of Japanese spotted fever in Niigata Prefecture, Japan

Chika Hirokawa,Tsutomu Tamura,Junko Aoki,Marcello Otake Sato,Akiko Nishida,Sumire Ikeda,Reiko Arai,Maria Angenica F Regilme,Kozo Watanabe,Kaori Watanabe,Miwako Kato,Megumi Sato

doi:10.1038/s41598-021-81587-9

Chika Hirokawa, Tsutomu Tamura + Show 10 more

Open Access

https://doi.org/10.1038/s41598-021-81587-9

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Abstract

Japanese spotted fever, a tick-borne disease caused by Rickettsia japonica, was firstly described in southwestern Japan. There was a suspicion of Rickettsia japonica infected ticks reaching the non-endemic Niigata Prefecture after a confirmed case of Japanese spotted fever in July 2014. Therefore, from 2015 to 2017, 38 sites were surveyed and rickettsial pathogens were investigated in ticks from north to south of Niigata Prefecture including Sado island. A total of 3336 ticks were collected and identified revealing ticks of three genera and ten species: Dermacentor taiwanensis, Haemaphysalis flava, Haemaphysalis hystricis, Haemaphysalis longicornis, Haemaphysalis megaspinosa, Ixodes columnae, Ixodes monospinosus, Ixodes nipponensis, Ixodes ovatus, and Ixodes persulcatus. Investigation of rickettsial DNA showed no ticks infected by R. japonica. However, three species of spotted fever group rickettsiae (SFGR) were found in ticks, R. asiatica, R. helvetica, and R. monacensis, confirming Niigata Prefecture as a new endemic area to SFGR. These results highlight the need for public awareness of the occurrence of this tick-borne disease, which necessitates the establishment of public health initiatives to mitigate its spread.

Highlights

Japanese spotted fever is a tick-borne disease caused by Rickettsia japonica; the disease was first described in Tokushima Prefecture in southwestern Japan and named by Mahara (1989; 1985)[1]
We collected D. taiwanensis, H. hystricis, H. megaspinosa, I. columnae, and I. monospinosus species not observed in the previous study, showing the presence of ticks may have been influenced by the environmental change and hosts movement (Sato et al, in preparation)
spotted fever group rickettsiae (SFGR) positivity in adult ticks in Niigata Prefecture was 5.6%, and it is similar to the positivity rate of the neighboring prefecture, Toyama, with 3.3%15

Summary

Introduction

Japanese spotted fever is a tick-borne disease caused by Rickettsia japonica; the disease was first described in Tokushima Prefecture in southwestern Japan and named by Mahara (1989; 1985)[1]. In recently described cases of Spotted Fever Group Rickettsiae (SFGR), the disease is caused by species other than R. japonica[3,4]. After an epidemiological investigation on the confirmed case of Rickettsia japonica occurred in Niigata Prefecture, the most probable place of contact with ticks was near the patient’s house in an urban area despite no ticks were collected for identification. This study was conducted to detect the tick prevalence and SFGR prevalence by species of ticks in Niigata Prefecture after the occurrence of a Japanese spotted fever human case

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