The last decade has seen a surge in the incidence of tick-borne-diseases (TBD) in Japan, of which its two principal forms are Japanese Spotted Fever (JSF) and Severe Fever with Thrombocytopenia Syndrome (SFTS)1. The former caused by bacteria Rickettsia japonica and SFTS caused by SFTS virus (SFTSV), are both transmitted by tick bites from a diverse number of tick species in Japan and other countries in east and south east Asia.

Drawing from a wealth of existing clinical and laboratory surveillance data, with this project we aim at 1) Describe the principal epidemiological features of these two diseases in Japan; 2) Understand the transmission dynamics of these diseases, and 3) Provide plausible scenarios to explain the surge in incidence in the last decade.

The project will be structured around the following 4 pillars:

• Data analysis of clinical records: using data on PCR confirmed cases of Japanese spotted fever (JSV) and SFTS in selected Japanese prefectures, we will aim to build a detailed profile of the disease in terms of case fatality rate, duration of symptoms, comorbidities, age/sex patterns. For this, we will apply data analysis skills and basic epidemiology methods.

• Identifying hotspots of TBD in Japan: Looking initially at location of reported cases and matching with laboratory extended location data, try to identify spatial patterns in the occurrence of SFTS and JSF in Japan. Spatial analytics and further data analysis skills well be developed and applied during this phase.

• Serological survey: In coordination with National Institute of Infectious Diseases (NIID) and NU In order to have an estimation of exposure to these diseases in selected areas, a serological survey in population and animal hosts living in previously defined hot spot areas.

• Transmission dynamics of JSF and SFTS in Japan: using mathematical modelling and infectious disease epidemiology skills, this aims to build a mechanistic model for these diseases relying on the previously assessed data. This will aim to provide a mechanistic framework for understanding potential drivers behind the recent increase in SFTS and JSF reporting.

References

1. Severe Fever with Thrombocytopenia Syndrome: Japan under Threat from Life-threatening Emerging Tick-borne Disease. JMA J 3, (2020).