Emerging Tick-Borne Infectious Disease "Severe Fever with Thrombocytopenia Syndrome (SFTS)": Latest Trends and Countermeasures

Table of Contents

1. What is SFTS

2. Pathogen and Transmission Route Elucidation

3. Symptoms and Clinical Course

4. Latest Statistics and Regional Distribution in Japan

5. Trends in Asia and Worldwide

6. Current Status of Treatment and Vaccine Development

7. Preventive Measures: Individuals, Society, and Domesticated Animals

8. High-Risk Groups and Factors for Severe Cases

9. Infection Control in Medical and Veterinary Settings

10. Future Prospects and Summary
    
    

1. What is SFTS

SFTS (Severe Fever with Thrombocytopenia Syndrome) is a severe febrile hemorrhagic disease caused by the SFTS virus (SFTSV) of the genus Bandavirus, family Phenuiviridae. It was first reported in China in 2009 and identified in Japan in 2013 as an emerging infectious disease. Its main characteristics include high fever, thrombocytopenia, leukopenia, and multiple organ failure, with a high fatality rate being its greatest threat.mhlw.go.jpwwwnc.cdc.gov

Classification and Characteristics of the Virus

• It has a tripartite negative-sense RNA genome.

• It is divided into six major genotypes (A-F), with the dominant type varying by region.wwwnc.cdc.gov

• The incubation period is 6-14 days.
  
  

2. Pathogen and Transmission Route Elucidation

Tick-Borne

In Japan, multiple species such as Haemaphysalis longicornis and Amblyomma testudinarium act as vectors, and recently,human infection by the non-native species H. aborensishas also been reported.wwwnc.cdc.gov

Other Routes

• Human-to-Human Transmission: Nosocomial infections through direct contact with blood and bodily fluids were first confirmed domestically (2024).niid.go.jp

• Animal-to-Human Transmission: Cases where infection occurs from symptomatic cats and dogs to their owners.
  
  

3. Symptoms and Clinical Course

It begins with fever, gastrointestinal symptoms (vomiting, diarrhea), headache, and muscle pain, and progresses to bleeding tendencies, consciousness disturbances, and DIC, becoming fatal. The domestic fatality rate is reported to be about 27%, with elderly and individuals with underlying conditions being more prone to severe cases.niid.go.jp

4. Latest Statistics and Regional Distribution in Japan

The prefectures with the most reports are mainly in western Japan, such as Kagoshima, Miyazaki, Ehime, and Kochi. Meanwhile, sporadic cases are also found north of Kanto.In 2024, multiple cases of non-SFTS virus tick-borne encephalitis were reported in Hokkaido, sparking discussions on the overall risk of tick-borne infectious diseases.niid.go.jp

5. Trends in Asia and the World

• South Korea and China: Hundreds of cases are reported annually.

• Southeast Asia: In Thailand, SFTSV RNA was detected in 1.6% of patients with acute febrile illness, and infections were confirmed in rodents and ticks.wwwnc.cdc.gov

• WHO's Position: Due to the lack of vaccines and high fatality rate, SFTS is being promoted as a high-priority emerging infectious disease for research.iris.who.int
  
  

6. Current Status of Treatment and Vaccine Development

• Supportive Therapy as a Basic: Infusion, platelet transfusion, organ support.

• Antiviral Drug Candidates: Ribavirin is insufficiently effective. The effectiveness of Favipiravir, conditionally approved in 2024, is at the case report stage.mhlw.go.jp

• Vaccine Research: DNA vaccines and VLP vaccines are in the preclinical stage.
  
  

7. Preventive Measures: Individuals, Society, and Domestic Animals

Measures Individuals Can Take

1. Preventing Skin Exposure Outdoors: Long sleeves and pants, socks covering the ankles.

2. Use of Repellents (DEET, Icaridin).

3. Tick Check After Returning Home: Check the entire body during bathing.

4. Avoid Unnecessary Contact with Stray Cats and Dogs.

5. Seek Early Medical Attention if Symptoms Appear.
   
   

Domestic Animals

Regularly prescribe tick repellents at animal hospitals for pets and make brushing after walks a habit.

Social Infrastructure

Local governments are strengthening awareness through grass cutting and sign installation. Monitoring non-native ticks is also urgent.

8. High-Risk Groups and Factors for Severe Cases

Elderly people, those with diabetes, cardiovascular diseases, or immunosuppressed conditions have a higher fatality rate. Agricultural and forestry workers, as well as outdoor enthusiasts, are at high exposure risk, necessitating local healthcare to prepare awareness and early diagnosis systems.mhlw.go.jp

9. Infection Control in Medical and Veterinary Settings

When handling blood and body fluids of suspected SFTS patients, standard precautions along with contact and droplet precautions must be enforced. There have been reports of infections from cats to veterinarians, making PPE essential in veterinary settings as well.mhlw.go.jp

10. Future Prospects and Summary

• Due to climate change and the expansion of wildlife habitats, there is a possibility that the SFTS risk, including non-native tick species, will become nationwide.

• Pharmaceutical Development is progressing internationally, but establishing clinical evidence will take time.

• Tick avoidance behavior at the citizen level and early medical intervention are realistic and immediate measures.
  
  
  

SFTS is transitioning from a localized outbreak to a nationwide concern. It is crucial to share the latest information domestically and internationally and for the government, healthcare, and citizens to work together to promote measures against tick-borne infectious diseases.

Reference Article List

• Ministry of Health, Labour and Welfare "Guidelines for the Management of Severe Fever with Thrombocytopenia Syndrome (SFTS) 2024 Edition"mhlw.go.jp

• National Institute of Infectious Diseases "Overview of SFTS Cases Reported in the Infectious Disease Surveillance as of January 31, 2025"niid.go.jp

• CDC Emerging Infectious Diseases "Comprehensive Surveillance of SFTS Virus, Thailand 2015-2021"wwwnc.cdc.gov

• CDC Emerging Infectious Diseases "Transmission of SFTS Virus to Human from Non-indigenous Tick Host, Japan (2024)"wwwnc.cdc.gov

• NIID "First Confirmed Case of Human-to-Human Transmission of SFTS in Japan"niid.go.jp

• WHO R&D Blueprint "Priority Emerging Diseases List (SFTS Item)"iris.who.int