Photo/Illutration The Japan Institute for Health Security in Tokyo’s Shinjuku Ward (Asahi Shimbun file photo)

Health officials are calling for vigilance and precautionary measures as Japan has logged a record number of infections from a potentially fatal tick-borne illness this year.

A total of 135 cases of severe fever with thrombocytopenia syndrome (SFTS) have been reported so far in 2025, according to preliminary data released on Aug. 19 by the Japan Institute for Health Security.

This exceeds the 134 cases reported in 2023, marking the highest count since the infectious disease was first identified in the country in 2013.

SFTS is transmitted through bites from infected ticks, commonly found in grassy areas. Typical symptoms include fever, vomiting and abdominal pain.

According to the health ministry, the disease has a case fatality rate ranging from 10 to 30 percent, with elderly patients at higher risk.

SFTS is also known to infect pets, often with a higher case fatality rate, posing a transmission risk to their owners.

Human cases have been gradually rising, with more than 100 reported annually since 2021.

While infections have traditionally been concentrated in western Japan, cases this year have also been reported in the Kanto region, which includes Tokyo, and as far north as Hokkaido.

Health officials are urging the public to take preventive measures, particularly during the warmer months from spring through fall, when tick activity is at its peak.

Recommendations include wearing long-sleeve shirts and long pants when walking through grassy or forested areas to minimize skin exposure to ticks. 

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