Tick-Borne Infections: Avoid Exposing Skin during Outdoor Activities

Editorial

17:44 JST, August 18, 2025

Tick bites that result in viral infections can occur not only while camping and during other outdoor activities in the mountains, but also while weeding in a garden. Diseases caused by these infections have a high mortality rate and should not be taken lightly.

The number of patients with severe fever with thrombocytopenia syndrome (SFTS) — an infectious disease transmitted by ticks — is on the rise. As of Aug. 3, there were 124 reported cases this year, already approaching the annual record of 134 people in 2023.

Ticks that transmit the SFTS virus live in the mountains and grassy areas. Unlike tiny mites that are barely visible, ticks are several millimeters long.

The virus was first identified in China in 2011. First confirmed in Japan in 2013, more than 100 cases of infection have been reported in the country every year in recent years.

With symptoms such as fever, vomiting and diarrhea, the disease is also characterized by a decrease in blood platelets. When severely affected, patients suffer from bleeding and consciousness disorders. The fatality rate is said to be as high as 30%.

The majority of people contracting the virus are age 60 or older. Elderly people with reduced physical strength are at high risk of becoming seriously ill, so special care must be taken to prevent them from becoming infected.

Until recently, most cases of infection were reported in western Japan. However, since last month, cases have been confirmed in Kanagawa Prefecture and Hokkaido. There is no doubt that the risk of infection is expanding to eastern Japan.

The central and local governments should analyze infection trends and provide detailed information to raise awareness among the public.

People infected with the SFTS virus have an incubation period of six to 14 days. Those who develop symptoms need to see a doctor. In addition to symptomatic measures such as fever reducers, antiviral drugs for influenza are approved for treating the disease.

It is important to take measures to prevent being bitten by ticks.

When engaging in outdoor activities during summer vacations, it is desirable to wear long-sleeve shirts and trousers that do not expose the skin. Wrapping a towel around the neck and using insect repellent are also effective measures.

When a tick is found stuck on the skin, it is important to be careful not to pull it off forcefully, as this may cause the tick’s bodily fluids to enter the system. It is best to have the tick removed by a dermatologist.

There have also been confirmed cases of dogs and cats contracting the virus from ticks. There is also a risk of transmission to people who come into contact with infected pets. People should be careful if they let their cats go outside freely.

In May, a veterinarian in Mie Prefecture died after treating a cat for SFTS and contracting the virus. When handling pets that appear to be ill, it is essential to take thorough precautions against infection such as wearing gloves and masks.

(From The Yomiuri Shimbun, Aug. 18, 2025)