SFTS, a tick-borne viral infection…gradually moving eastward from the center of western Japan
An infectious disease transmitted by ticks, which often results in death, is moving eastward across the Japanese archipelago. The first case in Japan was confirmed about 10 years ago in Yamaguchi Prefecture. Since then, the number of infected people has gradually spread eastward from the center of western Japan.
Not all ticks carry this virus, but tick bites are not limited to agricultural work and grass cutting. Ticks can lurk in the grass in the fields and along riversides, and it is possible to be bitten simply by walking into grassy areas. Furthermore, pets such as dogs and cats infected with the virus can transmit it to humans.
In early June of this year, a woman in her 80s was hospitalized in Hamamatsu City, Shizuoka Prefecture, with a fever and shaky hands after being bitten by a tick while mowing her grass. According to the city’s announcement, the woman had bites on her right cheek and the inside of her right thigh, and was suffering from severe febrile thrombocytopenia syndrome (SFTS), an infection caused by a tick-borne virus.
There is no treatment or vaccine…the first outbreak was reported in China around 2009.
According to the Ministry of Health, Labor and Welfare, SFTS is mainly transmitted by the bite of a tick that carries the virus. In addition to fever, vomiting, abdominal pain, and diarrhea, the disease can cause neurological symptoms such as convulsions and swollen lymph nodes, with a fatality rate of approximately 30%.
The fatality rate is approximately 30%. “There is no cure or vaccine, so the only treatment is coping.
The spread of infected people in Japan is believed to be due to the fact that ticks carrying the virus are carried by wild animals such as deer and wild boars, as well as by the movement of infected animals, which is also believed to be spreading its distribution area.
In Japan, the first case of infection is believed to have occurred in Yamaguchi Prefecture in the fall of 2012, when an adult female was hospitalized with symptoms of fever, vomiting, and diarrhea and died.
In the world, an outbreak was reported in China around 2009, and the causative virus was identified in 2011. Since then, it has been confirmed in other Asian countries.
According to the National Institute of Infectious Diseases, there were 805 reported cases in Japan as of the end of January this year. The age distribution is spread across all age groups, but most of the cases are in their 60s or older, with the median age being 75 years old. From the beginning of this year to late May alone, dozens of cases have been reported nationwide. The number of infected people is said to be higher between May and August.
Tokyo, Toyama and Ishikawa also infected…
At first, the virus was reported mainly in western Japan,” said a person in charge of the Tuberculosis Infectious Diseases Division of the Ministry of Health, Labour and Welfare.
Recently, cases have been reported in Shizuoka and Tokyo on the Pacific Ocean side, and in Toyama and Ishikawa on the Sea of Japan side, indicating that the virus is moving eastward through the archipelago.
For example, the aforementioned case of infection in Hamamatsu City in June of this year was the fifth case in that city and the 12th in Shizuoka Prefecture. According to the prefectural infectious disease control officials, the first person infected in the prefecture was a man in his 60s in March ’21.
On the other hand, the first case of infection in Toyama Prefecture was found last November in a woman in her 60s who was engaged in agriculture. According to the National Institute of Infectious Diseases, the woman complained of fever, loss of appetite, and fatigue, and was prescribed an antipyretic at a medical institution, but her symptoms did not improve. After further examination at the medical institution, she was found to have a sting mark on her right thigh, which was confirmed to be SFTS.
Like this woman in Toyama Prefecture,
“It is said that many people are bitten by ticks and do not even notice it,” says a Ministry of Health, Labor and Welfare official.
says a MHLW official.
Many of the infected cases nationwide were bitten while farming or mowing grass, but there is still a risk of being bitten by a tick lurking in the grass if one’s skin is exposed, even if one only enters grassy areas. The MHLW advises that when entering grassy areas, it is advisable to wear long sleeves, long pants, gloves, and wrap a towel around your neck to minimize skin exposure. The Ministry also recommends wearing brightly colored clothing so that ticks can be easily identified if they are attached.
On the other hand, beware of infection from pets such as dogs and cats. Cases of pets being infected with SFTS have been reported throughout Japan, and there have also been cases of pets infecting humans, possibly because people have come into contact with bodily fluids from pets that have contracted SFTS.
It is advisable to take measures to prevent ticks from biting, but if a tick does bite, parts of the tick may remain if the tick is forcibly pulled out. In addition, the tick’s fluids, which contain pathogens, may enter the body.
If you are bitten by a tick, the Ministry of Health, Labour and Welfare (MHLW) advises
“It is advisable to have the tick removed and cleaned at a medical institution.
“We want you to pay attention to the symptoms after the bite,
“Be aware of the symptoms after the bite.
“Pay attention to the symptoms after the bite.
Interview and text by： Hideki Asai