Unlike many people who live in Tokyo, I love the Japanese summer. I like the screech of the cicadas, the sweaty street festivals. I like the firework displays. I even like the intense heat. It has always struck me that Japan has all the exoticism of a tropical summer without the usual attendant maladies. Until last week that is, when three classmates from Saitama and Tokyo all contracted dengue fever, making them the first people to be infected with the mosquito-born illness in Japan since the 1940s.
Around 200 Japanese travellers a year come back from holiday with the illness, which causes high fever and joint pain although, if treated quickly, is rarely fatal, but there had been no domestic infections for nearly 70 years.
The first infection was announced on Wednesday, the second two on Thursday. The link between them was that they had all been bitten by mosquitoes in Yoyogi Park last month while rehearsing dances for an upcoming festival. Yoyogi Park is one of central Tokyo’s biggest and busiest parks; it’s next to Harajuku and Meiji Shrine and it’s packed with people all year round, many of whom are using the open space to practice musical instruments, sing and work on dance routines.
The thought that it had been the source of a tropical illness was alarming and the authorities took swift action. The word spread around the neighbourhood: fumigation was imminent. At 54 hectares the park is enormous but investigations pinpointed a small area, 50 metres in radius, which was sprayed by men in head-to-toe white suits on Thursday evening.
One man who might be justified in feeling vindicated is Mutsuo Kobayashi, an honorary member of Japan’s National Institute of Infectious Diseases who has been urging the government to take action on dengue. He has been saying that rising temperatures are increasing the prospect of dengue-infected mosquitoes appearing in northern Japan. The tiger mosquitoes that carry the illness are already living as far north as Aomori and are expected to reach Hokkaido by the end of the century. Earlier in the year, Kobayashi said that Japan has become a country with the risk of dengue fever.
Yoyogi Park was, inevitably, quieter this weekend. According to the World Health Organisation there are anywhere up to 100 million cases of dengue fever in the world each year, but the chances of contracting the illness in Japan are still tiny. Dengue is not transmitted from person to person, only by mosquitoes, and the assumption is that this unlucky trio were bitten by mosquitoes that had picked up the virus from people who’d come from outside Japan. Still, one person’s trouble is another’s gain: shares in Japan’s insecticide makers have reportedly soared.
Fiona Wilson is Monocle’s bureau chief for Asia