Nine people have contracted tuberculosis while 34 others have developed asymptomatic forms of the disease after coming into contact last year with an Asian student living in Tokyo, the metropolitan government has revealed.
According to the Tokyo Metropolitan Government’s Social Welfare and Public Health Bureau, the man in his 20s, who came to Japan in April 2015, is living in Tokyo’s Shinjuku Ward, where he attends a Japanese language school.
One Japanese teacher and several other foreign nationals, students at the same school, are among those who have developed symptoms, Yoshiyuki Sugishita, an official with the bureau, told The Japan Times on Wednesday.
“The disease has spread since the first patient began developing symptoms,” Sugishita said, adding that it remained unclear how and when the man contracted the disease.
Metropolitan government officials believe that the student had ignored the symptoms initially. This, combined with the long periods of time spent in the school’s confined space, contributed to the spread of the disease among the students and teacher.
Sugishita said the man, whose identity has been withheld due to privacy concerns, has shown symptoms of the disease, including a nagging cough, since September but, unaware of his condition, continued to attend classes.
He was diagnosed with tuberculosis in November when an abnormality in his chest was discovered through an X-ray test.
Of those who came into contact with the man at the language school, five contracted tuberculosis while 29 were asymptomatic.
Tuberculosis bacteria are usually spread via the air when those with an active form of the disease in their lungs cough, spit, speak or sneeze.
The man has been sharing a living space, and three of the residents also developed similar symptoms, including a dry cough, while infections in two other residents were confirmed via blood tests.
The bacteria apparently also spread at the man’s workplace in Saitama Prefecture, where he works part-time. One person there was found to have an active form of the disease.
The blood tests confirmed latent infections in 34 of 146 people who had contact with the Asian student and underwent medical tests. All have been undergoing treatment to prevent further development of the disease or are under observation, officials said.
According to the bureau, the Asian student has finished his treatment and his condition has improved.
Sugishita warned that the infection may have spread to others who have not had health checkups, but said that most of those in close contact with the student had received medical care.
“There is no ongoing risk of further transmission from those already diagnosed with infections as they have already had treatment,” Sugishita said.
Officials said 10 to 20 percent of tuberculosis cases see symptoms develop between about six and 24 months after infection. Patients with latent forms of tuberculosis are not at risk of spreading the disease.
Although tuberculosis is commonly thought of as a disease modern medicine has conquered, metropolitan government data show that 2,533 new cases were discovered in 2014 in Tokyo alone. The same year, 216 people died from the disease in the capital.