But before the man returned to his office the next day, his employer had received an unsolicited call from the hospital revealing the employee was suffering from TB. The hospital did not think it was doing anything wrong: it was merely following Japanese custom by placing the welfare of the group (in this case the man's colleagues) above the rights of the individual.
The man will spend some time convalescing, and then will return to his old job, which will be held open for him. But not all employers would be so understanding - particularly if the disease in question were Aids.
Concerns that doctors do not preserve their patients' confidentiality have led a growing number of Japanese to travel to a special clinic in Hawaii to have tests for HIV, the virus that can lead to Aids. And some of those who have tested positive have opted to stay in Hawaii rather than return to Japan, where Aids has been stigmatised as a 'foreigner's disease'.
The Waikiki Health Centre in Honolulu has been running an HIV-test service for Japanese speakers since 1992, and has 20 volunteers from Japan to deal with patients who cannot communicate in English. The Japanese Outreach Programme was originally established for Japanese living in Hawaii, but began attracting people from Japan who were afraid that doctors at home would reveal positive test results to their employers.
The level of prejudice against Aids in Japan was vividly demonstrated last weekend when the Minister of Health, Keigo Ouchi, told a meeting of his party's members: 'Asian nations that surround Japan are all Aids countries.' In a speech that outraged Aids support groups, Mr Ouchi said that 'with the exception of Japan, the units that go on United Nations peace-keeping operations from other countries all come back infected with Aids'.
Last month, the Ministry of Health and Welfare said there were 1,356 HIV-positive people in Japan. But because doctors are known to pass on medical records to third parties, such as employers or relatives, it is feared that many people who believe they might have been exposed to HIV do not dare to go for a test.
'People are suspicious of low confidentiality,' said Megumi Baba, an Aids counsellor from Japan who runs the Outreach programme in Honolulu. 'Culturally Japan has not faced up to the confidentiality/individuality issue.'
Ms Baba has been doing research at the University of Hawaii's School of Medicine for four years. She established the Outreach programme because of the large number of Japanese students and other young people living in Hawaii.
Two or three people a week now make the seven-hour plane journey to Hawaii from Tokyo to have the test, which takes seven days to process. The test is free, but the plane ticket and a week's stay at a hotel would cost at least pounds 1,500. Ms Baba has also set up a telephone hotline service in Japanese, offering counselling on Aids, prevention, and general sexual problems. Many of the calls made to the hotline originate in Japan.
'Gay people feel uncomfortable talking about their sexuality in Japan. Sometimes they just call us for advice on how to avoid contracting HIV. Then there are people who have to have health tests in their company, and want to find out beforehand. They are all unhappy to ask a professional in Japan. One person even rang to say 'I have HIV, I can't tell my family or friends, can I come over there to die?' '
Ms Baba's programme has received wide - and mostly sensational - coverage in the Japanese media. She has made presentations to Aids support groups and government agencies in Japan. But she says bureaucrats do not want to confront the problem of patients' mistrust of the medical system. 'They say I am too influenced by America, and do not understand Japanese culture' - even though she is Japanese. 'Aids has brought up this issue of the rights of the individual. But the Ministry of Health - they don't get it. They just don't understand.'