• Expatriate children;
  • Hygiene hypothesis;
  • Living environment;
  • Oversea life


Aim: To clarify the health-related conditions of Japanese expatriate children in Thailand.

Methods: Records of Japanese children who consulted outpatient clinics at Bangkok Hospital in 2005 and 2006 (n = 2141) were analysed, and then compared with data from the patient survey conducted by the Ministry of Health, Labour and Welfare of Japan in 2005 (n = 575 400).

Results: ‘diseases of the respiratory system’, categorized as chapter X under ICD-10 was the most frequent category in both Thailand and Japan. Although ‘certain infectious and parasitic diseases’ (chapter I) was the second most frequent category in Thailand, it was infrequent in Japan. In the subcategories of ‘diseases of the respiratory system’, ‘acute upper respiratory infections’ was frequent and asthma was infrequent in Thailand. Conversely, ‘acute upper respiratory infections’ showed a low percentage and asthma was the most frequently observed disease in Japan.

Conclusion: This study examined Japanese children having the same genetic background but divided into two groups according to different living environments. Results demonstrate that children living in Japan contract asthma more frequently than infectious diseases, whereas those living in Thailand show the opposite trend, which supports the hygiene hypothesis that infections may protect against the development of allergic diseases, such as asthma.