Position: Associate Professor

MAIL: sakamoto65 [at]

Research Departments

Environmental Coexistence


Field Medicine

Research Interests

Community Based Elderly Care in the Kingdom of Bhutan
Potential sources of Legionnaires’ disease
Health status and quality of life among the elderly living in highlands
Health effects of exposures to mercury

Community Based Elderly Care in the Kingdom of Bhutan
According to United Nations, at the global level, 5 per cent of the population was at least 65 years of age in 1950. By 2009, this proportion had increased to just under 8 per cent. By 2050, 16 per cent of the world population is projected to be 65 year or over. According to the government of the Kingdom of Bhutan, the number of the aged 65 years or over was 29745 in 2005 and the number will double by 2030. From October 2010 to March 2011, we conducted medical checkup for the elderly in Khaling, the Kingdom of Bhutan in cooperation with Ministry of Health. Totally 192 people aged 65 years or over participated into the checkup. We assessed disability, dementia, depression, diabetes, dental problem, isolation, hypertension, alcohol problem, visual problem, ear problem, fall, urinary incontinence, and nutrition (5 Ds, I HAVE FUN for short) of the elderly. We should include not only people who come to medical facilities but also people who do not come to the facilities because some elderly people cannot come to the facilities even if they want to. There is a possibility that such people have severe diseases and we have to take care with special attention. Although there are issues of manpower, medical staff should visit the houses of the elderly if needed. The community geriatric care we are conducting now in Khaling is to promote health of the elderly through the comprehensive activities. Health checkup is an important opportunity to grasp problems around the elderly and to prevent the elderly from future diseases, disabilities, and deaths. The elderly should be cared through collaborations with family, neighbors, village heads, medical facilities, schools, and so on. We hope the program will trigger and help to build up the bond and harmony in the communities.

Potential sources of Legionnaires’ disease
Legionella pneumophila bacteria are a major cause of severe community-acquired pneumonia; in recent years the numbers of reported cases of legionellosis have increased substantially where testing is available (e.g., United States, Europe, Japan). However, the source and mode of transmission for sporadic cases are often obscure. We have shown that L. pneumophila can be easily isolated from rainwater on roads, especially during warm weather, which indicates the possibility of frequent contact with L. pneumophila–containing aerosols because L. pneumophila may be splashed from puddles into surrounding air. To decrease death from legionellosis, we should consider the possibility of legionellosis for pneumonia patients, even those who had not traveled or visited spa facilities and pay attention to the potential sources around our living environments.

Health status and quality of life among the elderly living in highlands
Oxygen exchange in humans requires the intake of oxygen into the lungs, the combination of oxygen with the hemoglobin in blood, circulation through the entire body and along with the metabolism of food, entrance into the mitochondria of cells where it participates in making energy required for activity in the form of ATP. When people who live in lowlands go to a high-altitude environment, oxyecoia partial pressure falls with altitude and is said to be about 70% at an altitude of 3000 m. How We would like to determine the effect of high altitude environment and the methods of adaptations on health status and quality of life among the elderly who have been living at high altitude for their whole lives.

Health effects of exposures to mercury
Mercury is known to be a neurotoxin. In Nusa Tenggara Barat, Indonesia, mercury-dependent artisanal and small-scale gold mining is common. We started the preliminary study on health effects of mercury poisoning in these area in cooperation with Faculty of Medicine, Mataram University. There is a possibility that villagers are unprotected from mercury poisoning. We try to proceed cautiously based on the needs of villagers and ethical considerations.


  • 1. 坂本龍太「ブータンの小さな診療所」、pp. 1-195. ナカニシヤ出版、京都市. 2014年
  • 2. 坂本龍太「チベットに暮らす人々の老いと高所環境」池口明子、佐藤廉也(編著)『身体と生存の文化生態』pp. 159-174. 海青社、大津市. 2014年
  • 3. Tsukihara T and Sakamoto R. A village in the sky in Ladakh. In Okumiya K (ed.) Aging, Disease and Health in the Himalayas and Tibet. pp. 103-131. Rubi Enterprise, Dhaka, Bangladesh. 2014
  • 4. 坂本龍太、奥宮清人「健康・疾病」総合地球環境学研究所(編著)『地球環境学マニュアル2』pp.88-89. 朝倉書店、東京都. 2014年
  • 5. 坂本龍太「高所と酒」、奥宮清人編『生老病死のエコロジー 続 ヒマラヤとアンデスに生きる身体・こころ・時間』pp. 225-227. 昭和堂、京都市. 2013年
  • 6. 月原敏博、坂本龍太.「天空の村、ラダーク-チベット文化に生きる健康と幸福」、奥宮清人編『生老病死のエコロジー-チベット・ヒマラヤに生きる』pp. 111-145. 昭和堂、京都市. 2011年
  • 7. 中原俊隆、里村一成、岩永資隆、野網恵、犬塚裕章、日下慶子、坂本龍太、原野和芳. 北川定謙監修、中原俊隆編集『衛生法規の要点 保健・医療に従事する人のために』(2010年版) 日本公衆衛生協会、東京都. 2010年
  • 8. 坂本龍太「ラダックの人々の「幸せ」とは」. 『山と自然に魅せられて』. 山岳科学ブックレット, 3. pp.94-96. オフィスエム、長野市. 2009年
  • 9. 坂本龍太「心肺蘇生」衞藤隆、中原俊隆編『学校医・学校保健ハンドブック』pp. 516-521. 文光堂、東京都. 2006年
  • 10. 中原俊隆、里村一成、岩永資隆、坂本龍太、野網恵. 北川定謙監修、中原俊隆編集『衛生法規の要点 保健・医療に従事する人のために』日本公衆衛生協会、 東京都. 2005年


    Main Research Articles

  • 1. Sakamoto R, et al. Detection of Legionella species from rainwater on roads in Bhutan. Himalayan Study Monographs 2017; 18: 80-86.
  • 2. Sakamoto R, et al. Sleep quality among elderly high-altitude dwellers in Ladakh. Psychiatry Research 2017; 249: 51-57.
  • 3. Sakamoto R, et al. Health and happiness among community-dwelling older adults in Domkhar valley, Ladakh, India. Geriatrics & Gerontology International 2017; 17: 480-486.
  • 4. Sakamoto R, et al. Legionnaire’s disease, weather and climate. Bulletin of the World Health Organization 2015; 93: 435-436.
  • 5. Sakamoto R, et al. Oxidized low density lipoprotein among the elderly in Qinghai-Tibetan plateau. Wilderness & Environmental Medicine 2015; 26: 343-349.
  • 6. Sakamoto R, et al. Predictors of difficulty in carrying out basic activities of daily living among the old-old: a 2-year community-based cohort study. Geriatrics & Gerontology International 2016; 16: 214-222.
  • 7. Sakamoto R, et al. Legionella pneumophila was isolated at high altitude in Tibetan plateau. High Altitude Medicine & Biology 2014; 15: 209-210.
  • 8. 坂本龍太. ブータン王国におけるVillage Health Worker. ヒマラヤ学誌 2012; 13: 242-253.
  • 9. Sakamoto R, et al. Subjective quality of life among the community-dwelling elderly in Bhutan compared with those in Japan. Journal of the American Geriatrics Society 2011; 59: 2157-2159.
  • 10. Sakamoto R, et al. Comprehensive geriatric assessment of elderly highlanders in Qinghai, China, III: oxidative stress and aging in Tibetan and Han elderly highlanders. Geriatrics & Gerontology International 2009; 9: 352-358.
  • 11. Sakamoto R, et al. Is driving a car a risk for Legionnaires’ disease? Epidemiology & Infection 2009; 137: 1615-1622.
  • 12. Sakamoto R, et al. Legionella pneumophila in rainwater on roads. Emerging Infectious Diseases 2009; 15: 1295-1297.
  • 13. Sakamoto R, et al. A patient with Legionnaires’ disease transferred after a traffic accident. BMJ Case Reports 2009 bcr09.2008.0893.
  • 14. Sakamoto R, et al. Second-hand smoke in restaurants after enforcement of a Health Promotion Law in Japan. Journal of Public Health Policy 2007; 28: 156-161.
  • 15. Sakamoto R, et al. Hospitals’ measures against passive smoking. Tobacco Counters Health 2006; 4: 23-27.