After returning from the Iwakura Mission, Nagayo Sensai became Director-General of the Medical Bureau in the Ministry of Education, positioning hygiene-oriented administrators to steer Western medical policy and training.
The Meiji government issued the Isei (Medical System) law, an early nationwide framework for licensing and organizing medical practice and medical education, helping accelerate the institutional shift toward Western-style medicine.
A dedicated Health (Hygiene) Bureau was established within the Home Affairs Ministry, with Nagayo as its first head—marking a central administrative pivot toward modern public health governance in Japan.
The Hygiene Bureau issued a Smallpox Prevention Regulation, strengthening vaccination policy as an early pillar of Meiji-era disease prevention and state-led public health.
Nagayo Sensai’s office produced an English-language report on choleraic diseases in Japan during Meiji 10 (1877), exemplifying the Bureau’s reliance on reporting and statistics to guide epidemic response and sanitation policy.
Japan promulgated quarantine regulations (including port-level health boards and quarantine anchorages) to prevent cholera spread, reflecting the growing use of border-health controls and organized maritime public health.
Regulations on infectious-disease prevention legally designated key epidemic diseases (including cholera, typhoid, dysentery, diphtheria, typhus, and smallpox), supporting more systematic notification, control, and sanitation measures.
The Dai Nippon Shiritsu Eiseikai (Greater Japan Private Hygiene Association) was established to disseminate hygiene concepts through lectures and public outreach, complementing state policy with civil-society education on prevention and disinfection.
Yokohama introduced Japan’s first modern piped water supply system (using sand filtration), a major sanitation reform aimed at reducing waterborne disease risk in rapidly growing port cities.
After returning from Germany, Mori Rintarō (Mori Ōgai) was appointed lecturer at the Army Medical College, helping embed European medical science and hygiene thinking in military medicine and broader professional training.
Shibasaburō Kitasato founded the private Institute for Infectious Diseases, a landmark for bacteriological research capacity and laboratory-based public health in Japan.
Japan promulgated the Communicable Disease Prevention Law (1897), consolidating and strengthening legal authority for infectious-disease control within the modernizing public health system.
The Institute for Infectious Diseases was transferred to the Ministry of Home Affairs, aligning infectious-disease research more closely with central public health administration.
Introduction of Western Medicine, Public Health, and Sanitation Reforms (1870s–1900s)
