Work & Conditions
Infectious Disease Reporting and Quarantine in Japan
How Japan's infectious disease surveillance and quarantine system works — legal reporting obligations, how the system responds to outbreaks, and what this means for foreign residents.
Foreign residents diagnosed with a notifiable infectious disease in Japan, or those who want to understand the legal framework for disease reporting and outbreak response.
Japan’s legal framework for infectious disease control
Japan’s infectious disease surveillance and response system operates under the Act on the Prevention of Infectious Diseases and Medical Care for Patients with Infectious Diseases (感染症法, Kansenshō-hō), enacted in 1998 and significantly revised since. The law classifies notifiable diseases into five categories based on severity and public health risk, assigning different response obligations to each.
The National Institute of Infectious Diseases (NIID, 国立感染症研究所) operates the national surveillance system, which compiles reports from prefectural hokenjo and publishes weekly epidemiological data. This data informs public health guidance and outbreak response.
The five disease categories
Category I (一類, ichi-rui): The most severe diseases — Ebola, Marburg, Lassa fever, plague, smallpox, and similar. No patient copayment; full public health authority intervention including immediate hospitalization orders; immediate physician reporting obligation.
Category II (二類, ni-rui): Serious transmissible diseases including tuberculosis, cholera, typhoid fever, paratyphoid fever, poliomyelitis, diphtheria, and SARS. Within-24-hour reporting; hospitalization orders possible; treatment costs managed publicly.
Category III (三類, san-rui): Bacterial food-borne diseases (E. coli O157, Shigella, Salmonella typhi, etc.). Immediate reporting; work restrictions for food handlers.
Category IV (四類, shi-rui): Vector-borne and zoonotic diseases — dengue fever, Japanese encephalitis, rabies, malaria, and others. Within-24-hour reporting; no direct patient hospitalization mandate, but public health investigation required.
Category V (go-rui, 五類): A large group of diseases subject to sentinel surveillance — influenza, COVID-19, measles, rubella, varicella, invasive meningococcal disease, and many others. Reporting intervals range from immediate (for some) to weekly aggregated data (for sentinel sites).
Contact tracing and its scope
When a physician reports a notifiable case to the public health center (hokenjo), the hokenjo initiates an epidemiological investigation. For infectious diseases with person-to-person transmission, this includes identifying and contacting people who may have been exposed. As a contact of a confirmed case, you may be called by the hokenjo for health monitoring, testing, or preventive treatment.
Cooperation with contact tracing is expected and legally supported. The hokenjo staff will explain the purpose of contact and what follow-up is recommended. For foreign residents, some prefectural hokenjo have multilingual staff or can access interpretation services.
Quarantine at ports of entry
Japan maintains quarantine stations (検疫所, kenekijo) at all international ports and airports, operated under the Quarantine Act (検疫法). Travelers arriving from areas with disease outbreaks — as designated by MHLW — may be subject to health screening, medical examinations, or observation requirements at entry. The specific measures depend on the disease and current outbreak status.
During the COVID-19 pandemic, quarantine entry requirements reached their most extensive application in Japan’s modern history. The infrastructure and legal mechanisms used then remain in place and can be reactivated.
Rights during public health intervention
Patients subject to hospitalization orders under the Infectious Disease Control Law retain certain rights: to be informed of the reason for hospitalization and its duration; to receive care appropriate for their condition; and to appeal to the prefectural review board. Patients receiving public health measures should receive written notice of the legal basis for each measure.
Last reviewed: September 2026
Key terms
| English | Japanese | Romaji |
|---|---|---|
| Infectious Disease Control Law | 感染症の予防及び感染症の患者に対する医療に関する法律 | kansenshō-hō (abbreviated) |
| Category I–V diseases | 一類・二類・三類・四類・五類感染症 | ichi-rui / ni-rui / san-rui / shi-rui / go-rui kansenshō |
| Quarantine | 検疫 | ken'eki |
| Hospitalization order | 入院措置 | nyūin sochi |
| National Institute of Infectious Diseases | 国立感染症研究所 | Kokuritsu Kansenshō Kenkyūjo (NIID) |
| Sentinel surveillance | 定点把握 | teiten haaku |
| Contact tracing | 接触者調査 | sesshokusha chōsa |
| Public health center | 保健所 | hokenjo |
Common questions
- Who is required to report an infectious disease in Japan?
- Licensed physicians (doctors) are legally required to report diagnosed notifiable infectious diseases to the local public health center within specified time frames — immediately for Category I diseases, within 24 hours for Categories II–IV, and at defined intervals for Category V sentinel reporting. Patients are not required to self-report but may be contacted by the hokenjo for contact tracing.
- Can the government require me to be hospitalized for an infectious disease?
- Yes, for certain disease categories. Category I diseases (including Ebola, plague, and similar severe diseases) and Category II diseases (tuberculosis, cholera, typhoid, paratyphoid) can result in hospitalization orders from the prefecture governor when public health is at risk. Patients are entitled to appeal and to receive information about their rights.
- Does the infectious disease system apply to foreign nationals equally?
- Yes. Japan's infectious disease laws apply to all persons on Japanese territory, regardless of nationality, visa status, or residency status. Public health interventions — contact tracing, hospitalization orders — apply equally. Treatment for Category I and II diseases at designated infectious disease hospitals is publicly funded.
- What happened during COVID-19 and could similar measures apply again?
- COVID-19 was reclassified as a Category V disease in May 2023, removing most mandatory public health authority measures. Future respiratory pandemics would be handled under the Infectious Disease Control Law, potentially at higher category designations depending on severity — which could include mandatory hospitalization provisions. MHLW maintains pandemic preparedness planning.
Sources
Last reviewed: September 2026