What is the system for monitoring notifiable diseases?

Established at the end of the 19th century by the law of November 30, 1892, the system for notifiable diseases (MSO) is a cornerstone of the surveillance and prevention of epidemic risks.

Since its inception, this system has evolved both in terms of how it operates and the list of diseases covered. It has also undergone several updates to adapt to new practical requirements related to data transmission and investigations conducted by the Regional Health Agencies (ARS) and Santé publique France, while incorporating rules regarding the protection of personal data.

The principle of so-called notifiable diseases (MSO) is established by Article L 3113-1 of the Public Health Code (CSP), an excerpt of which is provided below:

“Physicians and the heads of public and private medical biology services and laboratories shall report
: “1° To the Regional Health Agency, cases of diseases
requiring urgent local, national, or international intervention; “2° To the National Public Health Agency, cases of diseases requiring special surveillance for the protection of public health. (…)”

Note: This system is based on a legal obligation for all physicians and medical biology laboratories, regardless of their practice setting (public or private), to report to the competent health authorities any cases of disease they diagnose or suspect, provided the disease is included on the list of notifiable diseases.

Mandatory reporting is sometimes only one of the measures used to monitor certain of these diseases. It does not exempt from other procedures that may need to be implemented, such as when these diseases result from nosocomial transmission. Thus, Legionnaires’ disease acquired in healthcare facilities is subject to both mandatory reporting and reporting of nosocomial infections (see the thematic dossier on the reporting of nosocomial infections: healthcare-associated infections dossier).

What are the objectives of surveillance for notifiable diseases?

For notifiable diseases requiring urgent intervention, mandatory reporting enables the swiftest possible implementation of control measures or preventive actions.

For example, the reporting of an invasive meningococcal infection, a foodborne illness outbreak (Tiac), a case of Legionnaires’ disease, or lead poisoning triggers specific investigations by the ARS and/or Santé publique France. These investigations allow for:

• where applicable, to identify other cases,
• to trace the source of the contamination,
• implement preventive or corrective measures such as antibiotic prophylaxis and vaccination of individuals in contact with cases of invasive meningococcal infection, investigate the food consumption of individuals affected by a foodborne illness outbreak (FBI) to identify the food responsible, inspections and disinfection of cooling towers responsible for clusters of Legionnaires' disease.

For all MSOs, the transmission of detailed individual data is intended for the epidemiological surveillance of these diseases. It enables the analysis and monitoring of the temporal and spatial trends of these diseases and the characterization of affected populations in terms of sociodemographic factors, risk factors, and exposure, in order to better target local and national prevention and control efforts. These data thus enable the evaluation and adaptation of public health policies, such as the prevention of HIV infection or acute hepatitis B, the fight against lead poisoning in minors, and the adaptation of vaccination strategies.

What criteria are used to include a disease on the MSO list?

In light of the objectives described above, adding a disease to this list reflects the government’s commitment to gathering information on that disease to protect public health.

Two sets of criteria were defined in 1999 (BEH No. 47/1999 of November 23, 1999) by a multidisciplinary working group of the French Higher Council of Public Health.

Key public health criteria

• diseases that warrant exceptional measures at the international level, such as plague, cholera, yellow fever, or poliomyelitis, which the Ministry of Health must report to the World Health Organization (WHO) under the International Health Regulations (IHR). The reappearance of smallpox cases would also trigger immediate international intervention in the current context of the disease’s eradication,
• diseases requiring urgent intervention at the local, regional, or national level: their reporting triggers investigations, preventive measures (invasive meningococcal infection, diphtheria, tuberculosis, etc.), and corrective measures to address the source of contamination (mass foodborne illness, Legionnaires’ disease, lead poisoning in children, etc.),
• diseases for which an evaluation of prevention and control programs carried out by public authorities is necessary to assess their effectiveness and, if needed, adapt them (AIDS, tuberculosis, tetanus, measles, etc.),
• serious diseases for which it is necessary to assess and monitor mortality, morbidity, and the risk of sequelae (HIV infection at any stage, Legionnaires’ disease, etc.),
• diseases for which there is a need for knowledge (Creutzfeldt-Jakob disease, mesotheliomas, etc.).

Feasibility criteria

• the disease must not be too common to ensure a high level of reporting and enable a rapid response from decentralized services,
• the availability of a simple and specific case definition or classification to facilitate reporting,
• reporting must be accepted by the medical community and by society,
• the cost of implementing the DO for stakeholders must remain proportionate to the public health challenges posed by disease surveillance.

Note: The list of notifiable diseases is not fixed and evolves based on the emergence of new pathogens, the resurgence of old diseases within the country, or surveillance needs dictated by public health policies at the national or international level.

Who are the parties involved in mandatory reporting?

Mandatory reporting is based on the mandatory transmission of individual data to the competent health authority. The procedures are described in Articles R3113-1 through R3113-7 of the Public Health Code. The NCD surveillance system relies on the active involvement of three stakeholders who operate in a chain.

Reporters: clinical laboratories and physicians

The reporting requirement applies to medical biologists, heads of hospital departments and public and private clinical laboratories, as well as private and hospital-based physicians who suspect and diagnose these diseases.

Authorized ARS personnel for diseases requiring intervention

As stipulated in Article R3113-3 of the Public Health Code, mandatory reports of diseases requiring urgent intervention are addressed to authorized ARS personnel, specifically designated by the ARS Director General for this purpose. They work in the field to prevent and reduce, at the local level, the risks of disease occurrence and spread. They may share strictly necessary information with other professionals when their involvement is essential for implementing individual and collective prevention measures. They also play a vital role in validating and transmitting high-quality data to Santé publique France—steps that are essential to ensuring the validity of subsequent surveillance analyses conducted on this basis. As a central link in the system, authorized personnel in the Regional Health Agencies (ARS) and their collaborators also play a major role in relaying information and raising awareness among reporting entities regarding the challenges of health surveillance at the local level.

Épidemiologists at Santé publique France (at the national and regional levels) support or coordinate urgent investigations and handle diseases requiring surveillance

As part of the surveillance of MSOs, Santé publique France epidemiologists, at the regional and national levels, centralize all data in a pseudonymized form, analyze it, and transmit the results of these analyses to public authorities along with recommendations on the measures or actions to be implemented. 

They may also provide scientific expertise to the Regional Health Agencies (ARS) for epidemiological investigations, particularly during outbreaks. They also ensure that the results of their analyses are communicated to stakeholders within the system, the medical and scientific community, and the public.

The Ministry of Health, and more specifically the Directorate General of Health (DGS), receives health alerts issued by the ARS and by Santé publique France and, as needed, participates in risk management decisions in coordination with the ARS. 

Surveillance results generated from the analysis of MSO data are made public in various formats (epidemiological bulletins, scientific publications, etc.), accessible through thematic dossiers and made available as open data via the Odissé portal at varying intervals (at least annually) depending on the frequency of diseases. In particular, they are made available to reporting entities and the departments of the Ministry of Health, which use them to define and adapt public health policies.