Public health issues in the 21st century: National challenges and shared challenges for the Maghreb countries.

In the 21st century, public health is not only about fighting infectious diseases, but also contributing to a "multidimensional" well-being of people (health promotion, non-communicable diseases, the role of citizens and people in the health system etc.). Six themes of public health, issues of the 21st century will be addressed. Climate change is already aggravating already existing health risks, heat waves, natural disasters, recrudescence of infectious diseases. Big data is the collection and management of databases characterized by a large volume, a wide variety of data types from various sources and a high speed of generation. Big data permits a better prevention and management of disease in patients, the development of diagnostic support systems and the personalization of treatments. Big data raises important ethical questions. Health literacy includes the abilities of people to assess and critique and appropriate health information. Implementing actions to achieve higher levels of health literacy in populations remains a crucial issue. Since the 2000s, migration flows of health professionals have increased mainly in the "south-north" direction. India is the country with the most doctors outside its borders. The USA and the UK receive 80% of foreign doctors worldwide. Ways have been identified to try to regulate the migratory phenomena of health professionals around the world. The mobilization of citizen, health system users and patient associations is a strong societal characteristic over the last 30 years. In a near future, phenomena will combine to increase the need for accompaniment of patient or citizen to protect health, such increase of the prevalence of chronic diseases, reinforcement of care trajectories, medico-social care pathways, and importance of health determinants. Interventional research in public health is very recent. It is based on experimentation and on the capitalization of field innovations and uses a wide range of scientific disciplines, methods and tools. It is an interesting tool in the arsenal of public health research. It is essential today to be able to identify the multiple challenges that health systems will face in the coming years, to anticipate changes, and to explore possible futures.