On 7 April, 1948 the World Health Organization was formally established, with the entry into force of its constitution. For this reason, April 7 is also World Health Day.
The first attempts at cooperation on international public health date back to the mid-19th century, when the first International Sanitary Conference was held in Paris, following the cholera epidemic that had hit Western Europe two years earlier, in 1849; the development of transport and international trade, combined with unhealthy living conditions in overpopulated cities, had facilitated the spread of diseases, bringing the issue of public health to the forefront. The Conference was mainly attended by European states and the main topic was the quarantine measures to be applied to ships in harbors; an important aspect of the Conference was that each state had two representatives: a diplomat and a doctor.
The final convention signed by the parties never actually became operational. By the way, the first Conference was followed by several others between the second half of the 19th century and the first half of the 20th, while in 1907 a convention was signed in Rome by 12 states - Belgium, Brazil, Egypt, France, Great Britain, Italy, the Netherlands, Portugal, Russia, Spain, Switzerland and the United States - an agreement which, for the first time, established an international health organization: the International Office of Public Hygiene. The Office was praised as the union between science and diplomacy, but also as the "fruit of the long and persistent European cooperation".
After the First World War, cooperation did not stop and a Health Organization was established in the framework of the League of Nations, which ended up coexisting with the International Office of Public Hygiene: although the competences of the two bodies were not clearly defined, the first dealt with various subjects - including epidemics, cancer, hygiene and nutrition - while the second mainly dealt with quarantine measures.
In January 1945, towards the end of the Second World War, the Office, which proved inadequate to deal with the difficult situation brought about by the conflict, came under the control of the United Nations Relief and Rehabilitation Administration (UNRRA), which had the task of assisting the countries - devastated by years of conflict - in health
matters; as is well known, after the war the League of Nations (and therefore its Health Organization) ceased to exist.
At the San Francisco Conference, which led to the establishment of the United Nations, the Brazilian delegation declared that "medicine is one of the foundations of peace", clarifying the common sentiment about the importance it should have in the new post-war order. The Statute signed in San Francisco clearly specifies that the UN should deal with cooperation in the field of health.
In 1946, the Economic and Social Council of the UN decided, therefore, to call a conference to address the issue of the establishment of an international organization for health in the framework of the United Nations, and the constitution of the World Health Organization was signed on July 22, 1946; the fast pace of the discussions was the proof of the importance given to cooperation in this area in the interests of peace and security - even though the Statute did not enter into force until 7 April 1948, due to a slowdown in preparatory work.
The statute sets out the principles on which the organization is founded:
- the enjoyment of the highest attainable standard of health is one of the fundamental rights of every human being;
- the health of all peoples is fundamental to the attainment of peace and security and depends on maximum collaboration between individuals and between States;
- The achievements of any State in the promotion and protection of health are of value for all;
- The unequal development, in different countries, of health promotion and control of diseases, in particular communicable diseases, is a common danger;
- Informed public opinion and active public cooperation are of the utmost importance in improving people's health;
- Governments are responsible for the health of their people, which can only be achieved by providing adequate health and social conditions.
Today, the WHO has 194 Member States and performs various functions to pursue its objectives and achieve those principles:
- It acts as a guide on key health issues and engages in partnerships where joint action is needed;
- outlines the research agenda and stimulates the creation, translation and dissemination of knowledge;
- sets norms and standards and promotes and monitors their implementation;
- defines evidence-based and ethical policy options;
- provides technical support, catalyses change and builds sustainable institutional capacity;
- monitors the health situation and assesses health trends.
Finally, in case of epidemics, it is the only organization that can declare a public health emergency of international concern.
 World Health Organization,The First Ten Years Of The World Health Organization, 1958, in http://apps.who.int/iris/bitst... pp. 3-4
 Ivi, p. 7
 Ivi, pp. 11-16
 Ivi, pp. 18-19
 Ivi, pp. 20-29
 Ivi, p. 31
 Ivi, p.38
 United Nations Charter, in
 World Health Organization,The First Ten Years Of The World Health Organization, cit., p.39
 Constitution of the World Health Organization
 World Health Organization: https://www.who.int/about/role/em
Council on Foreign Relations, The World Health Organization, https://www.cfr.org/backgrounder/world-health-organization