League of Nations
With the founding of the League of Nations in 1919, the Office international d'hygiène publique (OIHP) was supposed to be incorporated into the League, however, that did not happen. The United States, which was a member of OIHP but did not join the League, refused to approve the merger. This led to two large international organizations frequently cooperating and sharing information but nevertheless functioning separately. In 1926, more than 50 nations met for the 13th International Sanitary Conference in Paris, the largest such meeting to date. The resulting 1926 International Sanitary Convention was the first truly global approach to health and sanitation, laying out rules and requirements for such things as quarantines and epidemic control. The increasing proliferation of airplanes also led to a need for a specific convention addressing air travel: the International Sanitary Convention for Aerial Navigation, which came into force in 1933.