De nombreux facteurs d'hA(c)tA(c)rogA(c)nA(c)itA(c) influent sur la dynamique globale des systA]mes A(c)pidA(c)miologiques (tranches d'A ge, structuration spatiale, etc). Ainsi, le concept de systA]me multi-patch offre un cadre appropriA(c) pour l'A(c)tude de l'influence spatiale dans la transmission de certaines maladies infectieuses. Nous nous intA(c)ressons dans cette thA]se A l'hA(c)tA(c)rogA(c)nA(c)itA(c) spatiale. Dans le cas de maladies A transmission directe, nous considA(c)rons un systA]me A(c)pidA(c)miologique multi-patch SIRS avec migration. Nous utilisons les mA(c)thodes...

After a survey about the historical development, the paper deals with the different institutions that are working for the realization of the old demand for a co-operation of scientists and technicians of different nations today. The abundance of the international organizations can be grouped in non public and public enterprises. Some among these have only to perform tasks of organization and administration and other concrete functions in scientific research or technical research and its industrial applications. Finally the or ganizations of world-wide membership differ from those whose...