At the end of the nineteenth century, as colonisation progresses, physicians realise the magnitude of the problems they are faced with and make an effort to ameliorate the health services for local populations. This medical activity is rapidly institutionalised to become Medical Assistance for the Indigenous People (A.M.I. - Assistance médicale indigène).

Following the ideas of the time and with the means at their disposal, these first physicians only intend to initiate a unique health system and they try to increase the number of health centres in the hope that, one day, the network would cover the whole of the colonised territories. So hospitals are built in the principal towns, with local laboratories and, later, blood-transfusion centres.

In all the principal towns, even the smallest, particular attention is paid to public hygiene. But, the task being immense, it soon becomes evident that grave diseases and epidemics can be held at bay only by controlling the whole population and by going out to contact them; whence the creation of the Great Endemics Service (service des grandes endémies). This service survives for some time after the granting of independence under the name of "Organisation de coopération et de coordination dans la lutte contre les grandes endémies" (OCCGE) in West Africa and "Organisation de coordination dans la lutte contre les grandes endémies en Afrique centrale" (OCEAC) in Central Africa.