Original Strategy for Verbatim Collecting Knowledge from Mostly-Illiterate and Secretive Experts: West Africa Traditional Medicine's Case

80% of least developed countries populations rely on traditional medicine (TM). West Africa is not left outdone. Multilingualism is very manifest. Additionally, TM practitioners (TMP) commonly desire to keep secret their knowledge. Illiteracy affects the vast majority of TMP in this region. Thus, exchanges between practitioners for knowledge and experience sharing are severely hindered by multilingualism, illiteracy and secretiveness. The reliability and relevance question of the data and knowledge gathered from these practitioners is therefore raised. Conventional data collection methods are not operational in this context. Hence, we designed an original collection data method that we called back-and-forth, to overcome these difficulties. Such method allows us to obtain stable and verbatim collection from the TMP. Both sequential and recursive, it is applied to data collection during visits carried out for 110 practitioners in West Africa, with two to four visits per practitioner. 79 practitioners were finally included in the study project. The others 31 either did not adhere to the project or provided unstable knowledge. 13 diseases and 12 plants were collected, with the "plant cure disease" relations between them, as expressed by these 79 practitioners. Our second objective was to extend the domain ontology of west Africa TM, accurately ontoMEDTRAD, due to the emergence of three new concepts arising from the above. Face to climate change that may lead to some plants extinction, to update some old reference sources contents of TM, it has proved necessary to compare them with the opinions and knowledge collected from TMP.