The Book of Leviticus has been described as the ‘first hygiene text’ based upon the observation that Leviticus contains a great deal of matter relating to two conditions. The first is צרעת translated in the Septuagint as λέπρα and confused in English translations with modern leprosy. The second, זוב was misused as a generic term for a whole spectrum of genital discharges. Apart from these, Leviticus contains nothing of a ‘medical’ nature. The question arises, as to whether these terms implied any sort of medical context or whether their only significance was as markers of ritual impurity to the priesthood. In Chapter 1 this question is developed and an hypothesis arrived at. A hermeneutic and methodology for the study are introduced and discussed. Chapter 2 is a review of the state of developing ‘medical practice’ in the Ancient Near East. Chapter 3 is concerned with the ideology of the levitical priesthood and their worldview in particular in respect of the establishment and operation of practice of ritual. Chapter 4 treats on the Levitical notion of impurity considered from both taxonomical and sociological standpoints and these approaches are discussed in the context of the present study. Chapters 5 and 6 each contain a detailed ‘medical exegesis’ of chapters 13 and 15 of Leviticus dealing with צרעת and .זוב Chapter 7 contains a similar treatment of the biblical notion of blemish and addresses the question of whether this was a mark of impurity like צרעת and .זוב In Chapter 8 embodies idea of contagion in the context of the ‘hygienic’ theme in Leviticus and the priests’ concern with what might imperil sacred objects. Chapter 9 employs context logometrical analysis in a detailed study of the word צרעת and whether there was, in Ancient Israel, any relationship, adverse or synergic between the activities of the priests in preserving purity, and early healthcare practice. Chapter 10 is a discussion of how צרעת has been seen from a theological perspective. While the exact nature of צרעת remains unknown, its biblical context — levitical and non levitical — is considered in relation to modern theories of the relationship of the impurity laws, sin and the wholeness↔ healthcare dynamic. Chapter 11 is a presentation of the conclusions that may be drawn from this study in respect of the wholeness↔ holiness paradigm posited in the hypothesis. It is concluded that there is no clear evidence to suggest that the priesthood saw צרעת and זוב in any terms commensurate with modern pathology and clinical medicine. Consequently it would be wrong to suppose, as many authors have, that in the levitical context, countermeasures to these conditions, though diagnostic, were hygienic in the modern, medical, — they were not, nor were they ever envisaged to be. That some of these measures subsequently found a significant place in preventive medicine appears to have been both fortuitous and fortunate.

La qualité de présentation d'une pomme de terre de consommation, Solanum tuberosum L., commercialisée en produit frais est devenue une exigence et un enjeu économique significatif dans les relations commerciales. Compte tenu du mode de reproduction par voie végétative de cette espèce, ces exigences sont également imposées au tubercule de semence. Organe de réserve et de propagation, le tubercule est produit sous terre, ce qui l'expose aux microorganismes telluriques et le rend potentiellement porteur d'altérations superficielles dont l'origine n'est pas encore clairement identifiée pour certaines d'entre elles. L'objectif de ce travail est de recenser et de caractériser ces altérations superficielles du tubercule et d'en déterminer les causes. Après l'établissement d'une nomenclature et d'une classification consensuelles des défauts observables sur tubercule, deux hypothèses ont été formulées et testées: (1) les défauts sont d'origine pathogène et/ou (2) ils résultent d'une réponse de la plante à des stress environnementaux. L'évaluation de la première hypothèse a mené à l'identification d'une grande diversité de microorganismes vivant à la surface des tubercules altérés. Leur pouvoir pathogène a été testé par une série de tests biologiques. Ceux-ci ont permis de reproduire les défauts sur des tubercules néoformés et de vérifier les postulats de Koch pour le champignon Rhizoctonia solani responsable de la formation de sclérotes. Pour bon nombre d'autres défauts visuels, aucune relation claire entre un microorganisme et une altération n'a pu être établie. Une étude de la structure des communautés microbiennes de la géocaulosphère de tubercules, altérés ou non, a démontré que les communautés fongiques et bactériennes se comportaient selon des dynamiques différentes au cours de la culture et en fonction de l'état sanitaire du tubercule de semence mais aucune relation de causalité n'a pu être mise en évidence. Il a par contre été noté une augmentation de la population de R. solani autour des tubercules altérés. La diversité des isolats d’origine française et européenne associés aux altérations des tubercules a donc été caractérisée. Elle révèle l'existence de relations phylogénétiques indépendantes de l'origine géographique et du cultivar hôte et suggère l'existence de d'événements génétiques fréquents et d'un brassage génétique entre les populations de R. solani. Le test de la seconde hypothèse a consisté à rechercher une implication potentielle de différents facteurs abiotiques dans la formation des altérations superficielles. L'analyse d'une enquête menée auprès d'agriculteurs a mis en évidence l'implication du pH, de certaines pratiques culturales, de la sensibilité de cultivars et de conditions météorologiques particulières dans l'occurrence de certains défauts. Ce travail a permis de clarifier la nomenclature des altérations, de confirmer l'implication de R. solani dans l'apparition de certaines d'entre elles et d'envisager de nouvelles hypothèses quant à la formation de défauts suite à une réponse de la plante à un stress environnemental. Ainsi, une voie a été ouverte vers la résolution de la problématique posée par toute une filière professionnelle, responsable de la mise en marché d'un produit frais de grande consommation, et répondant aux exigences du marché en matière de présentation, qualité culinaire et, mode de production respectueux de l'environnement. / The visual quality of fresh potatoes, Solanum tuberosum, became a dominant criterion and a significative economical issue in potato market. According the vegetative reproduction of this species, requirements for visual quality are also needed for potato seed tubers. As an organ for reserve and propagation, the tuber grows underground and is in contact with soil-borne microorganisms, making it potentially exposed to blemishes, for the majority of which the origin is still unclear.The objective of this work is to make an inventory of those tuber blemishes, to characterize them and determine their causes. After the establishment of consensual nomenclature and classification of the blemishes, two hypotheses were formulated: (1) blemishes are due to pathogenic attacks and/or (2) they result from a response of the plants to environmental stresses. The assessment of the first hypothesis allowed identifying a wide diversity of microorganisms living on the blemished tuber surface. Their pathogenicity was tested by several biological assays that allowed producing blemishes on progeny tubers and fulfilling the Koch's postulates for the fungus Rhizoctonia solani causing sclerotia. For many other blemishes no clear relationship was established between a microorganism and a blemish. A study of the microbial structure of the geocaulosphere of tubers blemished or not, showed that bacterial and fungal communities adopted different dynamics during the growing season and according to the sanitary status of the seed tuber, but no causality link could have been drawn. On the other hand, an increase of R. solani population around blemished tubers was observed. The diversity of strains of R. solani originating from France and from Europe and associated to the blemished tubers was characterized. The phylogenetic relationships between the strains were independent of the geographical origin and of the host cultivar, thus the existence of frequent genetic events and genetic mixing between the populations of R. solani was suggested. Concerning the potential implication of different abiotic factors, a survey conducted with farmers showed the implication of soil pH, some cultural practices, including the choice of the susceptible cultivars and meteorological conditions on the occurrence of some blemishes. This work made clear the blemish nomenclature, confirmed the implication of R. solani in the occurrence of some blemishes and suggested new hypotheses concerning the occurrence of blemishes as a plant response to a stressful environment. Thus, a path was opened toward the resolution of the issue asked by all the potato community, responsible for the marketing of a mass consumption fresh product and answering to market requirements related to visual and culinary qualities and to environmental friendly modes of production.