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A cross-sectional study was conducted on bovine brucellosis in a sample of 173 medium/small-scale cattle farmers in a tropical region of Ecuador. A total of 173 milk tank samples were collected and analyzed through an indirect ELISA. A survey was also applied to each farm to collect information on herd management, evaluate the level of knowledge about the disease and estimate the risk that bovine brucellosis on those farms could represent for public health. The apparent prevalence among farms was 11.5% (95% CI: 6.7%-16.2%). The medium farms had a prevalence significantly higher (23.8%,95% CI: 10.9%-36.6%, p<0:0001) than the small farms (7.6%, 95% CI: 4.5%-9%). Two multivariable analysis were conducted to identify risk factors associated with bovine brucellosis or reproductive disorders. Medium farms had 3.7 more odds to be infected than the small farms (OR: 3.7, 95% CI: 1.39-9.84, p = 0:008). Incineration/burial of abortion material was identified as a protective factor (OR: 0.4, 95% CI: 0.14-0.98, p = 0:04). Farm size and brucellosis were identified as risk factors for the occurrence of reproductive disorders. Only 25% of the farmers were aware of bovine brucellosis. Unpasteurized curdled milk was regularly consumed and marketed on 112 farms of which 14 were positive for bovine brucellosis. Highly at-risk practices, such as manipulation of aborted fetuses were also reported. These results indicate that there is a need to develop public health education programs targeted at medium/small-scale farmers in Ecuador. [ABSTRACT FROM AUTHOR]

On étudie l'évolution des propriétés optiques de trois kérogènes peu évolués au cours de leur pyrolyse sous azote en programmation de température. Le premier appartient à une série lacustre (Green River Shales), le second à une série marine (Toarcien du bassin de Paris), le troisième à une série deltaïque (Crétacé du Cameroun). On constate la ressemblance de l'évolution artificielle avec la catagenèse (évolution accompagnant l'enfouissement des sédiments). On observe dans les deux premiers kérogènes l'existence de particules ressemblant à de la vitrinite, mais dont les propriétés optiques évoluent différemment. On incite en conséquence à une grande prudence dans l'utilisati n du pouvoir réflecteur de telles particules pour localiser dans les séries lacustres et marines la zone de formation du pétrole. On note l'intérêt de mesurer le pour réflecteur de la grande masse du kérogène et de mettre son évolution en relation avec celle des autres propriétés physiques. This article examines the evolution of the optical properties of three immature kerogens during their pyrolysis in nitrogen ut programmed temperature. The first kerogen comes from a lacustrine series (Green River Shales), the second from a marine series (Tourcian from the Paris Basin), and the third from a deltaic series (Cretaceous from Cameroon). There is a resemblance in their artificial evolution with catagenesis (evolution accompanying the burial of the sédiments). The first two kerogens cari be seen to contain particles resembling vitrinite, although with optical properties which evolve differently. Therefore, great cure must be taken in using the reflecting power of such particules ta situate the petroleum forming zone in lacustrine and marines séries. It is important ta measure the reflecting power of the general mass of the kerogen and to compare its evolution with that of the other physical properties.

La pyrolyse Rock-Eval et la chromatographie des effluents de pyrolyse de charbons de tous âges géologiques montrent qu'ils produisent jusqu'à 20 % de leur poids d'hydrocarbures. Ces hydrocarbures sont surtout des hydrocarbures liquides (C+5) jusqu'à un rang correspondant à environ 1,5 % de pouvoir réflecteur de la vitrinite. C'est pourquoi des quantités appréciables d'huile devraient être formées au cours de la houillification de la plupart des charbons, quel que soit l'âge de leur dépôt. L'absence quasi générale de gisements d'huile dans les séries à charbons paléozoïques serait donc due à des facteurs géologiques et non des caractères géochimiques particuliers. Dans ces séries anciennes, l'huile formée a probablement été dissipée par migration au cours des cycles sédimentaires successifs. A rang égal, la variabilité des quantités et des distributions des hydrocarbures formés par pyrolyse est aussi grande pour les charbons que pour les autres types de matière organique. Rock-Eval pyrolysis and the chromatography of pyrolysis effluents from coals of all geological ages show that such coals produce up to 20% of their weight in hydrocarbons. These hydrocarbons are mainly liquid hydrocarbons (C+5) up to a rank corresponding to about 1,5% of the reflecting power of vitrinite. This is why appreciable quantities of oil should be formed during the coalification of most coals, no matter what their age of deposition may be. The quasi general absence of oil accumulations in Paleozoic coal series should thus be due to geological factors and not to specific geochemical features. The oil formed in such ancient series was probably dissipated by migration during successive sedimentary cycles. For equal rank, the variability of the amounts and distributions of hydrocarbons formed by pyrolysis is just as great for coals as for other types of organic matter.