Dynamics of host-reservoir transmission of Ebola with spillover potential to humans

Ebola virus disease (EVD) is a zoonotic borne disease (i.e. disease that is spread from animals to people). Therefore human beings can be infected through direct contact with an infected animal (fruit-eating bat or great ape). It has been demonstrated that fruit-eating bats of pteropodidae family are potential reservoir of EVD. Moreover, it has been biologically shown that fruit-eating bats do not die due to EVD and bear the Ebola viruses lifelong. We develop in this paper, a mathematical model to assess the impact of the reservoir on the dynamics of EVD. Our model couples a bat-to-bat model with a human-to-human model and the indirect environmental contamination through a spillover process (i.e. process by which a zoonotic pathogen moves (regardless of transmission mode) from an animal host (or environmental reservoir) to a human host) from bats to humans. The sub-models and the coupled models exhibit each a threshold behavior with the corresponding basic reproduction numbers being the bifurcation parameters. Existence of equilibria, their global stability are established by combining monotone operator theory, Lyapunov-LaSalle techniques and graph theory. Control strategies are assessed by using the target reproduction numbers. The efforts required to control EVD are assessed as well through S-control. The spillover event is shown to be highly detrimental to EVD by allowing the disease to switch from bats to humans even though the disease was not initially endemic in the human population. Precisely, we show that the spillover phenomenon contributes to speed up the disease outbreak. This suggests that the manipulation and consumption of fruit-bats play an important role in sustaining EVD in a given environment

Régénération Naturelle Assistée Du Teck (Tectona Grandis L. F.) Dans La Forêt Classée De La Lama Au Bénin

La régénération naturelle assistée, technique utilisée pour favoriser le développement du potentiel adventif et du potentiel séminal des arbres, est un mode de reproduction adopté de nos jours pour renouveler et pérenniser les formations forestières. La présente étude a été réalisée dans les plantations de la forêt classée de la Lama, situées entre 6°55' et 7°00' de latitude Nord et entre 2°4' et 2°12' de longitude Est. Elle vise à proposer une technique de régénération naturelle assistée peu coûteuse adaptée aux peuplements de teck installés sur des vertisols hydromorphes. Trois méthodes de régénérations naturelles assistées ont été testées sur quatre types de sols (vertisol argilosableux, vertisol argileux, vertisol argilo-calcaire et vertisols argilo-calcaire superficiel). Pour chaque traitement sur chaque type de sol, deux placeaux carrées de 100 m2 ont été matérialisés avec chacun huit placettes de 4 m2. La régénération a été inventoriée dans chaque placette et des relevés ont été effectués par rapport au nombre, hauteur et circonférence au collet des jeunes plants. L’évaluation des coûts de la méthode a été réalisée grâce à une comptabilité analytique régulière prenant en compte toutes les dépenses d’installation et de maintenance des parcelles expérimentales. La densité, hauteur et circonférence au collet varient significativement en fonction des types de sol. Toutefois, les plants sont plus développés en hauteur et en circonférence au collet dans les interlignes que sur les lignes. La régénération sur sol non travaillé est le moins coûteuse et donc celui à recommander aux gestionnaires des teckeraies de la Lama. Assisted natural regeneration is a technique used to promote the development of the seminal potential of trees. Actually, it is a mode of reproduction adopted to renew and sustain the forests. This study was carried out in the plantations of the Lama reserve (between 6° 55' and 7° 00' north and between 2° 4'and 2° 12' east). It aims to propose an inexpensive assisted natural regeneration method adapted to teak stands installed on hydromorphic vertisols. Three assisted natural regeneration methods were tested on four soil types ((clay-sandy vertisol, clay vertisol, clay-limestone vertisol, and superficial clay-limestone vertisols). For each treatment about each type of soil, two square plots (100 m2) were materialized with eight plots of 4 m2 each one. Regeneration was inventoried in each plot and data are collected about number, height, and circumference at the neck of seeding. The production costs were assessed through regular cost accounting taking into account all the installation and maintenance expenses of the experimental plots. From the results, density, height, and collar circumference vary significantly with soil types. However, the seedlings are more developed in height and circumference at the collar in the interlinings than on the lines. Regeneration on unworked soil is the least expensive and therefore the one to recommend to managers of teak plantations of the Lama