9 research outputs found
Relationship between Transmission Intensity and Incidence of Dengue Hemorrhagic Fever in Thailand
An infection with dengue virus may lead to dengue hemorrhagic fever (DHF), a dangerous illness. There is no approved vaccine for this most prevalent mosquito-borne virus, which infects tens of millions (or more) people annually. Therefore, health authorities have been putting an emphasis on reduction of vector mosquitoes, genus Aedes. However, a new mathematical hypothesis predicted, quite paradoxically, that reducing Aedes mosquitoes in highly endemic countries may “increase” the incidence of DHF. To test this hypothesis based upon actual data, we compared DHF incidence collected from each of 1,000 districts in Thailand to data of Aedes abundance, which was obtained by surveying one million households. This analysis showed that reducing Aedes abundance from the highest level in Thailand to a moderate level would increase the incidence by more than 40%. In addition, we developed computer simulation software based upon the above hypothesis. The simulation predicted that epidemiological studies should be continued for a very long duration, preferably over a decade, to clearly detect such a paradoxical relationship between Aedes abundance and incidence of DHF. Such long-term studies are necessary, especially because tremendous efforts and resources have been (and perhaps will be) spent on combating Aedes
Première observation d’un comportement de Leaf Swallowing chez des chimpanzés vivant en captivité à la Réserve Africaine de Sigean, France
Le Leaf Swallowing (LS) consiste en une consommation atypiquement lente de feuilles souvent rugueuses, qui sont roulées et avalées, une par une, sans mastication. Cette consommation favoriserait l’expulsion de parasites intestinaux et/ou augmenterait le transit intestinal. Nous rendons compte ici de l’observation de ce type de comportement dans une population de chimpanzés (Pan troglodytes) vivant en captivité à la Réserve Africaine de Sigean (RAS), en France. Nous avons proposé à neufs chimpanzés des feuilles lisses et non rugueuses de platane (Platanus hispanica) et des feuilles rugueuses et poilues de mûrier noir (Morus nigra). Cinq des chimpanzés ont réalisé un comportement de LS avec les feuilles rugueuses de mûrier noir. Ces individus étaient présumés naïfs pour le LS car ce comportement n’avait jamais été observé dans cette population avant ladite étude. L’apparition ici du comportement de LS chez des individus naïfs appuie la théorie d’une prédisposition à la réalisation de LS avec des feuilles rugueuses, probablement par apprentissage individuel. Nous relevons aussi le rôle important de l’apprentissage social (facilitation et imitation) dans la diffusion de ce comportement au sein du groupe car nous avons observé des modifications du comportement face aux feuilles de mûrier noir, passant du rejet ou d’une consommation de type alimentaire, à du LS après observation d’un congénère démonstrateur de LS. L’observation d’une consommation en LS dans cette population de chimpanzés sains (non parasités et sans inconfort intestinal notable) soutient l’hypothèse que le LS provient d’un comportement d’alimentation opportuniste des primates dans la nature et non d’une connaissance innée de la propriété thérapeutique de cette forme de consommation. Le LS serait simplement une réaction spontanée face à une rugosité peu familière des feuilles. L’apparition de LS avec des feuilles de M. nigra, alors que des feuilles de cette même espèce n’ont pas donné lieu à du LS dans une précédente étude, nous permet d’infirmer l’hypothèse de l’existence d’une rugosité seuil, commune à tous les chimpanzés, qui déclencherait de manière systématique un comportement de LS.Leaf Swallowing (LS) is an atypically slow consumption of often rough leaves, which are rolled and swallowed, one by one, without chewing. This method seems to promote the expulsion of intestinal parasites and/or increase intestinal transit. We report observations of this type of behaviour in a population of chimpanzees (Pan troglodytes) living in captivity at the African reserve of Sigean (RAS), in France. Nine chimpanzees were provided with smooth, non-rough leaves of a plane tree (Platanus hispanica) and with rough, hispid leaves of a black mulberry (Morus nigra). All these individuals were presumed naive to LS because this behaviour had never been observed in this population before the study. This observation of LS behavior in naive chimpanzees supports the theory of a predisposition to the realization of LS with rough leaves, probably by individual learning. We also note the important role of social learning (facilitation and imitation) in the LS behaviour spread within the group. Indeed, some chimpanzees which initially rejected or chewed black mulberry leaves, then fold and swallow them (LS) after observing a congener demonstrator. Observation of LS in this healthy chimpanzee population (parasite-free, no noticeable intestinal discomfort) supports the hypothesis that LS originates from an opportunistic feeding behavior of primates in nature and not from an innate knowledge of the therapeutic property of this form of consumption. LS may simply be a spontaneous reaction to an unfamiliar leaf roughness. In this study, LS occurred with M. Nigra leaves, while this kind of behaviour was not observed with the leaves of the same species in a previous study. This allows us to refute the hypothesis of the existence of a roughness threshold, common to all chimpanzees, which would systematically trigger LS behavior
Some Jellyfish Like It Hot!
When you go to the beach, it might seem like there are more jellyfish every summer. Is this true? We study the barrel jellyfish, which lives in the Mediterranean and Black Seas. Since the end of the XIX century, many scientists and interested members of the public have been recording the sightings of this jellyfish along the coasts. We collected this information to see whether jellyfish numbers are increasing with the warming of the ocean waters. We found that, due to the warming of the sea caused by climate change, the barrel jellyfish are appearing earlier in the year, and there are greater numbers of barrel jellyfish in some regions now compared with years past. Although other factors, such as food, predators, or habitat changes may also affect marine species, our results indicate that ocean warming could have direct effects on living organisms, changing the functioning of marine ecosystems
Mechanistic simulation models in macroecology and biogeography: state-of-art and prospects
Impact of the first wave of COVID-19 epidemy on the surgical management of sigmoid diverticular disease in France: National French retrospective study
International audienceObjective: To analyze the surgical management of sigmoid diverticular disease (SDD) before, during, and after the first containment rules (CR) for the first wave of COVID-19.Methods: From the French Surgical Association multicenter series, this study included all patients operated on between January 2018 and September 2021. Three groups were compared: A (before CR period: 01/01/18-03/16/20), B (CR period: 03/17/20-05/03/20), and C (post CR period: 05/04/20-09/30/21).Results: A total of 1965 patients (A n = 1517, B n = 52, C n = 396) were included. The A group had significantly more previous SDD compared to the two other groups (p = 0.007), especially complicated (p = 0.0004). The rate of peritonitis was significantly higher in the B (46.1%) and C (38.4%) groups compared to the A group (31.7%) (p = 0.034 and p = 0.014). As regards surgical treatment, Hartmann's procedure was more often performed in the B group (44.2%, vs A 25.5% and C 26.8%, p = 0.01). Mortality at 90 days was significantly higher in the B group (9.6%, vs A 4% and C 6.3%, p = 0.034). This difference was also significant between the A and B groups (p = 0.048), as well as between the A and C groups (p = 0.05). There was no significant difference between the three groups in terms of postoperative morbidity.Conclusion: This study shows that the management of SDD was impacted by COVID-19 at CR, but also after and until September 2021, both on the initial clinical presentation and on postoperative mortality