Ecologie de la santé

Quand l'écologie pose son diagnostic. L'actualité nous le rappelle sans cesse : les maladies comme le paludisme, le Sida, ébola ou zika sont difficiles à combattre, et les maladies chroniques de type cancer, diabète ou maladies cardio-vasculaires toujours plus meurtrières. Pour la première fois de son histoire, l'humanité voit même son espérance de vie diminuer. Pour comprendre les raisons de cette crise sanitaire, l'écologie scientifique pose un autre regard sur la santé qui prend en considération les transformations de l'environnement et l'évolution de nos modes de vie. Cette nouvelle approche évolutive et écologique des problèmes de santé tente d'élucider les mécanismes en jeu dans la tr…

Occurrence of a sibling species complex within neotropical lymnaeids, snail intermediate hosts of fascioliasis.

The delimitation of cryptic species within the genus Lymnaea, which are the main vectors of fascioliasis, remains a topic of controversy. An analysis of genetic variability based on 12 enzyme loci revealed different fixed alleles at 9 loci between two sympatric samples of Lymnaea viatrix at the type locality in Lima, Peru. The absence of heterozygotes within this locality indicates the presence of isolated populations or cryptic species within L. viatrix. Significant genetic differences were also found between these two L. viatrix samples from Lima and other populations of L. viatrix in South America and in addition to species such as L. truncatula, L. cubensis and L. columella. Moreover, t…

Tracking zoonotic pathogens using blood-sucking flies as 'flying syringes'

About 60% of emerging infectious diseases in humans are of zoonotic origin. Their increasing number requires the development of new methods for early detection and monitoring of infectious agents in wildlife. Here, we investigated whether blood meals from hematophagous flies could be used to identify the infectious agents circulating in wild vertebrates. To this aim, 1230 blood-engorged flies were caught in the forests of Gabon. Identified blood meals (30%) were from 20 vertebrate species including mammals, birds and reptiles. Among them, 9% were infected by different extant malaria parasites among which some belonged to known parasite species, others to new parasite species or to parasite …

Isolation and characterization of microsatellite markers in the liver fluke (Fasciola hepatica)

PRIMER NOTE; International audience; Six microsatellite markers were isolated from Fasciola hepatica, a re-emerging parasite that causes important veterinary and public health problems. In a sample of 52 liver flukes from a region of hyperendemicity (Bolivian Altiplano), five microsatellite were polymorphic. Our results showed that liver flukes present important genetic variability, suggesting a preferential outcrossing reproduction mode for this hermaphroditic parasite.

Lack of molluscan host diversity and the transmission of an emerging parasitic disease in Bolivia.

Fasciolosis is a re-emerging parasitic disease that affects an increasing number of people in developing countries. The most severe endemic affects the Bolivian Altiplano, where the liver fluke (Fasciola hepatica) and its hermaphroditic snail host, Lymnaea truncatula, have been introduced from Europe. To achieve a better understanding of the epidemiological situation and the consequences of the colonization event of this invasive species, genetic analysis of Bolivian snail populations was needed. Here we compare the genetic diversity and population structure of snail samples from the Bolivian Altiplano with samples from the Old World at six polymorphic microsatellite loci. Whereas some vari…

Diversity and distribution of feather lice on Greater Flamingoes (Phoenicopterus ruber roseus) in the Camargue, southern France

Feather lice were collected from 2S0 chicks of the Greater Flamingo (Phoenicopterus ruber roseus Pallas) captured alive in the Camargue, southern France, in July 1997. Five louse species were identified: Colpocephalum heterosoma Piaget, Colpocephalum salimalii Clay and Trinoton femoratum Piaget of the family Menoponidae; Anaticola phoenicopteri (Coinde) and Anatoecus pygaspis (Nitzsch [in Giebel]) of the family Philopteridae. Our collecting results also show that there is body-site segregation among the several louse species inhabiting the same host individual.

Phylogeography and genetic divergence of some lymnaeid snails, intermediate hosts of human and animal fascioliasis with special reference to lymnaeids from the Bolivian Altiplano

Abstract A population genetic study using starch gel electrophoresis was performed on populations of several species of lymnaeid snails acting as intermediate hosts for Fasciola hepatica (Trematoda, Plathyhelminth). Lymnaea viatrix was collected in 16 sites from the Bolivian Northern Altiplano. L. cubensis were obtained in one site from Venezuela, one site from Guadeloupe, three sites from Cuba and one site from the Dominican Republic. L. truncatula were collected in one site from France, one from Portugal and one from Morocco. Multilocus enzyme electrophoresis (MEE) were determined for 282 snails at 18 loci. A complete monomorphism was encountered at each geographic site. However, among th…

Author response: Tracking zoonotic pathogens using blood-sucking flies as 'flying syringes'

Cancer: a disease at the crossroads of trade-offs

11 pages; International audience; Central to evolutionary theory is the idea that living organisms face phenotypic and/or genetic trade-offs when allocating resources to competing life-history demands, such as growth, survival, and reproduction. These trade-offs are increasingly considered to be crucial to further our understanding of cancer. First, evidences suggest that neoplastic cells, as any living entities subject to natural selection, are governed by trade-offs such as between survival and proliferation. Second, selection might also have shaped trade-offs at the organismal level, especially regarding protective mechanisms against cancer. Cancer can also emerge as a consequence of add…