Ana Rivero            Site web

MiVEGEC "Maladies infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle", IRD, Montpellier

Research interests

I work on the evolution of mosquito-Plasmodium interactions. Under natural conditions of transmission intensity, and even under the best laboratory conditions, malaria parasite loads in mosquitoes show a greater variability than that expected by standard statistical models which assume random parasite distributions. Similarly, impact of the parasite on the fitness of the mosquito can vary from virulent to relatively avirulent. My group has been using the avian malaria system to identify the genetic and environmental sources of heterogeneity in these two key parameters for malaria transmission. 

Avian malaria parasites share a distant common ancestor with human malaria parasites and have historically played an important role as models in the study of human malaria. Avian malaria is a unique animal model to understand the ecology and evolution of the disease both in the laboratory and in the field. It is much more prevalent (in some areas up to 80% of birds are infected) diverse (more than 600 mitochondrial cytochrome b sequences described thus far) and widespread (it is present in all continents except Antarctica) than any other known vertebrate malaria.

Our initial focus was on mosquito-driven heterogeneity. We have worked on the role of the genetic background (insecticide resistance/susceptibility), and condition (nutrition, age) of the mosquitoes, the coinfection with bacterial endosymbionts (Wolbachia), or the infectious status of previous generations (transgenerationnal immune priming). We have also worked on the ability of Plasmodium to both manipulate mosquito behaviour and plastically adjust its within-bird transmission strategies in response to the availability of mosquitoes to maximize its own transmission. We are currently focusing on the role of parasite and host variability in shaping Plasmodium transmission, a crucial piece of the transmission puzzle for which there is still insufficient information in the malaria literature.

Thierry Wirth        Site web

Muséeum d'Histoire Naturelle de Paris, Institut de Systématique, Évolution et Biodiversité.

Research interests

Evolutionary History and Origin of Major Human Diseases
I am characterizing and measuring the processes that determine bacterial populations, in particular the evolution of sex and virulence in Escherichia coli. I am also investigating the coalescent and origin of major human disease agents (Yersinia pestis and Mycobacterium tuberculosis). Another line of research is the use of bacterial genetics for tracking the population genetics of their hosts or symbionts (i.e. Helicobacter pylori as a marker for human migrations).

Coevolution of Lassa Virus and its Rat Reservoir
Lassa virus (LASV), a biosafety level 4 agent is an endemic hemorrhagic fever virus of West Africa which causes up to 100.000 cases of Lassa fever (LF) and occurs sporadically in outbreaks with high mortality. We investigated concomitantly the population structure, evolution and demography of LASV and its natural reservoir, the rat Mastomys natalensis. This is, to our knowledge, the first report of an impact of conflict situations on the phylogeography and demography of a virus, which is the cause of an emerging infectious disease.

The Evolution and Spread of the Leishmania donovani Complex
In the New World, Leishmania infantum (syn. L. chagasi) is the principal causative agent of visceral leishmaniasis. There are two contradictory hypotheses about its origin : (1) the recent import of L. infantum from the Old World and synonymy of L. chagasi and L. infantum or (2) an indigenous origin of the parasite and a distinct taxonomic rank for the New World parasite. We are currently investigating the evolutionary history, origin and spread of this parasite using Bayesian statistics and a global collection of strains.

Atlantic Eels Population Genetics and Host-Parasite Coevolution
Research being performed in the group related to the population structure of the endangered Atlantic eels. We recently investigated the population structure of an invasive parasite, the nematode Anguillicola crassus that came from Asia to Europe some 30 years ago. The molecular coevolution of the pathogens and the host at the Major Histocompatibility Class II genes. A primary aim of this research is to understand short term adaptation to major selective pressure and the detrimental effects of exotic parasites on naive host populations.