Community Ecology of Rodents - Pathogens and habitat changes in Southeast Asia - CERoPath

Last update: 4 November 2016

Dynamics of communities of murine rodents, their parasites and pathogens in relation to major alterations of habitats in Cambodia, Thailand and Laos.

Project dates: 2008-2011

CERoPath aimed at analyzing the dynamics of communities of murine rodents, their parasites and pathogens in relation to major alterations of habitats along the Mekong River. In South-East Asia, rodents are hosts and vectors of several agents causing diseases in humans (including leptospirosis, scrub typhus, toxoplasmosis, viral hemorrhagic fevers) and in livestock (trypanosomiasis).

Context

Southeast Asia is a region characterized by a high biodiversity at risk, by major habitat changes due to strong economic development, and by the emergence of infectious diseases with pandemic potential. In this region, rodents are the reservoirs of several infectious and parasitic diseases in humans (viral haemorrhagic fever, scrub typhus, murine typhus, bartonellosis, plague, leptospirosis, helminthiasis) and livestock (trypanosomiasis).  

Objectives

The project based on the concepts and methods of evolutionary ecology aimed at:

  • Describing the diversity of rodents and their parasites and pathogens using morphological and molecular tools;
  • Characterizing the processes that contribute to patterns observed assemblages rodents-pests taking into account the environment, through the use of satellite imagery and geographic information systems, and evolutionary history of interacting species through the use of population genetics, molecular epidemiology and phylogenetics;
  • Building projections of changes in hosts-pathogens communities associated with habitat changes.

Activities and Results

Seven sites along the Mekong River, in Cambodia, Thailand and Laos were sampled according to a standardized protocol for estimating the diversity of rodents and their parasites, and their distribution according to a typology of habitats.

Nearly 3,000 rodents of twenty species were collected from these seven sites, plus four additional sites to improve the knowledge of their diversity and distribution and provide a unique collection of tissues and parasites.

The revisited phylogeny of Rattini contributed to a better delineation of reservoirs’ entities of human pathogens. A molecular barecoding tool has been developed to improve identification. The screening allowed the identification of new species or variants: hantavirus RNA viruses, bacteria, fungi and helminths and to position them phylogenetically. The results confirm the importance of rodents as reservoirs of many parasitic zoonoses and show the influence of geography, habitat or season on parasitic prevalence. The parasite diversity has a selective role on immunogenetic diversity and in trade-off investment between life history traits in rodents. The study sites are contrasted between sites with high rates of fragmentation of forests and sites showing an increase of urbanization at the expense of agricultural land.

The fine spatial description was used to characterize the environmental niche of rodents and the prevalence of their parasite infection. High local diversity in rodents, usually associated with complex habitats may reduce the risk of infection as hypothesized. However, other infectious agents appear to benefit from high rodent species diversity.
In addition to the production of a wide number of publications and scientific conferences, CERoPath has created an international network of researchers on zoonotic diseases associated with rodents in Asia. The website CERoPath with its virtual museum will be transformed into collaborative platform for this future network RoBoSEA.

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Partners

  • Irstea (Cemagref), the French National Research Institute of Science and Technology for Environment and Agriculture
  • AgroParisTech, the Paris Institute of Technology for Life, Food and Environmental Sciences
  • CNRS, the French National Center for Scientific Research
  • ISEM or the Institute of Evolutionary Sciences - Montpellier, France
  • Inra or the French National Institute for Agricultural Research  
  • CBGP, the Center for Biology and Management of Populations
  • IRD, the French Research Institute for Development
  • SupAgro, the Institute for Higher Education in Agricultural Sciences, France
  • BDEEP, Biology and Diversity of Emerging Eukaryotic Pathogens Laboratory, Lille, France
  • Inserm, the French National Institute for Health and Medical Research
  • NAFRI, National Agriculture and Forestry Research Institute, Vientiane, Lao PDR
  • TISTR, Thailand Institute of Scientific and Technological Research, Thailand

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Last update: 4 November 2016