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Christophe DIAGNE
Email: christophe.diagne(at)
Position: postdoc, IRD
Topic: Parasite community ecology of native and invasive rodents in environmental change context at North Senegal
Funding: IRD
Dates : February 1st, 2016 – January 31st, 2018

Numerous studies suggest that environmental change-related introduction of exotic species may impact the circulation of both native and non-native parasites in colonized areas. Newly introduced species may be a source of novel parasites, and/or influence the transmission probability of local parasites. As a result of changes in host biodiversity and density, such probability may either increase (‘amplification’ hypothesis) or decrease (‘dilution’ hypothesis) depending on the competence of introduced host to maintain and transmit the parasite. Given that rodents are major reservoirs of human, pet and livestock pathogens, such variation in relationships between host biodiversity and parasite circulation can have important consequences for public health issues.

Gerbillus nigeriae – biological indicator of climatic and environmental changes in Sahel – currently invading Senegal (West Africa) provides unique opportunities to perform comparative study in a well-defined spatio-temporal context on the host biodiversity – parasite circulation issues. G. nigeriae is considered as one of the most important invasive species in the Sahel, both in terms of the rate of geographic spread and negative impacts. Appeared in Northern Senegal in the mid-1990s probably since Mauritania, G. nigeriae benefitted from both habitat increase aridity (decrease of rainfalls, depletion of groud water resources, southward shift of rainfall isolines) and anthropisation (logging, soil erosion, overgrazing) to expand its distribution southwards, becoming one of the dominant species in most natural and agricultural habitats at North Senegal.

Based on longitudinal surveys carried out since 2009 on rodent communities – and their parasites – from several localities, our study aims at analysing the relationships between spatio-temporal variations in parasite community structure (gastrointestinal helminths, bacteria, viruses and/or protozoa), environmental characteristics and relative abundance/density of native and invasive rodent host species in Senegalese Sahelian ecosystems. This work will allow detecting and deciphering pathogens related to public health issues.