Plague Circulation and Population Genetics of the Reservoir Rattus rattus: The Influence of Topographic Relief on the Distribution of the Disease within the Madagascan Focus

• Published in: PLoS Neglected Tropical Diseases
• Main Authors: Brouat, Carine, Rahelinirina, Soanandrasana, Loiseau, Anne, Rahalison, Lila, Rajerison, Minoariso, Laffly, Dominique, Handschumacher, Pascal, Duplantier, Jean-Marc
• Format: Text
• Language: English
• Published: Public Library of Science 2013
• Subjects: Research Article; Rattus rattus
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3674990; http://www.ncbi.nlm.nih.gov/pubmed/23755317; https://doi.org/10.1371/journal.pntd.0002266

Plague (Yersinia pestis infection) is a highly virulent disease occurring in many natural ecosystems. One of the major plague foci is Madagascar, where plague has been confined principally to the central highlands since the 1920s. Despite the high prevalence of plague, its ecology has scarcely been studied. Previous studies of plague seroprevalence in humans have suggested that the disease spreads unevenly across landscapes, possibly due to the relief. Plague is primarily a disease of rodents. We therefore investigated the relationship between its distribution and the population genetic structure of its main reservoir, the black rat, Rattus rattus. We used serological and microsatellite-based population genetic analyses to compare four geographic areas of the plague focus (two mountainous areas, two plateaus). Rat populations had a more marked genetic structure in areas of greater relief. The heterogeneous distribution of plague in the highlands may be related to the population genetic structure of its reservoir, but our results suggest also a role for humans in the dispersion of the disease.