Topography and land cover of watersheds predicts the distribution of the environmental pathogen Mycobacterium ulcerans in aquatic insects.
BACKGROUND
An understanding of the factors driving the distribution of pathogens is useful in preventing disease. Often we achieve this understanding at a local microhabitat scale; however the larger scale processes are often neglected. This can result in misleading inferences about the distribution of the pathogen, inhibiting our ability to manage the disease. One such disease is Buruli ulcer, an emerging neglected tropical disease afflicting many thousands in Africa, caused by the environmental pathogen Mycobacterium ulcerans. Herein, we aim to describe the larger scale landscape process describing the distribution of M. ulcerans.


METHODS
Following extensive sampling of the community of aquatic macroinvertebrates in Cameroon, we select the 5 dominant insect Orders, and conduct an ecological niche model to describe how the distribution of M. ulcerans positive insects changes according to land cover and topography. We then explore the generalizability of the results by testing them against an independent dataset collected in a second endemic region, French Guiana.


RESULTS
We find that the distribution of the bacterium in Cameroon is accurately described by the land cover and topography of the watershed, that there are notable seasonal differences in distribution, and that the Cameroon model does not predict the distribution of M. ulcerans in French Guiana.


CONCLUSIONS
Future studies of M. ulcerans would benefit from consideration of local structure of the local stream network in future sampling, and further work is needed on the reasons for notable differences in the distribution of this species from one region to another. This work represents a first step in the identification of large-scale environmental drivers of this species, for the purposes of disease risk mapping.
Unité mixte de recherche (UMR) Maladies Infectieuses et Vecteurs: Écologie, Génétique, Evolution, et Contrôle (MIVEGEC) IRD-CNRS-Universities of Montpellier I and II, Centre IRD de Montpellier, Montpellier, France; UMR Territoires, Environnement, Télédétection et Information Spatiale (TETIS) CIRAD, Montpellier, France; Unité d'Epidémiologie de Maladies Emergentes, Institut Pasteur, Paris, France.
Kevin
K
Carolan
Unité mixte de recherche (UMR) Maladies Infectieuses et Vecteurs: Écologie, Génétique, Evolution, et Contrôle (MIVEGEC) IRD-CNRS-Universities of Montpellier I and II, Centre IRD de Montpellier, Montpellier, France; Ecole des Hautes Etudes en Santé Publique, Rennes, France.
Andres
A
Garchitorena
Unité mixte de recherche (UMR) Maladies Infectieuses et Vecteurs: Écologie, Génétique, Evolution, et Contrôle (MIVEGEC) IRD-CNRS-Universities of Montpellier I and II, Centre IRD de Montpellier, Montpellier, France; Centre de Synthèse et d'Analyse sur la Biodiversité -CESAB. Bâtiment Henri Poincaré, Domaine du Petit Arbois. Aix-en-Provence, France.
Gabriel E
GE
García-Peña
Unité mixte de recherche (UMR) Maladies Infectieuses et Vecteurs: Écologie, Génétique, Evolution, et Contrôle (MIVEGEC) IRD-CNRS-Universities of Montpellier I and II, Centre IRD de Montpellier, Montpellier, France; Bournemouth University, School of Applied Sciences, Dorset, United Kingdom.
Aaron
A
Morris
Unité d'Epidémiologie de Maladies Emergentes, Institut Pasteur, Paris, France; Service d'épidémiologie et de santé publique, Centre Pasteur du Cameroun, Réseau International des Instituts Pasteur, Yaoundé, Cameroun.
Jordi
J
Landier
Unité d'Epidémiologie de Maladies Emergentes, Institut Pasteur, Paris, France; Chaire Santé et Développement, Conservatoire National des Arts et Métiers, Paris, France.
Arnaud
A
Fontanet
Institut de Recherche pour le Développement (IRD), UR 072, Laboratoire Evolution, Génomes et Spéciation, UPR 9034, Centre National de la Recherche Scientifique (CNRS), Gif sur Yvette, France et Université Paris-Sud 11, Orsay, France.
Philippe
P
Le Gall
Service d'épidémiologie et de santé publique, Centre Pasteur du Cameroun, Réseau International des Instituts Pasteur, Yaoundé, Cameroun; UMR 912 - SESSTIM - INSERM/IRD/Aix-Marseille Université Faculté de Médecine - 27, Marseille, France.
Gaëtan
G
Texier
ATOMycA, Inserm Avenir Team, CRCNA, Inserm U892, 6299 CNRS and LUNAM, Angers, France.
Laurent
L
Marsollier
Unité mixte de recherche (UMR) Maladies Infectieuses et Vecteurs: Écologie, Génétique, Evolution, et Contrôle (MIVEGEC) IRD-CNRS-Universities of Montpellier I and II, Centre IRD de Montpellier, Montpellier, France; Bournemouth University, School of Applied Sciences, Dorset, United Kingdom; UMR 207 BOREA IRD-MNHN-Université Pierre et Marie Curie, Muséum National d'Histoire Naturelle, Paris, France.
Rodolphe E
RE
Gozlan
Service de Mycobactériologie, Centre Pasteur du Cameroun, Réseau International des Instituts Pasteur, Yaoundé, Cameroun.
Sara
S
Eyangoh
UMR Territoires, Environnement, Télédétection et Information Spatiale (TETIS) CIRAD, Montpellier, France.
Danny
D
Lo Seen
Unité mixte de recherche (UMR) Maladies Infectieuses et Vecteurs: Écologie, Génétique, Evolution, et Contrôle (MIVEGEC) IRD-CNRS-Universities of Montpellier I and II, Centre IRD de Montpellier, Montpellier, France; Ecole des Hautes Etudes en Santé Publique, Rennes, France.
Jean-Francois
JF
Guégan
D000818:Animals; D054312:Buruli Ulcer / Q000453:epidemiology* / Q000635:transmission; D002163:Cameroon / Q000453:epidemiology; D004197:Disease Reservoirs / Q000382:microbiology*; D004777:Environment; D062305:Geographic Mapping; D007313:Insecta / Q000382:microbiology*; D019911:Mycobacterium ulcerans / Q000235:genetics / Q000302:isolation & purification*