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Centre d’Etude de la Biodiversité Amazonienne - © 2012
Jean-François Guégan3
Both complex temporal signals and
deforestation/land-use changes drive the
emergence of human water-borne disease
Jean-François Guégan, Aaron L. Morris, Demetra Andreou,
Laurent Marsollier, Jérémie Babonneau, Daniel Sanhueza,
Marie Le Croller, Kevin Carolan, Elsa Canard
and Rodolphe E.Gozlan
Laboratory of Excellence CEBA
E-mails: jean-francois.guegan@ird.fr
rudy.gozlan@ird.fr
U.N. Climate Change Conference COP-21, Paris, July 2015
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Cases of Buruli ulcer from 1969 to 2012 per 100,000 people, the dotted
line represents the increasing human population living in French Guiana
Time series of BU cases in F. Guiana (grey bars)
Human population growth in FG (blue line)
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Work done within the meta-
programme BIOHOPSYS
from LabEx CEBA
Centre d’Etude de la Biodiversité Amazonienne - © 2012
PhD students enrolled to spend one-year and a
half in hard environments
Aaron Morris, PhD student
In French Guiana >2015: Veterinary Imperial College, London
Andrés Garchitorena, PhD student
in Cameroon >2015: Harvard School of Public Health
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Population dynamics of
Buruli ulcer cases in
French Guiana
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Buruli cases and rainfall in French Guiana
occurring on a long (i.e., several years)
Highest number of BU cases during periods of low yearly rainfall
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Buruli cases and rainfall in French Guiana
occurring on short (i.e., seasonal) temporal scale
2nd temporal scale suggests cases peak during periods of high
levels in rainfall variation
Centre d’Etude de la Biodiversité Amazonienne - © 2012
BU outbreaks can be triggered by combinations,
i.e. annual and long-term, of rainfall patterns
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Mycobacterium ulcerans
persistence and dynamics in
aquatic systems
Centre d’Etude de la Biodiversité Amazonienne - © 2012
• 23 surveyed sites
• Gradient of land-use
(urban, agricultural, perturbed forest,
pristine)
• Sites were sampled for aquatic
invertebrates, fish and other small
aquatic vertebrates
• Each invertebrate/vertebrate was
measured in length and identifies at
the family level or species level
• qPCR analysis for MU
• Stable isotope analysis δ13C / δ15N
• Positive sites for MU highly
stagnant, shallow water bodies, with
high levels of M. arborescens
“Moucou-moucou” plants
First detection of M. ulcerans DNA from
environmental samples in South America
Morris A.L. et al. (2013) First detection of Mycobacterium ulcerans in
environmental samples from South America. PLoS NTD 8 | Issue 1 | e2660
Centre d’Etude de la Biodiversité Amazonienne - © 2012
% in
fect
ed s
amp
les
MU is near everywhere, it depends if you look at or not!
Everywhere Somewhere
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Characterisation of functional biodiversity in
French Guiana
• Over 4,000 invertebrates and fish were collected,
• 90 different taxa were identified,
• 44 taxa tested positive for MU (both IS2404 &KR),
• Bacterial concentrations from 6 to 7,837 bacilli/mg of organism,
roughly the same as in Cameroon (Ref. Garchitorena’s work)
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Characterisation of functional biodiversity in
French Guiana
10 functional groups
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Characterisation of functional biodiversity in
French Guiana
M. ulcerans
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Studying freshwater food webs and MU
• Landscape data was extracted from
2 maps
- CORINE Land Cover 2006
(25m resolution)
- Hansen deforestation maps,
(30m resolution)
• Each site location was plotted onto
the land-cover maps and a buffer
zone of 1km was drawn around
each
• For each site, habitat data
(dissolved oxygen, temperature,
pH and conductivity,…)
Morris A.L. et al. (submitted). Land-use/deforestation-mediated food web
collapse promotes infectious disease carrying species in tropical freshwater
systems.
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Studying freshwater food webs and MU
determines the primary
production source
responsible for the energy
flow
indicates the trophic level
position of various aquatic
organisms
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Studying freshwater food webs and MU
The average δ15N and δ13C in bi-plot space for all recorded host and non-host organisms from the 17 sites
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Studying freshwater food webs and MU
determines the primary
production source
responsible for the energy
flow
indicates the trophic level
position of various aquatic
organisms
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Studying freshwater food webs and MU
The average δ15N and δ13C in bi-plot space for all recorded host and non-host organisms from the 17 sites
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Studying freshwater food webs and MU
MU trophic niche width and variability Total convex hull area of the mean δ13C and δ 15N isotopic readings in
bi-plot space
defines niche width
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Studying freshwater food webs and MU
Land cover data of the sites and its evolution in time Top chat shows the m2 cover of agricultural and urban land around
each site (3 buffer zones), and the bottom chart shows the m2
cover of deforestation within the 3 years prior to the surveys
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Studying freshwater food webs and MU
As deforestation increases, so niche width of organisms (hosts and non-hosts for MU) strongly decreases, and the effect of
agricultural and urban land cover appears to be less important
defines niche width
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Reconstructing food webs and MU
As deforestation increases, so niche width of organisms (hosts and non-hosts for MU) strongly decreases, and the effect of
agricultural and urban land cover appears to be less important
• Food web networks for each site using a combination of prior knowledge and the allometric diet breadth model
(ADBM)
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Reconstructing food webs and MU
As deforestation increases, so niche width of organisms (hosts and non-hosts for MU) strongly decreases, and the effect of
agricultural and urban land cover appears to be less important
• Food web networks for each site using a combination of prior knowledge and the allometric diet breadth model
(ADBM)
• Metrics calculated for each network
- Connectance: measure of the number of node connections
- Generality: a measure of the average number of differing organisms a taxa
is able to feed on
- Vulnerability: a measure of the average number of species an organism is
preyed upon by
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Reconstructing food webs and MU
Deforestation and land-use changes or agriculture lead to a decrease in the mean vulnerability of taxa, coupled with a decrease in
generality
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Summary of results on MU in French Guiana
• Decline in trophic niche width from deforestation and agricultural
urban intrusion has a powerful effect on aquatic food web networks
• This leads to a decrease in the mean vulnerability of (host
carrier) taxa (predator diversity), coupled with a decrease in
generality (prey diversity)
• It is likely that these decreases are both being driven by a loss in
the overall number of predators, allowing low-level trophic
organisms to flourish through a knock-on process
• Important effect on the potential for systems to harbour MU, as
taxa, which carry a high level of bacilli, are most abundant at sites
where there is a very low level of vulnerability and a mid-level of
generality
• Huge number of host carrier species
• BU outbreaks triggered by combinations of short- and long-
term rainfall patterns
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Global understanding of BU processes
Increased rainfall and variability
Flooding
Rainforest
Deforestation
and development
of agriculture
Functional changes in communities
Increased BU risk
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Rolland Ruffine (IRD) LabEx CEBA
Benjamin Roche (IRD) ANR EXTRA-MU
Elsa Canard (CNRS) BIOHOPSYS
Gabriel Garcia-Pena (IRD) IRD
Andrés Garchitorena (EHESP/IRD) CNRS
Aaron Morris (BU/IRD) Univ. Montpellier
Daniel Sanhueza (IRD, INSERM) INSERM
Kevin Carolan (IRD) Alliance ALLENVI
Rodolphe Gozlan (IRD) Alliance AVIESAN
Laurent Marsollier (INSERM) FRB/CESAB/BIODIS
Jérémie Babonneau (INSERM) WHO/Buruli ulcer
Pierre Couppié (CHC/Epat) FutureEarth/ecoHEALTH
Acknowledgements
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Important other results coming soon
Generalized linear models fitted on regional prevalence
of MU in 36 pairs of lotic communities in Cameroon. Based on AIC, the final models were selected by stepwise selection of variables
Gabriel Garcia-Pena
Postdoc fellow CESAB/FRB
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Important other results coming soon
Modelling MU transmission to human
Pathogen
Mycobacterium
ulcerans Water bugs
(Naucoridae or Belostomatidae)
Centre d’Etude de la Biodiversité Amazonienne - © 2012
Important other results coming soon
Modelling MU transmission to human
Pathogen
Mycobacterium
ulcerans Water bugs
(Naucoridae or Belostomatidae)
Andrés Benjamin Calistus
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