guégan jf 20150708_1730_upmc_jussieu_-_room_105 (conflit lié au codage unicode)

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: [email protected]

[email protected]

U.N. Climate Change Conference COP-21, Paris, July 2015


Buruli ulcer and French Guiana

in a Nutshell


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)


Work done within the meta-

programme BIOHOPSYS

from LabEx CEBA


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


Population dynamics of

Buruli ulcer cases in

French Guiana


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



occurring on short (i.e., seasonal) temporal scale

2nd temporal scale suggests cases peak during periods of high

levels in rainfall variation


BU outbreaks can be triggered by combinations,

i.e. annual and long-term, of rainfall patterns


Mycobacterium ulcerans

persistence and dynamics in

aquatic systems


• 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


% in

fect

ed s

amp

les

MU is near everywhere, it depends if you look at or not!

Everywhere Somewhere


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)



French Guiana

10 functional groups



French Guiana

M. ulcerans


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.



determines the primary

production source

responsible for the energy

flow

indicates the trophic level

position of various aquatic

organisms



The average δ15N and δ13C in bi-plot space for all recorded host and non-host organisms from the 17 sites



determines the primary

production source

responsible for the energy

flow

indicates the trophic level

position of various aquatic

organisms



The average δ15N and δ13C in bi-plot space for all recorded host and non-host organisms from the 17 sites



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



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



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


Reconstructing food webs and MU



• Food web networks for each site using a combination of prior knowledge and the allometric diet breadth model

(ADBM)





• 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



Deforestation and land-use changes or agriculture lead to a decrease in the mean vulnerability of taxa, coupled with a decrease in

generality


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


Global understanding of BU processes

Increased rainfall and variability

Flooding

Rainforest

Deforestation

and development

of agriculture

Functional changes in communities

Increased BU risk


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


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



Modelling MU transmission to human

Pathogen

Mycobacterium

ulcerans Water bugs

(Naucoridae or Belostomatidae)



Modelling MU transmission to human

Pathogen

Mycobacterium

ulcerans Water bugs

(Naucoridae or Belostomatidae)

Andrés Benjamin Calistus



The probability of vector-borne transmission

by water bugs is highly not probable when

compared to environmental transmission

guégan jf 20150708_1730_upmc_jussieu_-_room_105 (conflit lié au codage unicode)

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