spreading of diseases along river networks

Rivers, rainfall and cholera.

A new challenge for hydrologists

Enrico Bertuzzo, Senior Scientist, ECHO lab, EPFL

Interdisciplinary Workshop

on Frontiers in Hydrology and Hydrogeoscience

humanbacteria in the

environment

ingestion of

contaminated water

fecal contamination

ecological dynamics

• Mortality rate less than 1% if properly treated

• Recovery time of about 5 days

• Immunity is acquired after infection; not permanent, lasts a few years (1–5?)

the model

Continuous Compartmental

Spatially Explicit Epidemic Model

S susceptible

I infected

R recovered

B bacteria concentration in the

environment

S susceptible

I infected

R recovered

B bacteria concentration in the

environment

Pij hydrologic transport network

Continuous Compartmental

Spatially Explicit Epidemic Model

Continuous Compartmental

Spatially Explicit Epidemic Model

S susceptible

I infected

R recovered

B bacteria concentration in the

environment

Pij hydrologic transport network

Qij human mobility transport

network

Continuous Compartmental

Spatially Explicit Epidemic Model

S susceptible

I infected

R recovered

B bacteria concentration in the

environment

Pij hydrologic transport network

Qij human mobility transport

network

Haiti cholera epidemic

Haiti cholera epidemic. First case on October 2010

As of April 15 2014:

00’000 reported cases (7% of the population)

’552 deaths (1.2% of the total cases)

Digital Terrain Model

SRTM3

network and watershed

delineation

definition of the graph

hydrologic transport

Digital Terrain Model

SRTM3

network and watershed

delineation

LandScan Project

1 km resolution population

distribution: downscaling of

census data through remote

sensing

Road Network

source: openstreetmap.org

distances between

communities

human-mediated

transport network

Road Network

source: openstreetmap.org

distances between

communities

Rinaldo et al. PNAS 2012

prediction Dec 2010Bertuzzo et al., GRL, 2011

prediction Nov 2011Rinaldo et al., PNAS, 2012

prediction Jan 2013Bertuzzo et al., in press SERRA

Stability analysis

unstable disease

free equilibrium

perturbation (I>0)

epidemic outbreak

10R

stable disease

free equilibrium

perturbation (I>0)

epidemic fades out

Basic reproduction number: number of secondary cases produced by a single

case over the course of the infectious period

10R

Stability conditionsspatially implicit model

spatially explicit model

Stability conditions

eigenvectorcases

leading eigenvalue

Intervention strategies

Intervention strategies

300’000 vaccines

3’000’000 vaccines

sanitation 40%

sanitation 40%

Epidemic or endemic?

probability of extinction

thanks for the attention