Lassa Fever Case Study

Njala University

Thomas Winnebah

Bashiru Koroma

Morrison Lahai

Alie Kamara

Alhaji Gogra

John Borway

Institute of Development Studies

Melissa Leach

Annie Wilkinson

Catherine Grant

Tulane University

Lina Moses

Kenema Government Hospital

Donald Grant

James Koninga

Lansana Kanneh

Franklyn Kanneh

Momoh Foday

Special thanks to the communities of

Lalehun Kovoma

Lambayama (Kenema)

Largo Square (Segbwema)

Majihun

Lassa Fever

• Viral hemorrhagic fever endemic to West Africa

• Mortality up to 69% Kenema Government Hospital, Sierra Leone (Shaffer et al. 2014 PLoS NTD)

• Rodent reservoir: Mastomys natalensis

• Where and how are people getting

infected?• West African subspecies

(Redding et al. 2016 Mol Ecol Evol)

• Rodent to human transmission: 80%

(Lo Iocono et al. 2015 PLoS NTD)

Photo: Dan Bausch

Photo: Lina Moses

Image: David Redding

Lassa Fever Case Study

• Land use impact on small mammal abundance, M. natalensis

• Livelihood practices and ecosystems service uses that increase/decrease exposure to M. natalensis

• Virus regulation as an ecosystems service (human and rodent infection)

• Local knowledge of disease transmission and prevention

Lambayama Section, Kenema

Majihun Lalehun Kovoma

Largo Square Section, Segbwema

Spatial Dimensions

Lalehun Kovoma

OC

T

NO

V

DEC

JAN

FEB

MA

R

AP

R

MA

Y

JUN

JUL

AU

G

SEP

OC

T

NO

V

DEC

JAN

Har

vest

Bu

rnin

g

Bru

shin

g

Pla

nti

ng

Upland Cycle

2 years of data collection

2013 2014 2015

FEB

MA

R

AP

R

MA

Y

JUN

JUL

AU

G

Four points of data collection

Tran

sect

map

pin

gFo

cus

gro

up

sTr

app

ing

Blo

od

sam

plin

g

Focu

s gr

ou

ps

Trap

pin

gB

loo

d s

amp

ling

Focu

s gr

ou

ps

Trap

pin

gB

loo

d s

amp

ling

Trap

pin

g

Swamp Cycle

Wee

din

g,

bir

d m

gmt

Wee

din

g,

bir

d m

gmt

Har

vest

Har

vest

Har

vest

Veg

etab

le

gard

enin

g

Soil

pre

p,

pla

nti

ng

Veg

etab

le

gard

enin

g

Soil

pre

p,

pla

nti

ng

Bu

rnin

g

Bru

shin

g

Pla

nti

ng

EBOLA

Temporal Dimensions

0.0%

0.5%

1.0%

1.5%

2.0%

2.5%

3.0%

3.5%

OctNov 13 FebMar 14 MayJ 14 AugS 15

Cleared

Old fallow

Swamp rice

Upland mixed

Young fallow

Total

Mastomys Trap Success by Land Use and Season

Fallow land recently cleared for upland mixed crops

Swamp vegetable, post rice harvest

Upland soil prep, planting

Oct 2013 Mar 2014 May 2014 Aug 2015

Fallow land recently cleared—Feb/March

Men: convert bush to farm—brushing, felling trees, burning; use of tools, fireWomen and children: feed work parties, bring food and water, gather and bundle fuel wood

Swamp Vegetable Garden, post rice harvest—Feb/March

Women: Vegetable gardening using hands intensively. Independent income source.

Upland Soil Preparation and Planting—May

Women, men and children all involved in planting rice, ground nuts, intercrops. Land (and burrows?) significantly disturbed

Seasonal Peaks of Lassa Fever cases reporting to Kenema Government Hospital 2008-2012

Peak of M. natalensisabundance in cleared and swamp land

Peak of M. natalensisabundance in upland farms

(Shaffer et al. 2014, PLoS NTD)

This study also showed Lassa fever for women

Analyses in Progress

• Human Lassa Antibody Seroconversions• Gender and age distribution• Association with agricultural activities

• Integrating data on local understanding of rodent, diseases, and their control

• Virus incidence in small mammal populations• Species richness, disease regulation• Interspecific competition

Key findings• Peak abundance of Mastomys coincides with

times of significant human-driven land

perturbation

• This perturbation is gender and age specific.

• This coincides with peak seasons in Lassa fever incidence• Seroconversion data will give better insight

• Lassa fever disease system should be examined in the context of ecosystems services• Mastomys as protein source

• Mastomys as agricultural pest and disease reservoir

• Potential cross-cutting with agricultural sector

This work, Dynamic Drivers of Disease in Africa Consortium, NERC project numberNE-J001570-1, was funded with support from the Ecosystem Services for Poverty Alleviation (ESPA)programme. The ESPA programme is funded by the Department for International Development (DFID), theEconomic and Social Research Council (ESRC) and the Natural Environment Research Council (NERC).