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Lessons learned from the West African Ebola outbreak,
Marion Koopmans, ERS 2015
[email protected] ; @MarionKoopmans
Wilson, M.L., Ecology and infectious disease, in Ecosystem Change and Public Health: A Global
Perspective, J.L. Aron and J.A. Patz, Editors. 2001, Johns Hopkins University Press: Baltimore. p. 283-324.
http://www.gao.gov/products/GAO-12-55
Drivers and locations of emergence events for zoonotic
infectious diseases in humans from 1940–2005.
F Keesing et al. Nature 468, 647-652 (2010) doi:10.1038/nature09575
Probability of further spread greatly increased
Population growth
2015
2000
1950
Global travel and trade
Probability of stage 2 and 3
infection depends on:
1.Host abundance
2.Fraction infected
3.Frequency of 'encounters’
4.Probability of transmission
per encounter
•
•
•
Wolfe et al., 2007
phylo distance host
microbe's characteristics
Host characteristics
Start outbreak EBOV
 March 10, 2014 notification unknown disease characterized by fever, severe
diarrhea, vomiting and high fatality rate in Guéckédou and Macenta in Guinea.
 March 22, EVD reported by Guinea to WHO.
 March 27, EVD suspected cases in Liberia and Sierra Leone related to
outbreak in Guinea.
 April 3d: ZEBOV Dx
Time to diagnosis:
> 3 weeks
*
Gastro-enteritis syndrome at
clinical presentation
High case fatality rate
First outbreak in West Africa
Baize et al. 2014
Diagnose
< 2 yr old
< seeding
through HCW
Family Filoviridae
genus Marburg viruses
Genus Ebolaviruses.
Genus Cueva viruses
(Spain, New)
5 species:

Sudan (SUDV)

Zaire (EBOV)

Tai Forest (TAFV)

Bundibugyo (BDBV)

Reston (RESTV)
Case fatality rate 0-70%
Zaire EBOV highest
Feldmann and Geisbert, 2011
2.2 × 10-4 - 7.06 × 10-4 nucleotide
substitutions/site/year (Caroll et al., 2013)
Soluble GP, frequency depends on sequence
specific RNA editing (Mohan et al., 2012)
Animal surveillance for Ebola, Gabon 2001-3
Fruit bats
Duikers
Primates
Outbreaks in animals detected prior to (4/5) human disease outbreaks
Convincing evidence for bushmeat related introductions
Rouquet et al., 2005
Single zoonotic event in Meliandou, bat-borne,
followed by human2human transmisison
Saez et al., EMBO Mol Med, 2014
Fruit Bats as reservoir for EBOV
Overlapping ecological niche
No symptoms
Infection cyclical
Potential source of introduction into West Africa
Leroy et al., 2005
Potential under-reporting of Ebola (Schoepp et al., 2014)
Initial factors contributing to Ebola outbreak
 Bush meat consumption
 Outbreak in new region
 Non-specific syndrome
 Poor healthcare sector, delayed diagnostics
 Lack of PPE and training
 Cultural beliefs
> seemingly uncontrollable spread
Shedding kinetics Ebola
1. Fatal cases higher loads than survivors
2. Early cases can test negative (depending on detection limit of
assay)
3. Late samples can test negative, but whether these persons could
transmit is unknown
4. Fatal cases rarely mount antibody response
5. Are the data the same for the current strain?
Towner et al., 2004; Ksiazeck et al., 1999; Reusken et al., 2014
Courtesy of Pierre Rolin, US CDC
Nosocomial Tx Ebola
Ftika et al., Ebola Sudan, 2013
 AR Unprotected contact HCW 81%
 Limited physical contact HCW 21%
 Visiting same room 0%
Baron et al., Ebola Sudan 1983
 Unprotected HCW, nursing 67%
 Unprotected HCW, contact, no nursing 13%
Francesconi et al., Uganda, 2013
 Contact body fluids p<0.0001
 Funeral ritual p< 0.02
 Sharing meal, room , no increased risk
Borchert et al., Marburg outbreak, 2007
 Non-invasive procedures: 19% consistent use of PPE
 Invasive procedures: 29% consistent use of PPE
Direct contact
Body fluids of severely
ill and deceased
patients
No airborne Tx
>
Contact precautions
Quarantine
Safe burials
Exponential growth phase
Ro estimates:
9% of total health workforce!
Liberia 1.5
Sierra Leone 1.4
Guinee 1.8
Shifting factors contributing to HCAI:
Awareness>availability of PPE>contact in social environment>fatigue
WHO, NEJM, 2014; Kilmarx et al., 2014
Mackay, based on WHO reports http://virologydownunder.blogspot.com.au/
Incidence of Ebola, HCW
Sierra Leone, May-October
3,854 cases
Of these, 199 HCW
Population: 80.4 per 100,000
(1 in 1250)
HCW: 8,285 per 100,000
(1 in 12)
Kilmarx et al., 2014
Nosocomial transmission outside region
Toth et al., 2015
transmissions/case: 0.46
outside Africa: 0.17
Sierra Leone: 0.05
Chevallier et al., 2014
How infectious is ebola?
http://www.npr.org/sections/health-shots/2014/10/02/352983774/no-seriously-howcontagious-is-ebola
Control strategy
 Rapid case finding and ascertainment
 Local outbreak teams, laboratory capacity
 Isolation
 Holding centres, triage units, lab capacity
 Contact tracing
 Outbreak teams
 Decontamination
 Treatment
 Massive fluid replacement, electrolytes, malaria
 Social mobilization
 Certificates, education, patient care, post ebola care
 Surveillance
 Swab teams
Nrs 175, 179, and 183 on the UN human
development index (ranked from 1-185)
UN Human development index 2013http://issuu.com/undp/docs/hdr14report-en?e=3183072/9245907#search
Location of treatment centres
Big challenge: treatment and vaccine trials
Conclusions
 The Ebola outbreak is a clear example of the changing epidemiology of
emerging infections
 Ebola greatly overwhelmed local health infrastructures
 Long term stable and prepared infrastructures needed to address EID
threats
 Forward thinking in terms of vaccine and drug development needed for
low probability high impact diseases