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Lessons learned from the West African Ebola outbreak, Marion Koopmans, ERS [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
F Keesing et al. Nature 468, 647-652 (2010) doi:10.1038/nature09575
Drivers and locations of emergence events for zoonotic infectious diseases in humans from 1940–2005.
Probability of further spread greatly increased
Population growth Global travel and trade
1950
2000
2015
Probability of stage 2 and 3 infection depends on:
1.Host abundance2.Fraction infected3.Frequency of 'encounters’ 4.Probability of transmission
per encounter
• phylo distance host • microbe's characteristics• Host characteristics
Wolfe et al., 2007
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
< 2 yr old
< seeding through HCW
Diagnose
Feldmann and Geisbert, 2011
Family Filoviridaegenus Marburg virusesGenus 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
Soluble GP, frequency depends on sequence specific RNA editing (Mohan et al., 2012)
2.2 × 10-4 - 7.06 × 10-4 nucleotide substitutions/site/year (Caroll et al., 2013)
Animal surveillance for Ebola, Gabon 2001-3
Rouquet et al., 2005
Outbreaks in animals detected prior to (4/5) human disease outbreaks
Convincing evidence for bushmeat related introductions
Fruit batsDuikersPrimates
Saez et al., EMBO Mol Med, 2014
Single zoonotic event in Meliandou, bat-borne, followed by human2human transmisison
Fruit Bats as reservoir for EBOV
Leroy et al., 2005
Overlapping ecological nicheNo symptomsInfection cyclicalPotential source of introduction into West Africa
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
Towner et al., 2004; Ksiazeck et al., 1999; Reusken et al., 2014
1. Fatal cases higher loads than survivors2. Early cases can test negative (depending on detection limit of
assay)3. Late samples can test negative, but whether these persons could
transmit is unknown4. Fatal cases rarely mount antibody response5. Are the data the same for the current strain?
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 contactBody fluids of severely ill and deceased patientsNo airborne Tx
>
Contact precautionsQuarantineSafe burials
WHO, NEJM, 2014; Kilmarx et al., 2014Mackay, based on WHO reports http://virologydownunder.blogspot.com.au/
Exponential growth phaseRo estimates:
Liberia 1.5Sierra Leone 1.4Guinee 1.8
Shifting factors contributing to HCAI:
Awareness>availability of PPE>contact in social environment>fatigue
9% of total health workforce!
Incidence of Ebola, HCW
Sierra Leone, May-October
3,854 casesOf 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: 0.46outside Africa: 0.17Sierra Leone: 0.05
Chevallier et al., 2014
http://www.npr.org/sections/health-shots/2014/10/02/352983774/no-seriously-how-contagious-is-ebola
How infectious 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/hdr14-report-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