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Food-borne outbreakinvestigation
10 June 2014Carmen Varela Martinez
Directive 2003/99/EC:• An incidence, observed under given
circumstances, of two or more human cases of the same disease and/or infection, or a situation in which the observed number of human cases exceeds the expected number and where the cases are linked, or are probably linked, to the same food source.
Food-borne outbreak definition
Aim of food-borne outbreak investigation
Identification of:– Causative agent
– Implicated food
– Contributory factors
In order to:– Control the outbreak
– Prevent similar outbreaks
Steps in food-borne outbreak investigation
Detection
Finding cases
Generating hypotheses
Testing hypotheses and finding the source
Control the outbreak
Epidemiological Surveillance in Spain
Notifiable DiseasesOutbreaks System
Source:Physicians
Microbiology Information SystemSource:
Microbiology Labs
Local
Autonomous Regions
NationalCentre of Epidemiology
International
Detection
Food-borne outbreaks. Spain 1976-2012
*
Source: National Network of Epidemiological SurveillanceElaboration: National Centre of Epidemiology * Provisional data
Detection
Detection
No of Cases
654321
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
2010
Sampling date
Salmonella Poona cases. Spain 2010
Source: National Network of Epidemiological SurveillanceElaboration: National Centre of Epidemiology
Detection
Detection
Listeria cases. Spain 2012
Index cases
Each colour shows one autonomous regionSource: National Network of Epidemiological SurveillanceElaboration: National Centre of Epidemiology
Detection
Salmonella food-borne outbreaks. Spain 2002-2012*.
Source: National Network of Epidemiological SurveillanceElaboration: National Centre of Epidemiology * Provisional data
0
10
20
30
40
50
60
70
Serotyped Serotypes diferent thanEnteritidis andTyphimurium
Phagotyped
% of Salmon
ella outbreaks
Typing
N=425157.4
1.2 1.9
Finding casesCase definition:
Sensitivity versus specificity
Generating hypotheses
Questionnaire for description of the outbreak:
– Disease / Causative agent
– Place: Setting
– Time: Epidemic curve
– Person: age, sex, ocupation, etc.
– Common exposure: food, travel, animal, etc.
Generating hypothesesb.1) Food intake (72 hours before onset of symptoms): Food Branch Batch Place of
acquisition Date of
acquisition Eggs and egg products
Cakes/Ice creams
Milk/ yoghourt
Cheese
Chicken
Pig
Meat products “Embutido”:
salchichón
chorizo
lomo
jamón serrano
jamón york
chistorra
otros:
__________________
__________________
__________________
Sausages
Minced meat
Other meat
Tap water
Bottle water
Generating hypotheses
b.2) Food preferences (food intake per week): Food Never 1 per week 2 per week 3 per week >3 per weekEggs and egg
products
Cakes/Ice
creams
Milk/ yoghourt
Cheese
Chicken
Pig
“Embutido”
Sausages
Minced meat
Other meat
Generating hypotheses
No of Cases Cases < 1 yearCases >= 1 year
654321
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
2010
Sampling dateSource: National Network of Epidemiological SurveillanceElaboration: National Centre of Epidemiology
Testing hypotheses, finding the source
EFSA
Epidemiological evidence (whether descriptive or analytical)
– Strong or week
Microbiological evidence– Strong or week
EU summary report on zoonoses, zoonotic agents and food-borne outbreaks 2012. EFSA
Testing hypotheses, finding the source
Testing hypotheses, finding the source
EU summary report on zoonoses, zoonotic agents and food-borne outbreaks 2012. EFSA
EU summary report on zoonoses, zoonotic agents and food-borne outbreaks 2012. EFSA
Testing hypotheses, finding the source
Food-borne outbreaks with unknown causative agent. Spain 2002-2012*.
0
5
10
15
20
25
30
35
40
45
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
% of o
utbreaks
Year
Source: National Network of Epidemiological SurveillanceElaboration: National Centre of Epidemiology * Provisional data
N=8739
Causative agent unknown
2002‐2009 33,382010‐2012 28,17
Χ2=16,99p=0,000038
Testing hypotheses, finding the source
0
5
10
15
20
25
30
35
40
45
50
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
% of o
utbreaks
Year
Microbiological
Epidemiological
Both
Food-borne outbreaks according to the type of evidence. Spain 2002-2012*.
Source: National Network of Epidemiological SurveillanceElaboration: National Centre of Epidemiology * Provisional data
N=8739
Testing hypotheses, finding the source
0
10
20
30
40
50
60
70
80
90
100
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
% of o
utbreaks
Year
Food-borne outbreaks with at least one sample analysed. Spain 2002-2012*.
Source: National Network of Epidemiological SurveillanceElaboration: National Centre of Epidemiology * Provisional data
N=8739
Testing hypotheses, finding the source
0
5
10
15
20
25
30
35
40
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
% of o
utbreaks
Year
Food-borne outbreaks mentioning a food item. Spain 2002-2012*.
Source: National Network of Epidemiological SurveillanceElaboration: National Centre of Epidemiology * Provisional data
N=8604
Testing hypotheses, finding the source
Testing hypotheses, finding the source
Cheese3%
Eggs/egg products45%
Chicken4%
Fish6%
Sellfish8%
Cakes5%
Mix7%
Others22%
Source: National Network of Epidemiological SurveillanceElaboration: National Centre of Epidemiology * Provisional data
Food-borne outbreaks according to the reported food. Spain 2002-2012*.
N=8604
Contaminated ingredient
15%
Storage time/temperature
abuse17%
Inadequate heat treatment
4%
Inadequate chilling11%
Cross‐contamination18%
Infected food handler3%
Other 1%
Unknown31%
Contributory factors reported in food-borne outbreaks. Spain 2002-2012*.
Source: National Network of Epidemiological SurveillanceElaboration: National Centre of Epidemiology * Provisional data
N=11550
Testing hypotheses, finding the source
No of outbreaks according transmission mode. Spain 2012*
1%
57%
42%
Food Water Other
Source: National Network of Epidemiological SurveillanceElaboration: National Centre of Epidemiology * Provisional data
N=1259
Testing hypotheses, finding the source
Imported food-borne outbreaks according to country of infection. Spain 2002-2012*.
Source: National Network of Epidemiological SurveillanceElaboration: National Centre of Epidemiology * Provisional data
Not specified Bulgaria Colombia Cuba Denmark Ecuador Egypt India Italy Morocco Namibia PortugalEscherichia coli 1L.monocytogenes 1Salmonella 1 4S.Typhi/S.Paratyphi 1Shigella 2 2V.cholerae 1Trichinella 1 1Virus hepatitis A 1 1 1 6 1Norovirus 1 1Unknown 1 2 7
TOTAL 2 1 1 1 1 1 1 4 1 10 1 13
Testing hypotheses, finding the source
Control the outbreak
0 500 1000 1500 2000 2500 3000 3500 4000 4500
Facilities inspection
Hygiene education
Unknown
Food handler control
Contact tracing
Specified treatment
Food detention
Cessation of activity
Disciplinary procedure
Deficiency repairing
Desinfection
Other
Isolation
Immunization
Mea
sure
s
No of measuresSource: National Network of Epidemiological SurveillanceElaboration: National Centre of Epidemiology * Provisional data
implemented measures in food-borne outbreaks. Spain 2002-2012*.
N=12848
Conclusions
Typing information added to the epidemiological
data is of great value in the investigation of
food-borne outbreaks.– ECDC is supporting molecular typing initiatives.
Web based tools together with social networks
can facilitate the investigation of food-borne
outbreaks.
Conclusions
Investigation of food-borne outbreaks differs
among EU Member States.
To achieve a higher proportion of food-borne
outbreaks with strong epidemiological and/or
microbiological evidence would lead to a better
prevention and control of them.