Transcript Slide 1

FOODBORN DISEASES
- Outbreaks investigation -
17/7/2015
N. Charisis, WHO/MZCC
1
TERMINOLOGY
Case
An individual who has
fallen ill following
ingestion of food
17/7/2015
N. Charisis, WHO/MZCC
2
Outbreak of foodborne disease
two or more people
present the same disease
where the laboratory tests indicate that
the food was the vehicle of the disease
17/7/2015
N. Charisis, WHO/MZCC
3
TERMINOLOGY
Epidemiological Surveillance in productive animals
Continuous and systematic collection, analysis, interpretation and
dissemination of data concerning the incidence of food borne pathogens in
livestock
Microbiological Surveillance in food
Continuous and systematic collection, analysis, interpretation and
dissemination of data concerning the distribution of food borne pathogens in
food
East
Epidemiological Surveillance in a population
Continuous and systematic collection, analysis, interpretation and dissemination
of data concerning the distribution of a disease in a population
17/7/2015
N. Charisis, WHO/MZCC
4
Is difficult to determine the true percentage
of enteric diseases
? Cases are
REPORED???
?Lab diagnose the
Illness
??Doctors orders a
diagnostic test
???Patients visit a doctor
or clinic
People ill in the population
17/7/2015
N. Charisis, WHO/MZCC
5
Identification of agent
…quick outbreak notification leads to a
quick investigation increases the possibilities of
isolation of the causal agent in stool, vomit specimens, even leftovers of food.
This can lead the investigator back to the restaurant, supermarket, factory or farm
where the raw material came from
Location of the establishment
Suspected FBD
Verification of the pathogen
RESTAURANT
Contaminated
FARM
Food incriminated
Origin of infection
17/7/2015
N. Charisis, WHO/MZCC
6
Is it always possible to find the food responsible for a FB
outbreak ?
NO
WHY?
Leftovers may not be available
Illnesses attributed to specific pathogen
may be acquired through non-foodborne routes
i.e. E. Coli through
animal feces or
workers or dirty
surfaces etc
Common bacterial strains may contaminate a number of
different foods
Sick persons may themselves contaminate foods that
they are handling
17/7/2015
N. Charisis, WHO/MZCC
7
Also…the incidence of FBI in a particular population is difficult to assess….
WHY?
Not all infected patients display symptoms of disease
From those who present symptoms,
- few report to a hospital
- fewer give cultures for examination
17/7/2015
N. Charisis, WHO/MZCC
8
Study performed by the
Food Safety Authority
(in London, year2000)
Lab – confirmed
& reported case
 A 19.4 % of the population surveyed reported that
they had experienced food poisoning in the past
year
Positive
Lab test
 24% of those people had not reported it
Lab test
 17% presented to a Doctor
Specimen taken
Person seeks care
Person becomes ill
 Only 64% of those who visited a doctor had
clinical specimens taken for laboratory
examination.
Population exposure
17/7/2015
N. Charisis, WHO/MZCC
9
LABORATORY TESTS in Foodborne
Diseases
a positive Lab test is usually acceptable
but…..
(false positive?)
a negative Lab test may be explained in different ways:
The patient may have symptoms but is not infected
The patient is infected with another pathogen (with similar symptoms)
The specific test is unable to reveal the specific pathogen (so is a
false negative test)
17/7/2015
N. Charisis, WHO/MZCC
10
Data Collection
in the
E.U.
Due to many differences of National Surveillance Systems
The results may not be comparable
For this reason:
1. New Directives for data collection
2. Nomination of E.U. Collection and Analyzing Institutions
3. Development of e-form collection of data
4. Establishing reference laboratories and recognized Lab techniques
17/7/2015
N. Charisis, WHO/MZCC
11
ARMONISATION OF E.U. Legislation
In order to harmonize legislation it is required to:
1.
Define the population at risk
2.
Use “case” definitions
3.
Use standard procedures (Lab techniques)
17/7/2015
N. Charisis, WHO/MZCC
12
HARMONISATION OF
PUBLIC HEALTH SURVEILLANCE IN THE EU
…
DECISION 2000/96/EC
List of communicable diseases to be placed under EU surveillance
DECISION 2000/57/EC
Establishment of an Early Warning & Response System (EWRS) for
the prevention & control of communicable diseases.
DECISION 2002/253/EC
Case definitions for communicable diseases
17/7/2015
N. Charisis, WHO/MZCC
13
DECISION 2000/96/EC:
List of communicable diseases to be placed under
EU surveillance:
Diseases preventable by vaccination
Sexually-transmitted diseases
Viral hepatitis (A- foodborne, E-waterborne)
Foodborne diseases
Waterborne diseases & diseases of environmental origin
Nosocomial infections
Other diseases transmissible by non-conventional agents
(including CJD)
Diseases covered by the international health regulations
(yellow fever, cholera, plague)
Other diseases (rabies, typhus, VHFs, malaria and any other
as yet unclassified serious epidemic disease etc.)
17/7/2015
N. Charisis, WHO/MZCC
14
DECISION 2000/57/EC:
Early Warning & Response System (EWRS) for the
prevention & control of Communicable Diseases
1. Events to be reported:
Outbreaks extending to more than one MS
Clustering (grouping) of similar cases when there is risk of
propagation between MS
Communicable Diseases, which requires EU action to be
constrained
2. Levels of system activation:
Information exchange
Potential threat
Definite threat
17/7/2015
N. Charisis, WHO/MZCC
15
DECISION
2002/253/EC:
DECISION
2000/57/EC:
List of F&WB CD for which a case definition is provided:
Botulism foodborne
Yersiniosis
Brucellosis
Campylobacter infection
Cholera
Cryptosporidiosis
Echinococcus
Toxoplasmosis
Trichinosis
EHEC
Giardiasis
Hepatitis A
Listeriosis
v-CJD
Salmonellosis
Shigellosis
Typhoid/paratyphoid
17/7/2015
N. Charisis, WHO/MZCC
16
DECISION 2002/253/EC:
Case definitions of FB & WB CD for
reporting to EFSA (European Food Safety Authority):
Confirmed case (verified by laboratory analysis)
Probable case (clear clinical picture or case linked
epidemiologically to a confirmed case)
Possible - but not Probable case
(indicative clinical picture but not confirmed or been probable)
Case with epidemiological link (contact
with the patient or exposure to same food, restaurant, Hotel,
house etc)
17/7/2015
N. Charisis, WHO/MZCC
17
FOOD SURVEILLANCE IN THE EU
RAPID ALERT SYSTEM (RASFF)
FOR FOOD & FEED
1. Legal status:
2. Purpose:
REG. EC/178/2002
To provide the control authorities with an
effective tool for exchanging info on
measures to be taken to ensure food safety
3. Levels of activation:
- Alert notification: Immediate action is required,
(i.e. Product withdrawal/recall)
- Information notification: No immediate action is required
(i.e. Product is not in market any more)
- News: Any other information on food & feed safety
17/7/2015
N. Charisis, WHO/MZCC
18
The Benefits of Surveillance
…
Identification of outbreaks
Recognition of emerging pathogens
Identification of sources
Identification of risk factors
Credible risk estimates
Improve risk management!
17/7/2015
N. Charisis, WHO/MZCC
19
Outbreak Investigation procedures
The Detection of an outbreak is followed by its investigation. But, who is responsible for
the investigation and what is the role of each profession?
Doctor
Microbiologist
Health worker
Doctors suspect foodborne disease - ask for laboratory diagnostic tests
Epidemiological research
Microbiologists isolate the causative agent - immediately report to the Health authorities
Health inspectors interview the persons at risk and collect more samples for the Laboratories;
Type of Investigation : What food did the patients eat? What food did the people who remained healthy
eat?
Formulation of hypotheses: Will – eventually – all people who eat contaminated food, be ill or not?
Epidemiologists are processing and analyzing the data, formulating epidemiological associations from
initial information;
Finally, Epidemiologists, Veterinarians and Physicians work together in order to formulate a ‘hypothesis’
and suggest the measures to be taken.
An outbreak investigation may be:
17/7/2015
- easy (if patients are known, i.e. school children, or prisoners), or,
N. Charisis,
WHO/MZCC
- very
difficult (foodborne
diseases at home ord diseases due to street vendors)20
Why the need for an outbreak investigation?
TO CONTROL THE OUTBREAK !
In
order
to
control
the
OUTBREAK what we should do ?
What we should do to prevent
similar outbreaks?
Withdrawal of the suspected food or water
Publication of results (very useful for health
policy-makers,
producers,
distributors,
handlers and consumers,
WHY ?
To prevent further cases of foodborne disease
To be a source of information on routes of transmission of specific pathogens and
To identify high-risk environments and high-risk handling or processing practices
17/7/2015
N. Charisis, WHO/MZCC
21
How simple is an epidemiological investigation?
1000
2000 students
1000
University Kitchen
FOOD
Case
Total
(People with Symptoms )
Controls
(Remained well)
Steak
80
920
1.000
Fish
5
995
1.000
Total
85
1.915
2.000
The possibility of being poisoned because of the steak is:
80 X 995
5 X 920
17/7/2015
=
17.3 a high probability
The fish probability =0,058
N. Charisis, WHO/MZCC
22
HOWEVER
- Individual resistance
A. Not all who ate steak fall ill !
- Acid pH
- Use of Coca-cola
Why?
- Use of wine
- Other reasons
B. Some who didn’t eat steak fall ill !
- unknown reasons
Why?
T H E R F O R E
17/7/2015
N. Charisis, WHO/MZCC
23
The PROOF should depend on:
1. Isolation of microorganisms from food leftovers
2. Isolation from stools
3. Isolation from vomit
4. Isolation from food handlers (hands, nose, stools)
5. Isolation from kitchen surfaces (presece of insects,
17/7/2015
N. Charisis, WHO/MZCC
rodents)
24
Control measures taken in an outbreak
Recalling a food product or closing a food premise can have serious economic and
legal sequences.
Implementing control measures is often a balancing act
between the responsibility to prevent further cases and the
need to
Reputation
protect the credibility of a company.
17/7/2015
Health
N. Charisis, WHO/MZCC
25
Once the investigations have identified that a food or a food premise is associated with
transmission of the suspected pathogen, measures should be taken to control the
source.
The steps may include:
Removing implicated foods from the market (food recall, food seizure),
Modifying a food production or preparation process and
Closing food premises or prohibiting the sale or use of suspect foods.
17/7/2015
N. Charisis, WHO/MZCC
26
A food recall
the business recalls the product from the market. It may be initiated by the business itself
or on request of an appropriate health authority.
A food seizure the appropriate authority removes a food product from the market
if the business does not comply with recall.
Before recalling the public should be informed for the:
NAME OF THE
PRODUCT
ADDRESS OF
PRODUCTION SITE
17/7/2015
REASON FOR
RECALL
N. Charisis, WHO/MZCC
LOCATION WHERE
THE PRODUCT
MAY BE SOLD
27