Case 5 Flashcards
(51 cards)
1
Q
Foodborne disease
A
caused by consuming food contaminated by bacteria and/or their toxins, parasites, viruses, chemicals, or other agents (US FDA).
- Infections are the microorganism infecting and intoxication is the microorganism leading to toxins. Food poisoning would be the contamination of food with chemical toxins or microorganisms. Bacteria, Fungi, Virus, protozoa are all examples of microorganisms.
2
Q
Infection
A
Viable microorganism are ingested → multiply in human body
3
Q
Intoxication
A
Microbial/naturally occurring toxins are consumed in contaminated foods
4
Q
Bacteria
A
- Gram+ or Gram-
- Different shapes
- Mechanisms of action: Infection & intoxication
- Names: E.coli
Salmonella
Campylobacter
Clostridia
5
Q
Virus
A
- Generally enteric, transmitted by the faecal-oral route.
- Transmission by person-to-person contact and via contaminated water is common
- Mechanisms of action: Infection
- Names: Hepatitis A
Norovirus
6
Q
Prions
A
- Prions are misfolded proteins with the ability to transmit their misfolded shape onto normal variants of the same protein.
- Prion diseases can affect both humans and animals and are sometimes spread to humans by infected meat products.
- Mechanisms of action: Infection
- Names: Bovine
spongiform
encephalitis (BSE)
7
Q
Fungi
A
- Secondary metabolites of moulds that can induce acute and chronic symptoms: Carcinogenic, mutagenic, and estrogenic effects in humans and animals
- Principle fungi: Aspergillus, Penicillium, Fusarium
- Mechanisms of action: Intoxication
- Names: Mycotoxins
Aflatoxins
Ochratoxins
8
Q
Protozoa
A
- Unicellular organisms that colonise the intestinal epithelium and form cysts
- May survive for long periods in the environment
- Mechanisms of action: Infection
- Names: Giardia intestinalis
Entamoeba
Toxoplasma gondii
Cyclospora cayetanensis
Cryptosporidium parvum
9
Q
Parasites
A
- Organisms that live off other living organisms (hosts)
- Transmitted from animals to humans, from humans to humans, or from humans to animals
- Infective stages of parasites are eaten in raw or partially cooked protein foods, or in raw veggies and fruits inadequately washed → Live and reproduce within tissues and organs of infected human and animal hosts, often excreted in feces
- Complex life cycles involving 1-2 intermediate hosts
- Classified as:
• Helminths (multicellular worms): Trematodes, nematodes, cestodes
• Protozoa (Single-celled microscopic organisms): Cryptosposridia and Cyclospora
10
Q
Helminthes
A
- Helminthiasis, also known as worm infection, is any macroparasitic disease of humans and other animals in which a part of the body is infected with parasitic worms, known as helminths
- Names: Trichinella
11
Q
Hepatitis A virus
A
- One of the more severe foodborne disease
- immune destruction of liver cells
- virus can be shed in feces for up to 14 days before onset of illness -> possible for infected food handle with poor personal hygiene to contaminate food (virus may be shed in feces for 1-2 weeks after onset of symptoms)
- foods contaminated by infected persons or fecally contaminated water
- most heat enteric than most of enteric viruses + resistant to drying
12
Q
Norovirus
A
- First enteric virus reported to be foodborne
- Difficult to detect, especially from foods
- Transmission :
• Contact with infected individuals or fecally contaminated water/materials
• Shellfish: Frequently contaminated with human feces from sewage discharges
• Aerosolization of vomitus-containing virus particles
13
Q
Astrovirus
A
- Small, round viruses that have surface projections resembling a five or six-pointed star
- Incubation longer than norovirus (3-4 days), duration of illness is longer (7-14 days), vomiting is less common
- Predominant symptom: Diarrhea
14
Q
Rotavirus
A
- Single most important cause of infantile gastroenteritis worldwide
- Rotavirus genome consists of 11 segments of double-stranded RNA surrounded by a double-shelled viral capsid
- Incubation: 1-3 days
- Illness characterised by fever, vomiting, and diarrhea
- Long-term effect: hepatitis A, distraction of liver cells
15
Q
Trematode
A
- Involve 2 intermediate hosts
- Infection takes place through consumption of raw, undercooked, underprocessed freshwater fish or crustaceans containing infective stages of these parasites
- Diseases caused by foodborne trematodes: Cholangiocarcinoma, gallstones, severe liver disease, gastrointestinal problems
16
Q
Nematode
A
- Usual foods involved: Undercooked or raw fishery products
- Most common species: Anisakis simplex
- Commonly present in fish caught in the wild, most frequently in the liver and belly cavity, can also occur in the flesh
- Trichinella spiralis:
• Cause of trichinosis in humans
• Results from consumption of contaminated raw or undercooked pork or pork products
17
Q
Salmonella
A
Source: meat, eggs, poultry, raw milk, water, sprouts
Symptoms: nausea, abdominal cramps, diarrhea, fever, headache
Second most often reported zoonotic disease in humans
Statistically significant decreasing trend in notification rate in the EU
18
Q
Campylobacteriosis
A
Source: raw poultry, meat, unpasteurized milk, untreated water, chicken
Symptoms: abdominal cramps, blood stool, gastroenteritis, vomiting; long-term: growth-development disturbances, neurological disorders, kidney failure
Most common reported gastrointestinal bacterial pathogen in humans
Number of notified cases decreased with 5.0% compared to 2007
Campylobacter commonly detected from live poultry, pigs and cattle
19
Q
BSE (Bovine spongiform encephalopathy)
A
Source: infected cow meat (special parts of the cow)
Symptoms: brain-wasting, fatal within 6 months, involuntary movements, immobility, death
20
Q
Listeriosis
A
Source: fish, cheese, meat, sandwiches, ready-to-eat-food Symptoms: flu-like, sepsis, meningitis, death
Cases decreased by 11.1% since 2007
High fatality rate20.5%
21
Q
Escherichia coli
A
Source: raw or undercooked milk and meat, unpasteurized milk, seafood, cereal grains, contaminated water
Symptoms: stomach cramps, bloody diarrhea, kidney failure, dehydration, stroke, neurological symptoms, death in failure
Common bacteria in gastrointestinal tract
- here are e.coli in the human intestine that are beneficial(0.1mmol), but there are also pathogenic e.coli that release toxins.
- Toxicity depends on the amount of bacteria, immune response etc.
22
Q
Brucella
A
Brucellosis is a bacterial infection that spreads from animals to people. Most commonly, people are infected by eating raw or unpasteurized dairy products. Sometimes, the bacteria that cause brucellosis can spread through the air or through direct contact with infected animals
23
Q
Rabies
A
- Rabies is a viral disease that causes inflammation of the brain in humans and other mammals
- Early symptoms can include fever and tingling at the site of exposure
- it is spread when an infected animal bites or scratches a human or other animal.
24
Q
Yersinia
A
Yersiniosis is an infection caused most often by eating raw or undercooked pork contaminated with Yersinia enterocolitica bacteria. CDC estimates Y. enterocolitica causes almost 117,000 illnesses, 640 hospitalizations, and 35 deaths in the United States every year. Children are infected more often than adults, and the infection is more common in the winter.
25
Primary production
* Food of animal origin are most prone to infection by a wide range of pathogens
* Common action: segregating the farm animals from those living in the wild and from the environment (contrary to society’s desire for more ‘animal-friendly’ production
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Processing
* Presents opportunities to extensively reduce the levels of pathogens/ effective barrier
* E.g. pasteurization of milk
* Most decontamination methods do not result in the complete eradication of pathogens
* Preservation methods, packing materials, etc. impact on the occurrence of post-contamination
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Distribution
• Observance of general hygiene guidelines, including the use of effective refrigeration, is extremely important
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Consumer
* Can prevent many problems by ensuring that food is stored and prepared properly
* The person preparing the food can also be the source of pathogens to contaminate the food
29
5 steps by WHO (individual level)
Good hygiene
Separate cooking for different foods and use different/was knifes (raw or cooked; meat and vegetables)
Cook thoroughly
Keep food at safe temperature
Use safe water and raw materials; Wash fruits and vegetables before eating, eat fresh food (look at expiration date)
30
HACCP principles (authorities & food industry level)
Conduct Hazard Analysis - develop list of hazards and decide which one is most important at the moment
Identify critical control point - step or procedure at which control can be applied and a food safety hazard can be prevented, eliminated or reduced to acceptable levels
Establish critical limits - time-periods, temperature, ph, weight etc.
Monitor CCP - how, when measurements are taken. How frequently measurements are taken during the production?
Establish Corrective Action - what happens after. Team will identify steps to prevent potential hazards.
Verification - determine validity of HACCP plan.
Recordkeeping - record of what has happened. Monitoring of step 6.
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Why does food-borne illness emerge?
```
Globalisation of food supply
• Introduction of pathogens in new areas
• Increased traveling
• Changes in micro-organisms
• Change in human population
• Change in lifestyle
```
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Pathogenicity
* Adherence
* Toxin production
* Resistance to antimicrobial compounds
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Primary pathogen
Primary pathogens are capable of causing pathological changes associated with disease in a healthy individual
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Opportunistic pathogen
Opportunistic pathogens can only cause disease when the individual is compromised by a break in protective barriers or immunosuppression.
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Microscopy
Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye (objects that are not within the resolution range of the normal eye)
36
Culturing
Selective and Elective growth media
• Biochemical identification
• Mass Spectrometry
37
Molecular methods
```
• In contrast to microscopy and
culturing: the micro-organisms does
not have to be intact or to be growing
• Based on detection of parts of the
micro-organism: mostly their DNA or
RNA
```
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Detection priorities
Sensitivity
• Speed
• Costs
• Labour-intensity
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Control of source
- Closing food premises
- Removing implicated foods from the market
- Modifying a food production/preparation process
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Control of transmission
- Public advice
- Exclusion of infected persons from work and school
- Advice on personal hygiene
- Infection control precautions
- Protecting risk groups
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Preliminary assessment
- Consider whether or not the cases have the same illness (or different manifestations of the same disease).
- Determine whether there is a real outbreak by assessing the normal background activity of disease.
- Conduct in-depth interviews with initial cases.
- Collect clinical specimens from cases.
- Identify factors common to all or most cases.
- Conduct site investigation at implicated premises.
- Collect food specimens when appropriate.
- Formulate preliminary hypotheses.
- Initiate control measures as appropriate.
- Decide whether to convene a formal outbreak control team
- Make a decision about the need for further investigation.
42
Communication
- Consider the best routes of communication with colleagues, patients and the public.
- Ensure accuracy and timeliness. Include all those who need to know.
- Use mass media constructively
43
Descriptive epidemiology
- Establish case definitions for confirmed and probable cases.
- Identify as many cases as possible.
- Collect data from affected persons on a standardized questionnaire.
- Categorize cases by time, place and person.
- Determine who is at risk of becoming ill.
- Calculate attack rates.
44
Food and environmental investigations
- Inspect structural and operational hygiene in implicated food premises.
- Assess procedures undergone by a suspect food.
- Take appropriate food and environmental samples.
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Analysis and interpretation
- Review all existing data.
- Develop explanatory hypotheses.
- Carry out analytical studies to test hypotheses as required.
- Collect further clinical and food specimens for laboratory tests as required.
46
Control measures
- Control the source: animal, human or environmental.
- Control transmission.
- Protect persons at risk.
- Declare the outbreak over when the number of new cases has returned to background levels.
- Consider strengthening or instituting continuous surveillance
47
Further studies
- Conduct further analytical (case-control, cohort) studies.
- Conduct further food and microbiological investigations.
- Make recommendations for the prevention of recurrences of similar outbreaks.
- Determine remaining questions or areas for future research identified through this investigation.
- Share information with public health colleagues in order to promote awareness and possibly prevent similar outbreaks in the future.
48
Vulnerable groups
- Infants and young children: Immature immune system
- Pregnant women: Increased levels of progesterone →Downregulation of cell-mediated immunity → Increased susceptibility to infection by intracellular pathogens
- Older people:
• General decline in the body’s immune response + Decrease in stomach acid production
• Malnourished through poor diet → Adversely affected immune response
• Loss of sensory abilities → Difficulties in choosing and preparing food
→ Ageing population influence the increase in prevalence of foodborne disease
- Cancer patients, transplant patients receiving immunosuppressant drugs, patients with AIDS: Suppressed immune system
- infection dose → The amount of pathogen needed to cause an imbalance in the immune system. Low amount → our immune system kills it. When around 100 viruses with salmonella 100 000 needed to trigger the infection.
- Virulence → How strong the strain is. How intense/strong is the virus or the bacteria. So the pathogens or microbes ability to cause damage in the host.
49
EFSA
* Assesses and communicates all risks associated with the food chain
* Gives advice for policy and decision making
* Risk assessment (e.g. data collection, analysis, recommendations)
* Risk management (e.g. legislative measures, targets for reduction)
* Main role is to assess risks associated with the EU food chain, ensuring a high level of consumer protection and animal health: data collection monitoring risks making recommendations for prevention
50
The media
* Some general guidelines were put forward to keep the media on track and help avoid sensational reporting
* Anticipate on media needs
* Accept media interviews (or media will appoint their own experts)
* Know which media are reliable and concentrate on getting the story the them
* Adapt messages to different media
* Concentrate on facts and figures, but humanize the situation with metaphors and anecdotes
* Get professional media training
* Health professionals often distrust the media as being more interested in sensational story than in reporting the facts.
51
Directive 2003/99/EC
obligates all MSs collect data on outbreaks. The EFSA can use it to produce annual reports.
