GI Outbreak investigation Flashcards
Discuss epidemioology of foodborne disease
- globally: 9% children vs 91% adults
- foodborne illnesses 38% children vs 62% adults
- foodborne deaths: 30 children vs 70% adults
- In Au
- 4.1 mil cases: 5100 non gastro, 36,000 sequalae
- 35000 hospitalisations
- 95 deaths
- 150 outbreaks
- 2.4 bil yearly: Camp –> E coli —> Noro –> Salmonella
- mainly due to lost productivity
ddefine epidemic outbreak and cluster
Epidemic
- The occurrence in a community or region of an illness… clearly in excess of normal expectancy
Outbreak
- An epidemic limited to a localised increase in the incidence of a disease
Cluster
- An unexplained increase of cases clustered in time, place or person
Discuss the clincial presentaon and development of gastro
Gastroenteritis
* Nausea, diarrhoea, vomiting, headache,
fever, blood in stool
* Wide range of agents – protozoa, bacteria,
bacterial intoxications, viruses
* Can include chemicals or poisoning
Can lead to extra-intestinal infection
* Listeriosis – meningitis or bacteraemia
* Salmonella Typhi – bacteraemia
* Hepatitis A – hepatitis
Development of Illness
Depends on
* Pathogen
* Incubation period
* Infectiousness of pathogen
* Dose of pathogen
* Immune status of individual
Higher incidence or worse outcome
* Young children
* Immunocompromised
* Pregnant
* Elderly
Many have sequelae
* Haemolytic uraemic syndrome
* Reactive arthritis
* Irritable bowel syndrome
Why is it necessary to investigate
- Understand source of illness
- Outbreak may be ongoing
- Not all food consumed - opportunities for recall
- Commercial food products
- Sign of food safety failure
- Identify how to prevent
- Identify common causes
- Surveillance of outbreaks
- Preventable cause of disease
Define surveillance
“Ongoing systematic collection, analysis, and
interpretation of data about foodborne diseases to inform implementation and evaluation of disease prevention, and dissemination of data to those who
need to know to prevent and control disease”
what are the aims of surveillance
- Monitor trends in foodborne disease
- Detect clusters and outbreaks of disease
Describe reporting
> 200 Diseases
12 notifiable nationally
* States and territories have additional surveillance
* Outbreaks, if suspected, must be reported
S&T, OzFoodNet
* Local, National & International
Laboratory based
Characterisation critical
how much do waterborne outbreaks contribute?
Drinking water highly regulated
- <1% outbreaks waterborne
* 4:5 attributed to recreational water
* 1:5 from drinking water
Outbreaks and untreated water supplies
* Tank water, bore water
Recreational water outbreaks
* Cryptosporidium – swimming pools
DESCRIBE THE makeup of person to perosn outbreaks
Mainly viral
* Norovirus & Rotavirus
Notifiable
* Gastroenteritis in an institution (NSW measure; for aged-care centres or prisons)
* Cluster of gastrointestinal illness
Aim of reporting outbreaks in institutions
* Determine if it is foodborne or person-to person
* Advice on infection control issues if person-to- person
Main intervention
* Regular handwashing (preferably soap & water)
* Cleaning and disinfection
* Exclusion and cohorting of ill people
Describe zoonotoic outbreaks
Relatively rare in Australia
Groups at increased risk
* Children
* Immunocompromised
Operator actions to reduce risk
* Animal wellbeing
* Hand washing
* Separate animal areas and eating areas
* Waste disposal
* Information to visitors
* Cleaning
List the ten steps for investigating zoonotic outbreaks
- Prepare for field work
- Confirm the diagnosis
- Determine existence of an epidemic
- Identify & count cases
- Orient data: Time, Place & Person
- Consider if control measures possible
- Develop & test hypotheses
- Plan more systematic study
- Implement & evaluate control measures
- Communicate
list the tools of investigation
- lab
- food water and clinical testing
- identify etiology
- testing foods and waters
- sequencing if possible
- epidemiology
- good descriptive analysis: quick and clean
- right study design
- rapid reporting
- food safety
- trace all foods
- collect samples
- identify and fix problems
Describe interview and intial investigation process
- Conduct 5-10 case interviews
- Demographics (i.e. m:f, age) & clinical manifestations
- Extensive history – food, water, animals
- Collect clinical specimens
- Descriptive epidemiology of cases
- Identify agent/pathogen
- Follow guidelines
- Directs type of investigation
- Guides control measures
DESCRIBE symptom profiles
Determine from 5–10 interviews
Aetiological Clues
* Possible vehicles
* Population affected
* Seasonality
Directs Investigation
* Case definition
* Testing
* Intervention & control
distinguish between viral bacterial and bacterial toxin syndromes
- syndromes are usually detected before the causative agent itself
- obtained from a series of patients with related symptoms
- viral tends to have shorter incubation than bacterial, although some overlap
- bacterial tends to be less associated with vomiting and more associated with fever, cramps and bloody stool
- bacterial toxin does not constitute a heavy burden on the health care system due to its relatively self-limiting nature
