Lecture 10 - Gastroenteritis Epidemiology Flashcards Preview

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Flashcards in Lecture 10 - Gastroenteritis Epidemiology Deck (37):
0

Differentiate between food-borne illness and gastrointestinal disease

Some food borne pathogens cause disease that is not gastroenteritis:
- Creuzfeld Jacob
- Hepatitis A

Some gastrointestinal disease is not food borne:
- Person to person
- Petting zoos
- Water borne

1

In general, which pathogens cause vomiting, and which don't?

Emetic:
- B. cereus
- S. aureus
- rotavirus
- norovirus

Non-emetic:
- extracellular
- invasive
- C. perfringens

2

Which bacteria can cause dysentery in some cases?

E. coli
Shigella spp.

3

What are the most common agents of gastroenteritis?

Campylobacter
C. perfringens (to a lesser degree)

4

What are the most common agents of gastroenteritis in Australia?

Campylobacter
Salmonella
Giardia

C. perfringens (to a lesser degree)

5

Describe the stages of the pyramid

7 steps

- exposure
- person falls ill
- person seeks care
- specimen obtained
- test performed
- confirmation of infection
- reported to health department

6

What percent of cases of gastro are reported to the health department?

1%

7

How many cases of gastro can an Australian expect to have per year?

0.92 --> one case a year

8

What is the impact of gastroenteritis on Australia?

Many lost days of work
Many trips to the doctor
Financial burden on Government, Businesses, Healthcare
Deaths

9

What percent of gastroenteritis cases are food-borne?

Around 32%

10

How many hospitalisation are there per year due to gastro?

What related illnesses also lead to hospitalisations?

Around 40,000

Reactive arthritis, septicaemia

11

How many deaths per year in Australia due to Gastroenteritis?

What are these usually due to?

200

Haemolytic Uraemic syndrome, infection of the elderly

12

Explain what happened in London 1848

Many people were dying due to dehydration
No understanding of micro-organisms
Deaths concentrated around a water pump in Broad street

13

How did John Snow figure out the source of the disease?

Mapped out the deaths --> concentrated around a water pump in Broad street

One family had a case of Cholera -- this was the index case. The infected faeces in the cess pit under the house.
Cess pit leaked into the water pipe

Everyone in the area came to get their water from the Broad street pump

When the handle was broken off --> no more cases

14

What is the index case?

The first case of the disease

15

What is the definition of epidemiology?

Study of occurence, spread and control of disease

16

Compare the terms epidemic, pandemic and endemic

Endemic: when a disease is present at low levels, at all times, within a population

Epidemic: rapid increase in number of cases in a country

Pandemic: rapid increases in number of cases across the world

17

What are some situations in which a point source accounts for infection?

Wedding
BBQ

Group of diverse people come together and share a meal

Rapid number of cases, then it dies out

18

What are the ways we can describe the time of the outbreak?

• Point source
• Continuing source

19

What are the features of a continuing source?

Give an example

Relatively slow to peak and decline.
The source of infection is present over a long period of time

Eg. Hep A from contaminated oyesters

20

What type of graph is an epidemic curve?

Histogram plotting the number of cases occurring on a particular day / week

21

In a case of Person to person spread, what does the epidemic curve look like?

Increase in number of cases with each generation

22

How can 'person' be described in an outbreak?

The vulnerable demographics

23

How can 'place' be described in an outbreak?

• Map with dots representing the cases
• rates per year in a population

24

How may 'Pathogen' be described in an outbreak?

PFGE: pulse field gel electrophoresis

25

Why are Case-Control studies used?

The determine the source

26

Describe the case of gastroenteritis in Ohio teenagers

Salmonella muenchen isolated from affected individuals

41% of affected households contained young adults

Questioning regarding drug use --> Marajuana source

27

Describe the case of the Chinese Restaurant cases of gastro

• Many people who all ate at a particular restaurant came down with gastro

• Investigators asked everyone what they ate, and managed to track it back to deep fried ice cream

• Same Salmonella phage type isolated from faces of infected people and ice cream batter

28

Which organisations deal with food-Bourne illness?

State Health Departments

OzFoodNet

WHO

HACCP

29

What are some challenges in control of Gastro and food-Bourne illnesses

• Modern eating habits
• Globalisation
• Antibiotic use in animals
• Complexity of food handling

30

Which demographic worldwide is most affected by diarrhoeal disease

99% of deaths due to diarrhoeal disease are in non-industrialised countries

32

How many deaths per year due to diarrhoea?

1.8 million

33

What is the aim of analytic epidemiology?

To find the source of the outbreak

34

Which pathogen is the least common causal agents of gastro in Australia?

Vibrio family

35

What are the Principles of Outbreak investigation?

1. Describe the outbreak
2. Develop and test a hypothesis
3. Intervene to control outbreak
4. Prevent future outbreak

36

What general things do we need to describe about the outbreak?

• Place
• Time
• Person
• Pathogen

37

Name two cases of analytic epidemiology

• Chinese restaurant outbreak
• Ohio outbreak