Investigating an Outbreak Flashcards

1
Q

what is an outbreak?

A

outbreak/epidemic exists when there are more cases of a particular disease than expected in a given area or among a specific group of people over a particular period of time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

why do we investigate an outbreak? (6)

A
  1. to control and prevent disease
  2. to determine the severity and risk to others
  3. for research opportunities and to gain additional knowledge
  4. training opportunities
  5. program considerations (training and prevention)
  6. public, political, or legal concerns
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are the 7 steps of investigating an outbreak?

A
  1. prepare for field work
  2. verify outbreak
  3. plot epidemic curve
  4. calculate attack rates
  5. determine source of epidemic
  6. recommend control measures
  7. follow up
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what are the 5 things that happen in step 1 of investigating an outbreak (preparing for field work)?

A
  1. research what is known about the disease or symptoms
  2. learn about demographics and customs of local population
  3. make admin and travel arrangements
  4. build your team with clear delineation of responsibilities and assignments
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are the 4 things that happen in step 2 of investigating an outbreak (verifying outbreak)?

A
  1. establish a case definition that is non-ambiguous with clinical/diagnostic verification if possible with person/place/time descriptions
  2. identify and count cases of illness
  3. determine if disease is above endemic levels or if looking at a different disease with similar symptom
  4. develop and administer a questionnaire to determine demographics, behaviors, and exposures
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

how is an epidemic curve plotted?

A

number of cases on the y axis by their date or time of onset (x axis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what does the overall pattern of an epidemic curve tell you?

A

the increase, peak, and decrease can tell type of epidemic and incubation period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what can outliers of an epidemic curve tell you?

A

if a case is unrelated, early or late exposures, index case, secondary cases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

describe the epidemic curve of a vector borne disease (3)

A
  1. starts slowly (climate effects can modify)
  2. the time between the 1st case and peak is comprable to incubation period
  3. slow tail, will rise again or repeat until run out of susceptible people
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

describe the epidemic curve of a point source epidemic

A

large population exposed over a short period of time so high peak at beginning and then tapers off; most common form of transmission for food-borne disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

describe the epidemic curve of a continuing common source or intermittent exposure epidemic

A

several peaks, cannot isolate incubation period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

give an example of a point source epidemic

A

legionnaire’s disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

give an example of continuing common source or intermittent exposure epidemic

A

cholera

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

describe the 3 steps in step 4 of investigating an outbreak (calculate attack rates)

A
  1. calculate attack rate for each possible risk factor
  2. if there is an obvious commonality for the outbreak, calculate attack rates based on exposure status (a community picnic, then later you can calculate this to individual items at the picnic)
  3. if there is no obvious commonality for the outbreak, calculate attack rates based on specific demographic variables
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

describe step 5 of investigating an outbreak (determining source of epidemic)

A

attack rates can point statistically to the factor most closely associated with becoming a case, but it may require more than one risk factor to become a case, so ask if there are case that are NOT associated with your source (like malaria not from a mosquito)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

describe 3 things that happen in step 6 of investigating an outbreak (recommending control measures)

A
  1. recommend measures that would serve to reduce transmission (toss potato salad)
  2. these recs will be considered by public health personnel
  3. then long-term measures will be provided to prevent future outbreaks (here is how to store the potato salad)
17
Q

describe 4 things that happen in step 7 of investigating an outbreak (following up)

A
  1. follow up to determine the effects of the intervention measures incorporated
  2. meet with your team to critique and refine your response
  3. identify what works well and what did not
  4. communicate the specifics on the outbreal for study and educational applications
18
Q

define a foodborne disease outbreak

A

an incident in which two or more persons experience a similar illness after ingestion of a common food and epidemiologic analysis implicated the food as the source of the illness

19
Q

define intoxication as related to foodborne illness

A

ingestion of foods with toxicants of certain plants and animals, metabolic products formed and excreted by microbes while they multiply, or poisonous substances introduced during production, processing, transportation, or storage of food

20
Q

define infections as related to foodborne illness

A

caused by the entrance of pathogenic microbes into the body and the reaction of the body tissues to their presence or to the toxins they generate within the body

21
Q

give 4 rules of thumb, but not laws, related to foodborne illnesses

A
  1. intoxicants are rapid onset, no fever
  2. toxins in the stomach produce vomiting
  3. toxins in the intestines produce diarrhea
  4. infections produce fever
22
Q

what are the 3 types of foodborne contamination? give examples of each

A
  1. physical: glass, metal fragments, dirt, bone
  2. chemical: pesticides, cleaning compounds, poisonous metals (lead), additives and preservatives
  3. biological: bacteria, virus, fungi, protists, yeast, mold, parasites, insects, rodents, poisonous fish and plants
23
Q

what are the 6 bacterial requirements?

A
  1. food
  2. water
  3. pH
  4. temperature
  5. time
  6. oxygen
24
Q

what kind of food do most bacteria require?

A

what we consider to be potentially hazardous food such as milk or milk products, eggs, meat, poulty, fish, shellfish (anything high protein and moist)

25
Q

describe bacterial water requirement

A

most bacteria require moisture to thrive

26
Q

what is Aw?

A

water activity: the amount of water available in food

27
Q

what is the lowest Aw where bacteria can grow?

A

0.85

28
Q

what is the Aw range of most potentially hazardous foods?

A

0.97-0.99

29
Q

at what pH range do most bacteria grow best?

A

neutral or slightly acidic (4.6-7.0)

30
Q

what is the danger zone of temperature for foods (where most bacterial growth occurs)?

A

45-145 degrees F

31
Q

describe how time relates to temperature for bacterial growth in foods

A

do not let food stay in the danger zone of temperature for more than 4 hours!!!

32
Q

do all bacteria require the same amount of oxygen?

A

no; can be aerobic, anaerobic, or facultative anaerobes

33
Q

what are the 6 major causes of foodborne disease?

A
  1. improper cooling
  2. improper cooking
  3. improper reheating
  4. improper holding temperature
  5. cross contamination
  6. infected food handlers, poor employee hygiene