Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
17 Cards in this Set
- Front
- Back
|
What does a "LINE LISTING" include?
|
-LISTING OF ALL ANIMAL ON PREMISES-
-AGE -BREED -GENDER -WHETHER ILL OR NOT -IF ILL, DATE OF ONSET -SIGNS -TEST RESULTS ***ensures you examine ALL animals and collect information in an objective manner*** |
|
|
How would you CHARACTERIZE AN EPIDEMIC?
|
1.TIME- identify INDEX CASE; draw and characterize the EPIDEMIC CURVE; estimate PERIOD OF EXPOSURE
2. PLACE- look for geographic clustering, unusual distribution of cases; may use MAPS, RATES by barn, pasture, cage, building, etc. 3. HOST- what group are at risk? apparently unaffected?; RATES by age, gender, species, production status, duration of residence, vax. status, etc. 4. MANAGEMENT GROUP- RATES by different management groups Differences among or b/w the groups (by host type, place, etc.) provide data to TEST certain hypotheses or LEAD to new ones. |
|
|
What are the things involved in the EPIDEMIOLOGIAL TRIAD?
|
HOST, AGENT, ENVIRONMENT
MANANGEMENT Disease occurs as a consequence of a COMPLEX INTERPLAY of HOST and AGENT characteristics, ENVRIONMENTAL influences and the IMPACT of MANAGEMENT PRACTICES on EACH of these components. |
|
|
ENDEMIC DISEASE
|
REGULARY and CONTINUOUSLY PRESENT.
LEVEL- usual frequency of disease occurs VARIES BY: disease, species, geographic location, and type of population Ex. Endemic level of persistent viremia with FeLV in stray cats is <5%, but in INFECTED CATTERIeS, its 30%. |
|
|
EPIDEMIC (used interchangeably with OUTBREAK!)
|
Epidemic exists when the frequency of disease occuring is CLEARLY IN EXCESS OF ITS EXPECTED FREQUENCY based on previous experience.
STATISTICALLY- OBSERVED LEVEL IS GREATER THAN 2 STANDARD DEVIATIONS ABOVE THE AVERAGE LEVEL USUALLY OBSERVED. |
|
|
EPIDEMIC CURVE
|
Generated by plotting the DISTRIBUTION OF NEW CASES BY TIME OF ONSET.
Shape of curve and time scale are influenced by: 1. INCUBATION PERIOD OF AGENT 2. % SUSCEPTIBLE ANIMALS 3. INFECTIVITY OF AGENT 4. POPULATION DENSITY |
|
|
What are the TWO basic types of EPIDEMICS?
|
COMMON SOURCE
PROPAGATING |
|
|
What are the TWO types of COMMON SOURCE epidemics?
|
POINT SOURCE: resulting from exposure to common source of infection at one point in time.
ex. all animal fed the same lot of contaminated food. EPIDEMIC CURVE CHARACTERIZED BY: 1. Abrupt rise and fall in number of cases 2. cases occur roughly w/in the range of the known incubation period of the agent CONTINUING COMMON SOURCE (CONTINUING EXPOSURE, MULTIPLE EVENT): resulting from exposure to a common source of infection/ intoxication that continues for a "lengthy" period of time. ex. cattle exposed to PBB's for months before the feed contamination was identified. EPIDEMIC CURVE CHARACTERIZED BY: 1. abrupt onset 2. continuing high levels of disease until the source is removed or most animals are affected. Extends BEYOND RANGE OF INCUBATION PERIOD for the suspected agent. |
|
|
What are the DURATION OF COMMON SOURCE EPIDEMICS INFLUENCED BY?
|
1. number of susceptible animals that are exposed to a source of infection and become infected
2. period of time over which the susceptible animals are exposed to the source 3. minimum and maximum incubation periods of the disease (for point common source) |
|
|
How do you determine the probable period of exposure in a COMMON POINT SOURCE OUTBREAK?
|
1. clinical presentation and PE's of animals involved in the outbreak often leads to a list of differential diagnoses.
METHOD 1: estimating time of exposure; indentify the date of the peak kof the epidemic curve and one incubation period back in time is counted. METHOD 2: count back the minimum incubation period from the first case that occured and note the date; then count back the maximum incubation period from the last case and note that date. The time interval b/w the 2 dates is the period w/in which the exposure occured. |
|
|
What are PROPAGATING OUTBREAKS?
|
characterized by animal to animal transmission of the agent
1. less abrupt onsets 2. usually occur over a longer period of time, spanning many incubation periods as compared to common source outbreaks |
|
|
What is the definition of THRESHOLD LEVEL?
|
Minimum level of susceptible animals that is necessary for a propagated diesase to being.
|
|
|
What is the definition of HERD IMMUNITY?
|
Resistance of a group of animals to invasion and spread of an infectious agent based on the immunity of a high proportion of individual members of the group.
The degree of herd immunity necessary to prevent the development of an epidemic varies by diease. |
|
|
Define INDEX CASE.
|
Case that bring the outbreak to the attention of investigators.
USUALLY the FIRST CASE. |
|
|
What is the PRIMARY OBJECTIVE of an OUTBREAK INVESTIGATION?
|
IDENTIFY and IMPLEMENT EFFECTIVE CONTROL MEASURES TO ELIMINATE THIS EPIDEMIC AND TO PREVENT SIMILAR REOCCURENCES in the future.
|
|
|
What are the SUBOBJECTIVES in an OUTBREAK INVESTIGATION?
|
1. Cause(s) must be determined
2. Source and mode of transmission must be identified 3. Extent (numbers & types of animals affected) must be identified Can be achieved using different approaches to the investigation. GOAL= develop a SYSTEMATIC APPROACH!! |
|
|
What are the ten recommended steps in INVESTIGATING AN OUTBREAK?
|
1. Prepare for field work
2. Confirm the existence of an epidemic or outbreak 3. Establish or verify the DIAGNOSIS 4. Define and identify cases -establish a case def. -identify and count cases 5. Characterize the outbreak in terms of: -time -place -host -management practices 6. Formulate hypotheses 7. Evaluate the hypotheses 8. If necessary, refine or develop new hypotheses and evaluate 9. Develop and implement CONTROL and PREVENTION measures 10. Communicate findings and conclusions |
