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Flashcards in Surveillance Deck (41)
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Define monitoring

Continous efforts to collect data to detect changes or trends in the occourence of disease in order to inform decisisons


Define passive surveillance

Surveillance = monitoring with the view to intervene if prevalence rises above a certain theshold


Define incident

The first isolation and all subsequent isolations of the same serovar from an animal OR epidemiologiclaly distinct group of animals on a single premises wihtin a 30d period


How has salmonella incidence in humans and livestock changed over recent years?



Give an example of surveillance whre the threshold is 0



What is the target level of clinical mastitis?

30 cases/100 cows/year


How may surveillance be used?

- monitoring diseases deemed to be of importance
- checking for effectiveness of control measures
- if eradication is achieved, demonstrating freedom from infection


Give an example of a disease where the aim of surveillance is to prove freedom of disease



What was the first animal disease to be officiallly declared eradicated



What do farm level surveillance systems focus on?

- diseases controllable by the farmer
- focus on productivity
- rely on farm records


Give egs. of monitoring/surveillance objectives at a natinoal level

- demonstrate freedom from disease (eg. brucellosis)
- outbreak detection
- diseas control/eradication
- monitor zoonoses (eg. salmonella)
- pregress of hazard reduction programmes
- detect emerging disease


Give egs. of monitoring/surveillance objectives at an industrial level

- freedom from disease
- outbreaks
- define herd health status
- monitor production diseases
- monitor zoonoses and food bourne pathogens
- document acceptable risk levels


Give egs. of monitoring/surveillance objectives at a prodcer levle

- monitor production diseases
- outbreak detection
- assure freedom from food safetly hazard
- define herd/product status
- documnet aceptable risk levels


Give egs. of monitoring/surveillance objectives at a wildlife levle

establish disease status


How may cases be defined?

- clinical criteria: suspect cases that become confirmed following lab work (lab criteria added)
- epidemiological criteria eg. FMD control: farms defined as potental cases on the bases of location with repect to infected farms or dangerous contact with infected farms


What are the varying levels of disease prevalence?

- case
- outbreak
- epidemic
- pandemic


How are incidence and prevalence different?

- incidence = rate (no. new cases/ population at risk*time at risk)
- prevalence = proportion (no. existing cases/population at risk)


Define internal and external validity

- internal : measuring what is happening on farm, valid for that farm
- external validity: extrapolating to general population


What is the difference between active and passice monitoring or surveillance? Which is more susceptable to bias?

- passive: waiting, reliant on case reporting, awareness and motivation to report [most biased]
- active: searching, surveys, testing


How does systematic error differ from random error?

- systematic error: error due to the design, implementation or analysis of the surveillance programme
- random error: due to samping variation due to a random sampe of the popuation being studeied to make inferences about the whole popuation


Give 3 types of bias

- case detection: case ascertainment
- selection bias: in surveys if participation is voluntary, if not all famrs listed in sampking frame
- information bias: case definition, diagnositc tests


How may underrerporting skew surveillance statistics?

The "clinical iceberg" means deaths, severe disease and moderate disease [likely to be admitted to hosptial] but mild disease and sub-clinical infection not often reported so no cases actually ^ than recorded.


What is important regarding defining cases for epidemiology?

deifnition must be specific so that all cases are recorded correctly


What is important following detection of a case?

Dissemination of information quickly and efficiently to those who require it


How may lab tests introduce bias to results?

Differing sensitivity and specificity of lab tests


How may sampling introduce bias?

Picking a non random group of subjects


What are the 2 types of farm level monitoring and surveillance?

- statutory eg. TB, Brucella
- coluntary industry led eg. JD, BVD


Define a notifiable disease

statutory requirement to report suspicion of a clinical case of disease


Define a reportable disease

statutory requirement to report a lab confirmed isolation of organisms (ie. Salmonella nad Brucella) Under Zoonoses order 1989. Report made by lab that isolated the organism from animal dervied sample.


Who should notifiable disease be reported to?

- local animal health DVM
- now APHVLA