Detecting Disease in a Population Flashcards
what are 3 considerations for diagnostic testing of an individual
- pathogen of concern
-hx, CS
-differential list - available tests: how those tests are interpreted
- feasibility of testing:
-cost, ability to collect samples
what are the general types of tests?
- molecular or genetic material: PCR, RNA seq
- immunoassays: antigen/antibody, serology, ELISA, SNAP, etc.
- chemical/minerals: heavy metals, renal calculi, selenium
- organic compounds: vitamins, toxins, mass spec, chromatography
- live/viable things: virus isolation, culture and sensitivity
- pathology tests: cytology, biopsy, necropsy
which tests directly assess for a pathogen? which test for the secondary effect of the infection/condition?
Directly assess for pathogen:
1. PCR: genetic material
2. antigen-binding immunoassays
3. culture/viral isolation
4. parasitology
secondary effect:
1. antibody response- DELAYED
2. indicative pathology/biochem
3. clinical picture
what are things to consider when developing a diagnostic plan?
- goal:
-determine extent of outbreak
-surveillance: catch outbreaks early
-eradication programs - population characteristics;
-size, ages, housing, vaccination
-at risk population
-housing factors that could impact transmission - pathogens of concern
- available tests: how they are interpreted too
- feasibility of testing: cost and ability to collect samples (are animals readily available?)
describe a surveillance program
surveillance = data collection + regular intervals + plan of action
general considerations:
1. rigor: minimal vs comprehensive
2. types and considerations:
-active vs. passive
-lab based vs syndromic
-whole population vs targeted
describe active surveillance
- conducted to find outcome or indicators of interest as part of a formal surveillance effort/program
- pros:
-primary data source
-accurate and complete
-rep of a larger population - cons: expensive and time consuming
describe passive surveillance
- uses info and/or samples collected for another purpose
- pros:
-easy, inexpensive, access to samples - cons:
-secondary data
-limited by data quality
-may not be representative of larger population
-subject to under reporting
describe laboratory based surveillance
- rely on diagnostic testing for definitive diagnosis
- pros: def dx
- cons: expensive and time consuming
describe syndrome surveillance
- focuses on non-specific indicators of disease that are present before definitive diagnosis
pros: easy and inexpensive
cons: no lab dx, non-specific indicators of disease
describe targeted/risk-based surveillance
- focused efforts on previously identified hazards or known risk factors for a particular outcome
pros:
-accurate
-focused on population of concern
-helpful in capturing previously identified risks
cons:
-time consuming, expensive
-not all inclusive
-only effective for known risks (need a framework)
-unlikely to ID emerging diseases unless designed for that purpose
describe non-probability sampling versus probability sampling
non-probability sampling: based on selection criteria
-consecutive sample: selected based on availability
-convenience sample: selected based on ease of access
-judgement sample: selected based on researcher’s judgement of who is best suited
probability sampling:
-simple random sample
-stratified random sample
-cluster sampling
-multistage sampling (2 stage cluster sampling)
describe a simple random sample
each individual in the population has an equal and known probability of being selected for the sample
ex. randomly select 10% of the population
describe stratified sampling
subgroups of the population are sampled independently
ex. randomly select 3 from each group or strata in a population
describe cluster sampling
the sampling unit is a group rather than an individual
ex. randomly select 3 groups in a population
describe multistage sampling (2 stage cluster sampling)
randomly select 3 groups in a population then randomly select 3 individuals from each group
