Outbreak/HPV Flashcards
How to define an outbreak?
Any unusual or unexpected increase in the number of cases of a particular disease than would normally be expected in a given area, or among a specific group of people
- Two or more cases who have vomiting or diarrhoea over a 24-hour period –> unusual/unexpected in the area
- Within 72 hours of each other (in care facility)
What are some observational studies?
do not interfere with participants, natural progression, confounders are not controlled
Cohort study + case control
What is cohort study?
observational studies
o less commonly done in outbreak o Retrospective exposure and outcomes already happened --> whether exposure to risk factor is associated with statistically significant difference in outcome development conduct on data that already exists o Perspective People are recruited into cohort usually by geography or occupation Study follows them for defined period to assess proportion that develop the disease of interest Look at relative risk Advantages - Can establish risks directly - Assess multiple disease Disadvantages - Expensive - Longer/harder to conduct - Not good for rare disease - Not good for disease with long latency periods
What is case control? observational studies
Identify cases Select control group: matched for age, sex, location such as neighbours, community members Compare exposures among cases and control Use odds ratio and confidence intervals Advantages - Cheaper, quick - Disease with long latency period - Multiple exposures - Rare disease Disadvantages - Only one disease - More prone to bias - Cannot establish risk
What is experimental study?
Randomised controlled trial
- Eligible people are randomly assigned to groups
- One group received intervention (such as a new drug) while control group receive nothing/placebo
- Gold standard for producing reliable evidence as there is little confounders, however, sometimes due to ethical issues, only observational studies can be conducted
How is odds ratio being calculated?
A/C divide B/D
disease exposed/disease unexposed
healthy exposed/healthy unexposed
- Quantifies the strength of association b/w 2 events
- > 1: disease and exposure are associated: compared with the absence of exposure, the presence of exposure raises the odds of getting the disease
- <1: negatively associated, the presence of exposure reduced the odds of getting the disease
- 1: the same in either the presence or absence of exposure
What is confidence intervals?
- The likelihood of true values
- If it DOESN’T CROSS 1, 95% confident that the data doesn’t occur due to chance/variables, so it is significant –> odds ratio is significant
What are some pathogens cause gastro?
Toxin –> rapid onset around 1-8 hours –> staphylococcus aureus toxins
campylobacter C.difficile giardia norovirus (12-48 hours) salmonella (6-72 hrs) shigella (1-3 days)
How to conduct an investigation?
- determine existence of an outbreak: background rate in increased
- confirm the diagnosis
- identify and count cases: a condition of a set of symptoms + gather cases from different sources
- tabulate data in terms of time (onset), place (gatherings, residence) and person (demographics)
- immediate controls (give prophylactics to people at risk)
- test hypotheses: causative agents, transmission, original sources using case-control or cohort studies
- prevention and control measures: premise lockdown, disinfection
- communicate: spokesperson, reports
Which 2 HPV virus causes cancer?
HPV 16 –> squamous cell carcinoma
HPV 18 –> adenocarcinoma
What cancers does HPV cause?
cervical anal vulvar penile oropharyngeal
How is HPV transmitted?
sexual contacts and use of sex toys or other objects.
Condoms and dental dams can lower the chance of HPV transmission but do not prevent it completely.
When should HPV vaccine give?
HPV vaccination offers the most protection when given at ages 9-12, up to 26
Adults between the ages of 27 and 45 benefit less from the vaccine because they are more likely to have been exposed to HPV already. Therefore vaccination is not routinely recommended for people in this age group.
cervical screening program
Every woman aged 25–74 who has ever been sexually active should have a Cervical Screening Test every five years.
symptomatic women may have a cervical sample taken at any time, regardless of their age or screening history --> have a co-test (LBC and HPV). symptoms - pelvic pain - pain during sex - mucoid, purulent vaginal discharge - abnormal vaginal bleeding, menorrhagia
Cervix epithelium
Upper cervix: simple columnar epithelium
lower cervix: stratified squamous epithelium
Cancer in
- transformation zone: squamous metaplasia
