Community Health (Community Health Nursing)
What this domain tests
This domain covers levels of prevention, epidemiology measures, the rural health infrastructure, national health programmes, family planning, the cold chain, maternal and child health indicators, and screening-test interpretation.
Core rules
- Levels of prevention: primordial and primary (immunisation, health education, sanitation), secondary (screening, early diagnosis, treatment), tertiary (rehabilitation, disability limitation).
- Population norms: sub-centre one per 5,000 in plains and 3,000 in hilly or tribal areas; PHC one per 30,000 plains and 20,000 hilly; CHC one per 80,000–1,20,000.
- Epidemiology: incidence counts new cases over a period; prevalence counts all existing cases at a point. Attack rate is used in outbreaks.
- Vital statistics: infant mortality rate = infant deaths under 1 year per 1,000 live births in the same year; maternal mortality ratio = maternal deaths per 1,00,000 live births.
- Cold chain: OPV and measles vaccines at −20 °C to −25 °C in deep freezers; most other vaccines at 2–8 °C; never freeze hepatitis B, DPT or pentavalent.
- Screening tests: sensitivity detects true positives; specificity detects true negatives; a highly sensitive test suits screening, a highly specific test confirms.
Worked example
A screening test is applied to 200 people, of whom 80 truly have the disease. It correctly identifies 72 of them. Sensitivity = 72 ÷ 80 × 100 = 90%. If the test wrongly labelled 24 healthy people as positive, specificity would be (120 − 24) ÷ 120 × 100 = 80%. High sensitivity means few false negatives.
Traps that cost marks
- Confusing incidence with prevalence in a chronic-disease question.
- Classifying immunisation as secondary prevention.
- Freezing pentavalent or hepatitis B vaccine, which destroys potency.
- Swapping sensitivity (rules out disease) with specificity (rules in disease).