Community Medicine
What Community Medicine tests
Community medicine in Part I covers prevention, primary health care, maternal and child health services, environmental health and outbreak response. The exam expects population-level thinking: who is at risk, which intervention reaches most people, and how to measure whether it worked.
Core rules
- Levels of prevention: primordial (risk-factor elimination), primary (before disease occurs), secondary (early detection or screening), tertiary (limiting disability), quaternary (avoiding overmedicalisation).
- Screening criteria: an important disease, an accepted treatment, a detectable latent stage, a suitable test with acceptable sensitivity and specificity, cost-effectiveness, and a system for following up positive results.
- Cold chain: most vaccines are kept at +2 to +8 °C; freeze-sensitive vaccines such as DTP, hepatitis B, Hib and IPV must never freeze; check the vaccine vial monitor before use.
- Outbreak investigation: confirm the diagnosis, define and count cases using a case definition and line listing, describe by person, place and time, generate hypotheses, test them with a cohort or case-control study, control the source, then communicate findings.
- Notifiable diseases must be reported promptly to the Ministry of Health so surveillance can trigger a response.
Worked example
A village reports 40 cases of watery diarrhoea in 5 days. Reason: first agree a case definition and build a line list, then plot an epidemic curve by day and map cases by household and water source. Inspect the water supply and test chlorine residual. Institute chlorination, safe storage, oral rehydration and hygiene education while continuing surveillance. A case-control study comparing water source between cases and controls would test the hypothesis of a contaminated well.
Traps
Confusing primary with secondary prevention; treating screening as harmless despite false positives and overdiagnosis; waiting for laboratory confirmation when immediate notification is legally required; neglecting environmental investigation while focusing only on treatment.