Chapter 4: Strategies of Prevention

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Strategies of Prevention

The scope and levels of prevention, mapped onto the natural history of disease

Prevention isn't one single action. It's a whole spectrum of interventions, each aimed at a different point along the natural history of disease you learned about in Topic 1. Lining the levels up against that timeline shows exactly what each one is trying to stop.

👆 Tap any segment below to reveal a real-world example of that level in action.

Before risk exists

Primordial Prevention

Change the underlying physical or social environment before risk factors even develop

Before exposure

Primary Prevention

Prevent exposure to the agent in the first place, stopping the process before it starts

Incubation / latency

Secondary Prevention

Screen and treat early, before symptoms appear, to stop progression

Clinical disease

Tertiary Prevention

Treat symptomatic illness to arrest, slow, or reverse its progress

After treatment

Quaternary Prevention

Avoid unnecessary or excessive medical intervention and its side effects

Tap a segment above to see a real-world example.

🚰 Try It: Matching Prevention to Level

A town discovers its well water is contaminated with bacteria that cause severe diarrhea. Which level of prevention does each response represent? Tap one to check yourself.

1. Installing a permanent water treatment system for the whole townReveal →
Level of prevention: Primary
2. Telling residents to boil water before drinking it until the well is fixedReveal →
Level of prevention: Primary
3. Testing residents for infection even before they feel sickReveal →
Level of prevention: Secondary
4. Giving IV fluids to residents who are already severely dehydrated from illnessReveal →
Level of prevention: Tertiary

Notice how the same outbreak can be attacked at several levels at once. A permanent treatment plant and a temporary boil-water notice are both primary prevention, because each one stops people from being exposed to the bacteria. Primordial prevention works even earlier, on the conditions that create risk factors in the first place.

✓ Check Yourself

Q1A country passes a law limiting salt and trans fats in packaged foods, so fewer people ever develop high blood pressure or high cholesterol. What level of prevention is this?

Primordial prevention: it changes conditions for the whole population so the risk factors (high blood pressure, high cholesterol) never develop in the first place. Compare: a water treatment plant that stops people from swallowing a germ is primary prevention, because it blocks exposure to an agent.