NSO Biology – Principles of Prevention and Treatment
Topic: Principles of Prevention and Treatment
Audience: High‑school students preparing for Science Olympiad
Format: Markdown study notes – simple explanation, key points, worked example, quick revision summary
1. Simple Explanation
Prevention means stopping a disease or health problem from occurring or spreading.
Treatment means curing the disease or reducing its severity once it has already started.
In biology the two are closely linked: good prevention strategies reduce the need for expensive or risky treatments, and effective treatments can sometimes become preventive (e.g., treating a viral infection early to stop its transmission).
2. Key Points
| Category | What it Means | How It’s Done | Example |
|---|---|---|---|
| Primary Prevention | Stops disease before it starts. | Vaccinations, hygiene, healthy lifestyle, environmental controls. | Influenza vaccine, wearing masks. |
| Secondary Prevention | Detects disease early, often before symptoms. | Screening tests, early diagnostics, routine check‑ups. | Mammography for breast cancer, blood pressure checks. |
| Tertiary Prevention | Reduces complications after disease onset. | Rehabilitation, palliative care, lifestyle changes. | Physiotherapy after stroke. |
| Antimicrobial Stewardship | Uses antibiotics/antivirals wisely to prevent resistance. | Narrow‑spectrum drugs, proper dosing, discontinuation when finished. | Prescribing azithromycin only for confirmed bacterial infections. |
| Vaccination Principles | Induce immunity through exposure to a weakened or inactivated pathogen. | Live‑attenuated, inactivated, subunit, conjugate, mRNA vaccines. | HPV vaccine protects against cervical cancer. |
| Infection Control | Reduces spread in healthcare and community settings. | Hand hygiene, PPE, sterilization, isolation. | Hand‑washing protocol in hospitals. |
| Screening & Early Detection | Identifies at‑risk individuals before disease manifests. | Risk‑factor assessment, lab tests, imaging. | Colonoscopy for people >50 yrs. |
| Treatment Hierarchy | From least to most invasive. | Supportive care → pharmacotherapy → surgery → transplant → palliative. | Treat bacterial pneumonia first with antibiotics, then oxygen if needed. |
| Combination Therapy | Uses two or more drugs to target different mechanisms. | Reduces resistance, improves efficacy. | HIV therapy = NRTI + NNRTI + PI. |
| Patient Education | Ensures compliance and self‑management. | Clear instructions, counseling, follow‑up. | Diabetes education on insulin use. |
2.1 Prevention in Infectious Diseases
| Strategy | Mechanism | Benefits |
|---|---|---|
| Vaccination | Induces specific immune memory | Prevents infection, reduces transmission |
| Hygiene | Removes/neutralizes pathogens | Lowers community spread |
| Antimicrobial Stewardship | Minimizes resistance | Preserves drug efficacy |
| Quarantine & Isolation | Segregates infected individuals | Breaks transmission chains |
| Screening | Detects asymptomatic carriers | Early treatment, stops spread |
2.2 Prevention in Non‑Communicable Diseases
| Risk Factor | Prevention Strategy | Outcome |
|---|---|---|
| Smoking | Cessation programs, nicotine replacement | Decreases lung cancer, COPD |
| Obesity | Dietary counseling, exercise | Reduces diabetes, hypertension |
| Excessive sun exposure | Sunscreen, protective clothing | Lowers skin cancer risk |
| Alcohol abuse | Counseling, support groups | Reduces liver disease, cancers |
3. Worked Example
Scenario: A 30‑year‑old woman presents with a sore throat, low‑grade fever, and swollen lymph nodes. She works in a daycare and has close contact with infants.
Step‑by‑Step Prevention & Treatment Plan
| Step | Preventive/Treatment Action | Rationale |
|---|---|---|
| 1. Epidemiologic Assessment | Obtain history of close contact with children; ask about recent illnesses. | Infants are common carriers of Streptococcus pyogenes (strep throat). |
| 2. Primary Prevention | Ensure she has received the Tdap vaccine (protects against pertussis). | Prevents pertussis, a serious respiratory disease in infants. |
| 3. Secondary Prevention | Rapid antigen detection test (RADT) for strep throat. | Early detection allows prompt treatment, reduces complications. |
| 4. Treatment | If RADT positive, prescribe penicillin V 500 mg BID for 10 days. | Penicillin is first‑line for strep; short course limits resistance. |
| 5. Antibiotic Stewardship | Only prescribe antibiotics if test is positive; avoid macrolides unless allergic. | Reduces unnecessary antibiotic use, limits resistance. |
| 6. Tertiary Prevention | Counsel on completing the full course and monitoring for rheumatic fever. | Prevents long‑term heart damage. |
| 7. Infection Control | Advise hand hygiene, covering cough, and avoiding close contact with infants until 24 h after antibiotics start. | Breaks transmission chain to vulnerable infants. |
| 8. Follow‑Up | Re‑evaluate if symptoms persist after 48 h. | Ensures efficacy and checks for complications. |
Outcome:
- Disease prevented in infants via vaccination.
- Prompt detection and treatment of strep throat reduces morbidity and complications.
- Patient educated on