Chart — Infection Control
Latent vs Active Tuberculosis Comparison
The whole of TB triage hangs on one distinction: is the infection walled off and silent (latent), or replicating and contagious (active)? It decides whether the patient needs an isolation room, whether contacts are at risk, and which treatment they get.
Educational use only. Testing interpretation, treatment regimens, and isolation discontinuation are provider- and public-health-directed; follow current guidance. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
Latent vs Active Side by Side
| Feature | Latent TB Infection | Active TB Disease |
|---|---|---|
| Symptoms | None — feels well | Cough (often 3+ weeks), hemoptysis, night sweats, fever, weight loss, fatigue |
| Infectious? | No — cannot spread TB to others | Yes — spreads via airborne droplet nuclei |
| TB skin test (TST) / IGRA | Positive | Usually positive |
| Chest X-ray | Normal (or old calcified granuloma) | Abnormal — infiltrates, cavitation, often upper lobes |
| Sputum smear/culture | Negative | Positive for acid-fast bacilli / M. tuberculosis |
| Isolation | Not required | Airborne precautions: negative-pressure room, N95, mask the patient for transport |
| Treatment goal | Prevent progression to active disease | Cure and stop transmission |
| Typical regimen | Shorter (e.g., isoniazid ± rifapentine/rifampin for 3–9 months) | RIPE multi-drug therapy for months; DOT commonly used |
The Key Insight
A positive skin test or IGRA proves infection, not disease. The symptomatic, contagious patient with an abnormal chest film and positive sputum has active TB and needs airborne isolation; the well patient with only a positive test and a clean X-ray has latent infection, isn’t infectious, and is treated to keep it that way. Risk of reactivation rises with immunosuppression — HIV, TNF-inhibitors, transplant, and advanced age — which is why latent TB gets treated rather than just watched.
NCLEX Pearls
- ✦Latent TB: positive test, normal X-ray, no symptoms, NOT infectious, no isolation. Active TB: symptomatic, abnormal X-ray, positive sputum, airborne precautions.
- ✦A positive PPD means infection — confirm activity with chest X-ray and sputum before deciding on isolation.
- ✦Treating latent TB prevents progression — especially important before starting immunosuppressants.
- ✦Active disease needs multi-drug therapy for months; latent uses shorter, fewer-drug regimens.
Related Resources
Standards & sources
Fact-checked Jun 21, 2026This page is written to align with CDC / HICPAC · Infectious Diseases Society of America (IDSA) / SHEA. It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →