What this test measures
Anti-DNase B (ADB or DNB) measures antibodies your immune system makes against deoxyribonuclease B, an enzyme produced by Group A streptococcus (Streptococcus pyogenes). Like ASO (anti-streptolysin O), it confirms that you have had a recent streptococcal infection — but anti-DNase B rises later (peaks at 6–8 weeks vs 3–5 weeks for ASO) and stays elevated longer, making it useful when ASO is already declining or when the original infection was on skin rather than the throat.
The test is a quantitative immunoassay reported in IU/mL. It is usually ordered together with ASO; the combination raises sensitivity for recent strep infection to over 90%.
Why it matters
Rheumatic heart disease (RHD) remains a major problem in India, with prevalence still 1–2 per 1000 children in some regions despite progress. ICMR's rheumatic heart registry has documented thousands of cases of post-streptococcal complications — acute rheumatic fever (ARF), Sydenham chorea, and post-streptococcal glomerulonephritis (PSGN) — most occurring weeks after a sore throat or skin infection that may not have been treated.
Anti-DNase B is essential in this workup because the strep infection has often resolved by the time the rheumatic complication appears. ASO is the first-line test, but anti-DNase B picks up cases that ASO misses (especially skin/pyoderma-related PSGN — common in Indian children with impetigo) and remains positive for longer, allowing late diagnosis. Together they support the Jones criteria for ARF diagnosis. A positive result does not require antibiotic treatment of the original infection (it has cleared) but does prompt long-term penicillin prophylaxis if rheumatic carditis or chorea is confirmed.
How to prepare
No fasting required. Continue normal medications. Mention recent antibiotic use (which may not affect the antibody level) and any sore throat or skin infection in the preceding 2–3 months.
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| Anti-DNase B (IU/mL)[1][2][3] | Children: < 240 IU/mL · Adults: < 120 IU/mL (assay-dependent) | Low or normal level makes recent streptococcal infection less likely. In suspected rheumatic fever, low levels of both ASO and anti-DNase B make a strep-related cause unlikely. | Elevated level confirms a recent (within 2–4 months) streptococcal infection. Rising titres over 2–3 weeks are more meaningful than a single high value. Supports diagnosis of acute rheumatic fever (per modified Jones criteria), Sydenham chorea, or post-streptococcal glomerulonephritis. |
ASO vs Anti-DNase B — when each is positive
| Feature | ASO | Anti-DNase B |
|---|---|---|
| Peaks after infection | 3–5 weeks | 6–8 weeks |
| Stays elevated | ~2–3 months | ~3–6 months |
| Throat-strep infection | ~80% positive | ~80% positive |
| Skin / pyoderma infection | Less reliable | More reliable |
| Combined sensitivity | ~80% | ~80% |
| ASO + DNase B combined | ~95% | ~95% |
Frequently asked questions
Do I need to fast?
No fasting required.
Why do I need both ASO and anti-DNase B?
They peak at different times after infection. Together they catch about 95% of recent strep infections; alone, each catches only ~80%.
My child had a sore throat — should we test?
Acute sore throat is diagnosed by throat swab, not ASO/DNase B. These antibody tests are used 2–8 weeks later when there are signs of rheumatic fever, glomerulonephritis or chorea.
How long does a positive result stay positive?
Anti-DNase B can stay elevated for 3–6 months after a strep infection. Serial testing (2–3 weeks apart) showing a rising titre is more informative than a single value.
My anti-DNase B is high — does my child need antibiotics?
A high level alone does not require treating the past infection. However, if rheumatic carditis or chorea is diagnosed, long-term penicillin prophylaxis (often for many years) is needed to prevent recurrence and progressive heart valve damage.
Can the test be falsely positive?
Other infections rarely raise anti-DNase B. False elevation is uncommon. Interpret in clinical context.
How long is the report?
Typically 1–2 days.
Related Autoimmune / Rheumatology tests
Tests commonly ordered alongside ANTIDNASE-B (DNB), or that help interpret an unexpected result.
Sources & references
- NIH MedlinePlus — Anti-DNase B Test · accessed 2026-05-30T00:00:00.000Z
- NCBI StatPearls — Acute Rheumatic Fever · accessed 2026-05-30T00:00:00.000Z
- WHO — Rheumatic Heart Disease · accessed 2026-05-30T00:00:00.000Z
- ICMR — Rheumatic Heart Disease Program · accessed 2026-05-30T00:00:00.000Z
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