is a delayed, immune-mediated complication of group A streptococcal pharyngitis, and it appears two to four weeks after the sore throat has resolved. It is diagnosed clinically, using the Jones criteria as revised by the American Heart Association in 2015. No single test confirms or excludes it, and the criteria only work alongside evidence that a streptococcal infection has actually occurred.
The 2015 revision made two changes of practical importance: it separated low-risk from moderate- to high-risk populations, and it accepted subclinical carditis — valvular regurgitation seen on echocardiography without an audible murmur — as a major criterion.
The diagnostic rule
The diagnosis requires evidence of preceding group A streptococcal infection together with either:
- two major manifestations, or
- one major plus two minor manifestations.
Major manifestations are the five characteristic findings of the disease: carditis, arthritis, chorea (involuntary, purposeless movements), erythema marginatum (a ring-shaped rash) and subcutaneous nodules. Minor manifestations are less specific findings: joint pain, fever, raised inflammatory markers and a prolonged PR interval.
What counts as a major or minor manifestation depends on the population the child comes from, because the same finding carries different weight where the disease is common and where it is rare. The 2015 criteria define a low-risk population as one with an incidence of 2 or fewer cases per 100,000 school-aged children per year, or a rheumatic heart disease prevalence of 1 or less per 1,000 population per year.
Major manifestations
| Manifestation | Low-risk populations | Moderate- and high-risk populations |
|---|---|---|
| Carditis | Clinical or subclinical | Clinical or subclinical |
| Arthritis | Polyarthritis only | Monoarthritis, polyarthritis or polyarthralgia |
| Chorea | Yes | Yes |
| Erythema marginatum | Yes | Yes |
| Subcutaneous nodules | Yes | Yes |
Monoarthritis (one inflamed joint) and polyarthralgia (pain in several joints) without objective joint signs count as major manifestations only in moderate- to high-risk populations. In low-risk populations, joint pain without inflammation is a minor manifestation.
Minor manifestations
The inflammatory markers are the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). The PR interval is the interval on the electrocardiogram between atrial and ventricular activation, and its prolongation is first-degree atrioventricular block.
| Manifestation | Low-risk populations | Moderate- and high-risk populations |
|---|---|---|
| Joint pain | Polyarthralgia | Monoarthralgia |
| Fever | 38.5 °C or higher | 38 °C or higher |
| Inflammatory markers | ESR 60 mm/hour or CRP 3.0 mg/dL or more | ESR 30 mm/hour or CRP 3.0 mg/dL or more |
| Prolonged PR interval | Yes, age-adjusted, unless carditis is counted as major | Same |
Evidence of preceding streptococcal infection
The criteria are necessary but not sufficient: the child must also have evidence of a recent group A streptococcal infection. It can come from any one of the following, and because the rheumatic manifestations appear weeks after the sore throat, the direct tests for the bacterium are often already negative.
- Raised or rising antistreptolysin O () or — antibodies against two products the streptococcus releases — interpreted against age-specific upper limits.
- Positive throat culture or rapid antigen test — often negative by the time the rheumatic manifestations appear, particularly if antibiotics were given early.
- Recent scarlet fever, which serves as clinical evidence of the infection.
How to interpret the ASO titre
The ASO titre is an antibody response to streptolysin O, and it is widely over-read. Several limits apply:
- It reflects past exposure to group A Streptococcus, not current infection. Children of 6-9 years, the age of peak exposure, commonly have raised titres from remote infections.
- It peaks about 3-6 weeks after infection and stays elevated for weeks to months, so a single high value cannot be dated.
- It is not universally positive in rheumatic fever: ASO is elevated in roughly 85% of patients with the disease, which means a normal value does not exclude it. Testing anti-DNase B as well increases the yield, because a proportion of patients who are negative for one antibody are positive for the other.
- Titre does not correlate with disease severity.
- The most informative approach is serial testing: a significant rise between a sample taken at presentation and one taken 2-3 weeks later indicates recent infection, whereas a stable titre suggests a remote one. Age-related reference values differ, so the same numerical value that is unremarkable in a 15-year-old may be raised in a 7-year-old.
The criteria identify the disease; they do not, on their own, tell you how much the heart is involved. The extent of carditis during the episode, and the risk of a further attack in the years afterwards, are what decide how the valves look a decade later.