High rates of impetigo are a marker for widespread streptococcal transmission. Diagnosis
Chorea is distinctive, if the health care provider is familiar with it. The diagnosis is then made by the typical acute onset in the weeks following a sore throat or other minor infection, plus evidence of inflammation (raised CRP and/or ESR) and evidence of recent streptococcal infection. To confirm recent streptococcal infection:

Throat culture
Anti-DNAse B titre (peaks at 8–12 weeks after infection)
Anti-streptolysin O titre (peaks at 3–5 weeks)None of these tests are 100% reliable, particularly when the infection was some months previously. Further testing is directed more towards alternative diagnoses and other manifestations of rheumatic fever:

Echocardiography
EEG
Lumbar puncture
Magnetic resonance imaging or computed tomography scan of the brain (alterations in caudate nucleus and putaminal enlargement have been described in some patients)

Management
Management of Sydenhams chorea is based on the following principles:

Eliminate the streptococcus – it may not be of any use for the index patient but further spread of that specific clone will be prevented. Treat the movement disorder
Immunosuppression
Prevention of relapses and further cardiac damage
Manage the disabilityThere is a UFMG rating scale for Sydenhams chorea, from Brazilian Universidade Federal de Minas Gerais (UFMG), for research purposes, but it only looks at motor function not psychiatric/behavioural symptoms. Occupational therapy and physiotherapy is useful for maintaining function and muscle tone. Treatment with sodium valproate is effective for controlling symptoms, but it doesn’t speed up recovery. Haloperidol was used previously, but caused serious side effects e.g. tardive dyskinesia.
Case reports exist to support carbamazepine and levetiracetam; other drugs tried include pimozide, clonidine, and phenobarbitone. Immunosuppression
Immunosuppression is used inconsistently in Sydenhams chorea. The model of an autoimmune disorder would support its use. One randomized controlled trial of steroids from Paz, Brazil in 2006 (22 cases) showed remission reduced to 54 days from 119 days. Various other reports of use of oral or IV steroids from Israel, Italy and Brazil . Immunoglobulin has been used in Holland and South Africa. Some improvement can be seen within a few days of IV steroids. In Italy, prednisolone reduced average duration of symptoms from 9 weeks to 4 weeks, and these were severe cases. South African group found less neuropsychiatric complications at 6 months with IVIG treatment (IVIG preferred due to fear of TB reactivation).A course of penicillin is usually given at diagnosis to definitively clear any remaining streptococci, but there is no evidence that this is an effective treatment. Active infection is usually cleared by diagnosis. Penicillin prophylaxis, on the other hand, is essential to treat cardiac features of rheumatic fever, even if subclinical (American Heart Association guideline). If the case is of isolated chorea, it is arguable whether cardiac risk justifies prophylaxis or not, however it is likely to reduce recurrence. There are several historical case series reporting successful treatment of Sydenhams chorea by inducing fever. Prognosis
Motor problems including chorea settle within an average of 2–3 months. Recurrence seen in 16–40% of cases. Recurrence is more likely with poor compliance with penicillin prophylaxis.