L19 Rheumatic Fever

When strep throat is untreated, in [blank_start]1-3[blank_end]% of cases, it will develop into rheumatic fever. Acute rheumatic fever is a [blank_start]systemic[blank_end] disease, causing arthritis (in 60 - 80% of cases), carditis (in 30-45% of cases), and neurological symptoms (10% of cases). Essentially this means [blank_start]joints[blank_end] and [blank_start]cardiac[blank_end] tissue can become inflamed. Some patients will progress to chronic rheumatic [blank_start]heart disease[blank_end].

Risk factors for rheumatic fever include poverty and social disadvantage. This implies [blank_start]poor[blank_end] nutrition and [blank_start]overcrowding[blank_end]. The genetics and ethnicity of the [blank_start]host[blank_end] also influence risk. It is a [blank_start]polygenic[blank_end] disease so immune function genes, both innate and acquired matter. The bacterial genetics of the [blank_start]strain[blank_end] also change risk.

Acute rheumatic fever most commonly affects children 5-14 years of age.

Rheumatic heart disease most commonly affects adults aged 60-70 years.

Pathogenesis of ARF: 1. [blank_start]GAS[blank_end] throat infection 2. Activation of innate & acquired [blank_start]immune responses[blank_end] 3. Production of anti-GAS [blank_start]antibody[blank_end] that cross reacts with [blank_start]self[blank_end] tissues 4. Activation of [blank_start]cross-reactive T[blank_end] cells (eg myosin)

The pathology of ARF in joints is an immune [blank_start]complex[blank_end] formation (with antibody and [blank_start]synovial[blank_end] proteins), and an influx of inflammatory [blank_start]cells[blank_end]. It's commonly in [blank_start]large[blank_end] joints and affects [blank_start]multiple[blank_end] joints. This can occur simultaneously [blank_start]or[blank_end] can be ‘migratory’. It lasts for days/weeks, then resolves. It [blank_start]responds[blank_end] to anti- inflammatories.

Chorea is an abnormal involuntary movement disorder, and ARF can cause temporary chorea. In ARF chorea: 1. Antibody binds to proteins on a [blank_start]neuron[blank_end] – causing altered signalling and increased levels of [blank_start]dopamine[blank_end]. This causes involuntary [blank_start]movements[blank_end] that affects the trunk, limbs, face (grimaces, frowns). We only treat if [blank_start]necessary[blank_end], with anti- epileptic [blank_start]valproic[blank_end] acid or [blank_start]carbamazepine[blank_end]. ARF chorea develops [blank_start]weeks/months[blank_end] after GAS infection and is also referred to as Sydenham’s chorea or St. Vitus’s dance. It self resolves within [blank_start]1-6[blank_end] months.

An uncommon but diagnostic presentation of ARF are transient, small painless nodules on the trunk and bony areas which blanch on pressure

ARF carditis is caused by an antibody & [blank_start]T[blank_end] cell response against [blank_start]heart valve[blank_end] proteins and vascular cell adhesion molecule 1 ([blank_start]VCAM-1[blank_end]). Release of [blank_start]inflammatory[blank_end] mediators cause tissue damage and remodelling. It can be [blank_start]sever[blank_end] but conversely resolution can occur with therapy, with no [blank_start]lasting[blank_end] damage

10-25% of RHD patients will develop chronic RHD.

Which of these is not an indicator of severe RHD?

Treatment of ARF 1. Hospitalisation for [blank_start]investigations[blank_end] (Inflammatory markers, throat swab, anti-GAS serology, ECG, echocardiogram, chest x-ray) There is no [blank_start]urgency[blank_end] to begin treatment with ARF as there's no evidence to show it alters outcome of acute disease or heart damage. - To treat GAS - Oral [blank_start]penicillin[blank_end] V (250mg two or three times daily for [blank_start]10[blank_end] days) - To treat arthritis – [blank_start]paracetamol[blank_end] - To treat chorea, only if necessary – [blank_start]valproic acid and carbamazepine[blank_end] - To treat heart failure cardiac drugs may be necessary

Strategies to prevent ARF: • Increase [blank_start]awareness[blank_end] of rheumatic fever, what causes it and how to prevent it • Reduce household [blank_start]crowding[blank_end] • Improve [blank_start]access[blank_end] to timely and effective treatment for strep throat infections in [blank_start]priority[blank_end] communities