Acute rheumatic fever

What it is

Acute rheumatic fever is a post-infectious immune response to Group A Streptococcus (GAS), Streptococcus pyogenes. The etiology is a previous GAS pharyngitis or tonsillitis without antibiotic treatment. Molecular mimicry then turns antibodies against the body: an autoimmune attack on heart, joints, skin and CNS through a type II hypersensitivity reaction, which is where the inflammation and cell damage come from.

Peak incidence is 5-15 years of age. The latent period between the acute infection and the onset of rheumatic fever is given as 2-4 weeks in one source and as 2-6 weeks in another.

Causes and risk

Rheumatic fever is one of the non-suppurative complications of pharyngitis, alongside scarlet fever and post-streptococcal glomerulonephritis; the suppurative ones are peritonsillar abscess, retropharyngeal abscess, meningitis, otitis media and sinusitis.

That makes the treatment of the sore throat the point of attack. Antibiotic is indicated for: 1) a positive rapid test for group A streptococcus; 2) scarlet fever; 3) symptomatic pharyngitis whose sibling has documented streptococcal pharyngitis; 4) a past history of rheumatic fever; 5) a recent family history of rheumatic fever. The choice is Penicillin V for 10 days, or erythromycin if allergic to penicillin.

The other route through the same decision uses the Modified Centor criteria, counted one point each: 1) fever over 38 C; 2) absence of cough; 3) tender ant. cervical adenopathy; 4) tonsillar swelling or exudate; with age under 15 years adding one point and age over 45 taking one away. The score then decides: 1) a score above 1 calls for a rapid antigen detection test (RADT), and if it is positive give penicillin or amoxicillin first line, with cephalexin, clindamycin or azithromycin as alternatives for penicillin allergy; 2) a score of 4 or more is treated empirically.