40-21 rule for duration of prophylaxis

Rheumatic fever is the cause of heart disease of poverty. It is caused by type II hypersensitivity reaction/ molecular mimicry where antibodies against group A beta hemolytic streptococci cross react with N acetyl glucosamine which is present in endothelium of heart valves, synovium, basal ganglia and skin.

Usual course of illness is 12 weeks and causes significant morbidity and mortality due to arthritis and carditis. With treatment course of illness is shortened to 1-2 weeks.

Primary prevention for rheumatic fever

Treat the sore throat with amoxicillin or penicillin within 9 days

Secondary prevention for rheumatic fever

Benzathine penicillin is given 3-4 weekly after test dose to prevent recurrent sore throats

Ideally in RF with valvular disease life long prophylaxis should be given as sore throats can occur any time. Recurrence will cause more antibody production and will cause accentuation of pre-existing damage. However due to practical issues the upper limit is set at 40 years. Penicillin must always be given after test dose. Due to risk of anaphylaxis adrenaline must be kept ready for use. Dose of adrenaline for anaphylaxis is 0.5 mg intramuscular 1:1000 dilution and can be repeated after 5-15 minutes.

The following data is a must know for NEETPG, INICET and FMGE exams in India.