Rationale for secondary prophylaxis in rheumatic fever

Rationale for secondary prophylaxis in rheumatic fever

Rationale for secondary prophylaxis in rheumatic fever: In an epidemic of streptococcal infection, 3% develop rheumatic fever while in an endemic infection only 0.3% develop rheumatic fever. In an episode of rheumatic fever, 42% develop carditis while 58% do not. Of those with carditis, 66% develop residual rheumatic heart disease. This would mean that more a  quarter of those who develop rheumatic fever can end up with residual rheumatic heart disease.

In those without obvious carditis initially, up to 8% may manifest heart disease later. In individuals with a previous history of rheumatic fever, 60% develops a recurrence of rheumatic fever with a second streptococcal infection. Of those with a previous rheumatic carditis, 72% develops carditis during the recurrent episode while 29% do not. In those without carditis in the initial episode of rheumatic fever, only 7% develop carditis in the recurrent episode while 93% do not. The high recurrence rate of rheumatic fever and carditis with recurrent streptococcal infection is the basis for secondary prophylaxis of rheumatic fever with penicillin. 

Fortunately, group A beta hemolytic streptococci which cause rheumatic fever has not developed resistance to penicillin. Hence it is possible to prevent rheumatic fever by giving penicillin prophylaxis. Though ideal would be primordial and primary prophylaxis of rheumatic fever, more practical would be secondary prevention of rheumatic fever after an episode of rheumatic fever. Primordial prevention would involve large scale public health measures at the community level to prevent epidemics of streptococcal infection. Primary prevention is by treating each episode of streptococcal sore throat by a full course of penicillin. Here the stumbling block would be accurate detection of streptococcal sore throat as most cases of sore throat are likely to be viral in origin.