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Acute rheumatic fever
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Acute rheumatic fever is not an infection of the heart: it is an immune complication of a different infection, group A streptococcal pharyngitis, a throat infection. It is called nonsuppurative because the bacteria do not actually form pus where the damage appears.
The mechanism has a name: molecular mimicry. While fighting the streptococcus, the immune system reacts the wrong way because some parts of the bacterium, the M protein and a molecule called N-acetyl-beta-D-glucosamine, structurally resemble myosin, a protein of the body's own muscle. The immune system learned one face and strikes anyone who resembles it. That is where cardiac myositis, inflammation of the heart muscle, and valvulitis, inflammation of the heart valves, come from.
There is a characteristic delay: the response appears two to four weeks after the infection. It is seen mainly in children aged 5 to 15, and a major long-term consequence is rheumatic heart disease, the damage left behind in the valves.
In brief
Acute rheumatic fever is a nonsuppurative immune complication of group A streptococcal pharyngitis.
It is triggered by molecular mimicry between streptococcal antigens and self antigens: M protein and N-acetyl-beta-D-glucosamine resemble myosin, hence the cardiac myositis and valvulitis.
The immune system learned one face and strikes anyone who resembles it.
It usually appears two to four weeks later, mostly in children aged 5 to 15; a major long-term consequence is rheumatic heart disease.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingAcute Rheumatic Fever, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
Updated