Is strep throat a result of the harmful cross-reaction of bacteria and antibody (pg 13) and is there then a link to heart murmur?
People with a Streptococcus infection like strep throat make antibodies to the bacteria. A very small proportion of people make enough of an antibody that also binds to a protein associated with heart valves (this is called cross-reaction.) Then the immune system, thinking the heart is a bacterium, attacks it. This can lead to valve damage. Many older people with heart murmurs had rheumatic fever (as this cross-reaction following a Strep infection is called) as children. It is rare now because we treat so early with antibiotics that people make only a little antibody; but it is still common in the developing world.
