Rheumatic fever--is it still a problem?
The incidence of rheumatic fever has declined in industrialized countries since the 1950s and now has an annual incidence of around 0.5 cases per 100,000 children of school age. In developing countries it remains an endemic disease with annual incidences ranging from 100 to 200 per 100,000 school-aged children and is a major cause of cardiovascular mortality. Interest in the pathogenesis of rheumatic fever was rekindled by outbreaks in the USA (1985-1987) and the rare cases still seen in industrialized countries. The current concept is that the disease results from the host's poorly adapted autoimmune response to group A beta-haemolytic streptococci. The risk of developing rheumatic fever following untreated tonsillopharyngitis is 1% in the civilian population. Knowledge of virulence factors has been greatly enriched by progress in molecular biology. One of the key elements is protein M, a surface protein on the bacterial wall which carries specific epitopes. Several serotypes which lead to rheumatic fever have been recognized among more than 80 identified serotypes. However, the reason why specific strains within a given serotype have increased rheumatogenic virulence remains unknown. The causal strain adheres to the oral and pharyngeal cells and then releases its degradation products. These products present antigenic determinants which cross-react with certain human tissues, particularly in cardiac valve tissue and myocardium. Diagnosis is now difficult owing to the low incidence. Late diagnosis can have serious consequences and acute rheumatic fever is a therapeutic emergency requiring immediate antibiotic and anti-inflammatory treatment. In most of Europe there is tacit agreement that all cases of pharyngitis and tonsillitis should be treated with antibiotics without identification of the causal agent despite the fact that only about 20% of the cases are caused by group A beta-haemolytic streptococci, and could lead to rheumatic fever.
Olivier
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Service de Pediatrie Generale, Hôpital Louis Mourier, Colombes, France.
D019049:Developed Countries; D020022:Genetic Predisposition to Disease; D006801:Humans; D015994:Incidence; D010612:Pharyngitis / Q000453:epidemiology / Q000382:microbiology; D012213:Rheumatic Fever / Q000453:epidemiology* / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000472:pathogenicity