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WordNet
subacute bacterial endocarditis

n. a chronic bacterial infection of the endocardium and heart valves; symptoms develop slowly

Wikipedia
Subacute bacterial endocarditis

Subacute bacterial endocarditis (also called endocarditis lenta) is a type of endocarditis (more specifically, infective endocarditis). Subacute bacterial endocarditis can be considered a form of type III hypersensitivity.