Subacute

In medicine, describing a disease as acute denotes that it is of short and, as a corollary of that, of recent . The quantitation of how much time constitutes "short" and "recent" varies by disease and by context, but the core denotation of "acute" is always qualitatively in contrast with "chronic", which denotes long-lasting disease (for example, in acute leukemia and chronic leukemia). In addition, "acute" also often connotes two other meanings: onset and , such as in acute myocardial infarction (AMI), where suddenness and severity are both established aspects of the meaning. It thus often connotes that the condition is fulminant (as in the AMI example), but not always (as in acute rhinitis, which is usually synonymous with the common cold). The one thing that acute MI and acute rhinitis have in common is that they are not chronic. They can happen again (as in recurrent pneumonia, that is, multiple acute pneumonia episodes), but they are not the same ongoing for months or years (unlike chronic obstructive pulmonary disease, which is).

A noncount sense of "acute disease" refers to the acute phase, that is, a short course, of any disease entity. For example, in an article on ulcerative enteritis in poultry, the author says, "in acute disease there may be increased mortality without any obvious signs", referring to the acute form or phase of ulcerative enteritis.

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