Indexing principles for Category C - Diseases
Category C contains MeSH terms for diseases. Category C trees are arranged in two ways: by the type of disease (INFECTION, NEOPLASM, ANIMAL DISEASES ) and by system (RESPIRATORY TRACT DISEASES, DIGESTIVE SYSTEM DISEASES, CARDIOVASCULAR DISEASES).
There is extensive coverage of diseases and many pre-coordinated disease terms are available. Many subheadings are available for Category C terms, and usually one or more will be applicable.
The MeSH definition of disease is very broad. In addition to the conditions generally recognized as disease, it also includes abnormalities, injuries, poisoning, addiction and pathological signs and symptoms.
Disease terms in MeSH exist at many levels of specificity. There are very general disease terms, such as LIVER DISEASES and METABOLIC DISEASES, as well as more specific disease terms, such as LIVER ABSCESS, AMEBIC and CALCIUM METABOLISM DISORDERS.
Always index a disease as specifically as possible. Indexers should check the MeSH vocabulary and tree information to make sure that a more specific term is not available. For example, an article about a patient with RAEB anemia, should be indexed not with the general term ANEMIA, but with the more specific term ANEMIA, REFRACTORY, WITH EXCESS OF BLASTS, which is treed under ANEMIA.