Cholera has been in the news recently, e.g., “Cholera Kills More than 1,500 People in Nigeria” (Guardian), “Haiti Races to Stem Cholera Epidemic” (BBC), and “724 Dead in Haiti's Cholera Outbreak” (CNN).
Browsing the Relative Index for “Cholera” yields two numbers:
The interdisciplinary number for cholera (362.196932, built with 362.19 Services to patients with specific conditions plus 6932 from 616.932 Cholera following instructions at 362.196–362.198 Specific conditions) is not given because it is rarely used. The focus of 362.1–362.4 Problems of and services to persons with illnesses and disabilities is on social provision of services to patients—social arrangements for providing hospitals, physicians, nurses, etc.—and most works on that topic cover all diseases or a broad range of diseases. The exceptions are diseases that cannot be cured quickly, as when it was necessary to establish tuberculosis sanatoriums. At 362.1–362.4 is a class-elsewhere note: “Class incidence of and public measures to prevent physical diseases in 614.4–614.5” and a see-Manual reference to 362.1–362.4 and 614.4–614.5 Problems of and services to persons with illnesses and disabilities and Incidence of and public measures to prevent disease. At 362.1 Physical illness is the see reference “For technology of medicine, see 610.”
Both numbers given in the Relative Index for cholera are subdivisions of 610 Medicine and health. The comprehensive number for cholera in medicine is 616.932 Cholera; it is the number with the Relative Index subentry “medicine.” An example of a work classed in 616.932 Cholera is Cholera; among the topics in its table of contents are transmission and epidemiology, virulence of Vibrio cholera, signs and symptoms, and treatment.
The other number for cholera—the number with the Relative Index subentry “incidence” —is 614.514 Cholera. Although “incidence” is a core concept of 614.514 Cholera, the scope of the number is actually broader, as an examination of the schedule reveals. The upward hierarchy includes 614.5 Incidence of and public measures to prevent specific diseases and kinds of diseases; hence public measures to prevent cholera are included in the scope of 614.514 Cholera. At 614.4 Incidence of and public measures to prevent disease are a class-here note and see reference:
Class here epidemiology
For incidence of and public measures to prevent specific diseases and kinds of diseases, see 614.5
Since both class-here notes and see references have hierarchical force, works that focus on epidemiology of cholera are classed in 614.514 Cholera. An example of a work classed in 614.514 Cholera is The Ghost Map: A Street, an Epidemic and the Two Men Who Battle to Save Victorian London; specifically, it is classed in 614.5140942109034 Incidence of and public measures to prevent cholera in 19th-century London (built with 614.514 Cholera plus T1—09 Historical and geographic treatment plus T2—421 Greater London, following instructions at T1—093–T1—099 Treatment by specific continents, countries, localities; extraterrestrial worlds, plus 09 Historical and geographic treatment in add table under T1—093–T1—099 plus 034 from T1—09034 19th century, 1800–1899, following instructions at 09 Historical and geographic treatment in add table under T1—093–T1—099). The Ghost Map deals with the discovery in nineteenth-century London that cholera was spread by unsanitary water. Its subject headings include:
Epidemics — England — London — History —19th century
A special subdivision of 614.4 treats history of epidemics—614.49 History of epidemics—but that is for epidemics in general; an example is Plagues & Poxes: The Impact of Human History on Epidemic Disease. Epidemics of a specific disease are classed in subdivisions of 614.5.
What if a classifier has a work limited to incidence of and public measure to prevent cholera, but goes first to 616.932 Cholera? In the upward hierarchy for 616.932 Cholera, at 616 Diseases, is the see reference: “For incidence of and public measures to prevent disease, see 614.4.”