Types. Economists Ronald G. Ehrenberg and Robert Smith, authors of Modern Labor Economics, identify two main types of labor unions: craft unions and industrial unions. Craft unions represent workers in a specific occupation.lthough union membership in the United States peaked in the mid-20th century and has declined since then, various types of labor unions remain an influential force in American business and politics.
U.S. Army Physicians Discovered the Cause of Yellow Fever. August 27, 1900. No one knew what caused the often-deadly yellow fever, but it occurred in epidemic proportions, with one person after another in a given area becoming sick. People feared the mysterious disease, until U.S. Army physician James Carroll endangered his own health in the name of science.
Typhoid fever facts. 1  Typhoid fever usually is caused by Salmonellae typhi bacteria. 2  Typhoid fever is contracted by the ingestion of contaminated food or water. 3  Diagnosis of typhoid fever is made when the Salmonella bacteria is detected with a stool culture.  Typhoid fever is treated with antibiotics.