The United States Public Health Service (USPHS) is a division of the Department of Health and Human Services concerned with public health. It contains eight out of the department's eleven operating divisions. The assistant secretary for health (ASH) oversees the PHS. The Public Health Service Commissioned Corps (PHSCC) is the federal uniformed service of the USPHS, and is one of the eight uniformed services of the United States. Modern public health began developing in the 19th century, as a response to advances in science that led to the understanding of, the source and spread of disease. As the knowledge of contagious diseases increased, means to control them and prevent infection were soon developed. Once it became understood that these strategies would require community-wide participat