Preventive medicine

Overview
Generally speaking, preventive medicine is the part of medicine engaged with preventing disease rather than curing it. It can be contrasted not only with curative medicine, but also with public health methods (which work at the level of population health rather than individual health).

Professionals involved in the public health aspect of this practice may be involved in entomology, pest control, and public health inspections. Public health inspections can include recreational waters, pools, beaches, food preparation and serving, and industrial hygiene inspections and surveys.

As a medical specialty
In the United States, preventive medicine is a medical specialty, one of the 24 recognized by the American Board of Medical Specialties (ABMS). It encompasses three areas of specialization:
 * General preventive medicine and public health
 * Aerospace medicine
 * Occupational medicine

In order to become board-certified in one of the preventive medicine areas of specialization, a licensed U.S. physician (M.D. or D.O.) must successfully complete a preventive medicine medical residency program following a one year internship. Following that, the physician must complete a year of practice in that special area and pass the preventive medicine board examination. The residency program is at least two years in length, and includes completion of a post-graduate masters degree in public health (MPH) or equivalent. The board exam takes an entire day: The morning session concentrates on general preventive medicine questions. The afternoon session concentrates on the one of the three areas of specialization that the applicant has studied.

In addition, there are two subspecialty areas of certification:
 * Medical toxicology (MT)
 * Undersea and hyperbaric medicine (UHB), formerly "undersea medicine"

These certifications require sitting for an examination following successful completion of an MT or UHB fellowship and prior board certification in one of the 24 ABMS-recognized specialties

Rose's theorem
Rose's Theorem states that "a large number of people at small risk may give rise to more cases of disease than a small number who are at high risk."