The focus of public health interventions is to prevent and manage diseases, injuries and other health conditions through surveillance of cases and the promotion of healthy behavior, communities, and (in aspects relevant to human health) environments. Its aim is to prevent health problems from happening or re-occurring by implementing educational programs, developing policies, administering services and conducting research.[49] In many cases, treating a disease or controlling a pathogen can be vital to preventing it in others, such as during an outbreak. Vaccination programs and distribution of condoms to prevent the spread of communicable diseases are examples of common preventive public health measures, as are educational campaigns to promote vaccination and the use of condoms (including overcoming resistance to such).
The environment is often cited as an important factor influencing the health status of individuals. This includes characteristics of the natural environment, the built environment and the social environment. Factors such as clean water and air, adequate housing, and safe communities and roads all have been found to contribute to good health, especially to the health of infants and children.[13][24] Some studies have shown that a lack of neighborhood recreational spaces including natural environment leads to lower levels of personal satisfaction and higher levels of obesity, linked to lower overall health and well being.[25] It has been demonstrated that increased time spent in natural environments is associated with improved self-reported health [26], suggesting that the positive health benefits of natural space in urban neighborhoods should be taken into account in public policy and land use.
Personal health also depends partially on the social structure of a person's life. The maintenance of strong social relationships, volunteering, and other social activities have been linked to positive mental health and also increased longevity. One American study among seniors over age 70, found that frequent volunteering was associated with reduced risk of dying compared with older persons who did not volunteer, regardless of physical health status.[54] Another study from Singapore reported that volunteering retirees had significantly better cognitive performance scores, fewer depressive symptoms, and better mental well-being and life satisfaction than non-volunteering retirees.[55]
Good Health and Wellness in Indian Country is CDC’s largest single investment to ease health disparities that affect American Indians and Alaska Natives. Tribes and tribal organizations work on effective community-chosen and culturally adapted strategies to reduce commercial tobacco use and exposure, improve nutrition and physical activity, increase support for health literacy, and strengthen community-clinical links.
Public health also takes various actions to limit the health disparities between different areas of the country and, in some cases, the continent or world. One issue is the access of individuals and communities to health care in terms of financial, geographical or socio-cultural constraints.[50] Applications of the public health system include the areas of maternal and child health, health services administration, emergency response, and prevention and control of infectious and chronic diseases.
Personal health also depends partially on the social structure of a person's life. The maintenance of strong social relationships, volunteering, and other social activities have been linked to positive mental health and also increased longevity. One American study among seniors over age 70, found that frequent volunteering was associated with reduced risk of dying compared with older persons who did not volunteer, regardless of physical health status.[54] Another study from Singapore reported that volunteering retirees had significantly better cognitive performance scores, fewer depressive symptoms, and better mental well-being and life satisfaction than non-volunteering retirees.[55]
Since the late 1970s, the federal Healthy People Initiative has been a visible component of the United States’ approach to improving population health.[6][7] In each decade, a new version of Healthy People is issued,[8] featuring updated goals and identifying topic areas and quantifiable objectives for health improvement during the succeeding ten years, with assessment at that point of progress or lack thereof. Progress has been limited to many objectives, leading to concerns about the effectiveness of Healthy People in shaping outcomes in the context of a decentralized and uncoordinated US health system. Healthy People 2020 gives more prominence to health promotion and preventive approaches and adds a substantive focus on the importance of addressing social determinants of health. A new expanded digital interface facilitates use and dissemination rather than bulky printed books as produced in the past. The impact of these changes to Healthy People will be determined in the coming years.[9]
A la question "Pensez-vous que la pandémie globale actuelle a eu comme “effet positif” de souligner l'importance de l'épidémiosurveillance ?", le spécialiste nous répond par la positive. "Effectivement, elle met en lumière cet intérêt stratégique, et j'espère que les États mettront en place des dispositifs pour accroître cette dimension-là Mais finalement, quels vont être les leviers prioritaires pour renforcer l'épidémiosurveillance ? L'autre difficulté est que nous savons montrer a posteriori l'épidémiosurveillance mais, comme pour les séismes, nous avons encore du mal à concevoir des systèmes d'alerte efficace nous permettant d'anticiper suffisamment [les futures épidémies]. J'imagine qu'il y a une conscience aujourd'hui [de cette problématique] qui est plus forte qu'hier."
Le département de Santé Animale de l'Institut, dirigé par Muriel Vayssier-Taussat, étudie les interactions entre la santé animale et humaine. “Pour préserver la santé de l'Homme, une des voies est de préserver la santé animale” explique-t-elle. Mais cette protection ne doit pas être menée n'importe comment. Ces dernières années, il a été observé que la résistance aux antibiotiques avait largement augmenté chez de nombreux animaux dû à un usage massif. Ceci contribue à l'apparition de nouveaux virus plus résistants et donc potentiellement plus facilement transmissibles à l'Homme. L'unité Génétique Animale et Biologie Intégrative, dirigée par Claire Rogel-Gaillard, se consacre à l'étude de la diversité génomique en élevage, et son lien avec les santés : “Comment sélectionner des animaux qui vont être en bonne santé [...] tout en limitant l'usage d'anti-infectieux et en réduisant l'empreinte environnementale ? Il y a en fait un lien assez fort entre la durabilité des systèmes d'élevage et la santé des Hommes et animaux de la Terre.” A l'aide de travaux sur la variabilité individuelle des réponses immunitaires (aux maladies et aux vaccins) sur les animaux d'élevage, Mme Rogel-Gaillard explique qu'il “n'existe pas d'animal complètement optimal dans toutes les conditions et dans tous les environnements [...]. Une génétique optimale dans un environnement peut ne pas être optimale dans un autre.” 
Section 1331 of the Affordable Care Act gives states the option of creating a Basic Health Program (BHP), a health benefits coverage program for low-income residents who would otherwise be eligible to purchase coverage through the Health Insurance Marketplace. The Basic Health Program gives states the ability to provide more affordable coverage for these low-income residents and improve continuity of care for people whose income fluctuates above and below Medicaid and Children's Health Insurance Program (CHIP) levels.
Public health also takes various actions to limit the health disparities between different areas of the country and, in some cases, the continent or world. One issue is the access of individuals and communities to health care in terms of financial, geographical or socio-cultural constraints.[50] Applications of the public health system include the areas of maternal and child health, health services administration, emergency response, and prevention and control of infectious and chronic diseases.
Generally, the context in which an individual lives is of great importance for both his health status and quality of life. It is increasingly recognized that health is maintained and improved not only through the advancement and application of health science, but also through the efforts and intelligent lifestyle choices of the individual and society. According to the World Health Organization, the main determinants of health include the social and economic environment, the physical environment and the person's individual characteristics and behaviors.[13]

The premise of body cleansing is based on the Ancient Egyptian and Greek idea of autointoxication, in which foods consumed or in the humoral theory of health that the four humours themselves can putrefy and produce toxins that harm the body. Biochemistry and microbiology appeared to support the theory in the 19th century, but by the early twentieth century, detoxification based approaches quickly fell out of favour.[6][7] Despite abandonment by mainstream medicine, the idea has persisted in the popular imagination and amongst alternative medicine practitioners.[8][9][10] In recent years, notions of body cleansing have undergone something of a resurgence, along with many other alternative medical approaches. Nonetheless, mainstream medicine continues to view the field as unscientific and anachronistic.[9]
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