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).

Les chaînes de transmission. Au mois de mai 2020, une épidémie d'encéphalite a éclaté dans l'Ain, à cause de… fromage de chèvre. En réalité, c'est toute une chaîne de transmission entre espèces animales qui s'est établie, jusqu'aux humains. En effet, comme le montre une enquête de Santé Publique France, l'encéphalite a été causée par des tiques, qui l'ont transmis à des troupeaux de chèvres du bassin d'Oyonnax. Le virus s'est ensuite propagé chez l'Homme par la production de fromage. Ces chaînes de transmission sont fréquentes chez les maladies qui touchent les humains (certaines grippes, potentiellement le nouveau coronavirus, etc.) et la compréhension des mécanismes de transmission inter-espèces est primordiale pour aider à développer de meilleurs traitements.

Systematic activities to prevent or cure health problems and promote good health in humans are undertaken by health care providers. Applications with regard to animal health are covered by the veterinary sciences. The term "healthy" is also widely used in the context of many types of non-living organizations and their impacts for the benefit of humans, such as in the sense of healthy communities, healthy cities or healthy environments. In addition to health care interventions and a person's surroundings, a number of other factors are known to influence the health status of individuals, including their background, lifestyle, and economic, social conditions and spirituality; these are referred to as "determinants of health." Studies have shown that high levels of stress can affect human health.[10]
Skip juice cleanses or liquid diets. A popular cleansing regimen for losing weight involves drinking only juice or another type of liquid for a few days to a week. This is dangerous because you could end up without essential nutrients. These extreme cleanses are also counterproductive because most people just gain back any weight they lost when they go back to eating normal food again. Doctors don't recommend any sort of diet like this, and say following a healthy diet and exercise routine is much better for losing weight.[15]