There are many factors that play a role in the origin of disease, such factors include water pollution, air pollution, food contamination and sanitation. Such factors can be controlled if the community takes preventive measures in ensuring clean water and sanitation, so at the individual level the disease will not occur and also there are many communicable disease which are transmitted transmitted from person to person so if the community is healthy there are less chances of communicable disease and therefore you can understand community health is essential for individual health.