Pub Health

• Public Health


  The science and art of preventing disease, prolonging life, and promoting physical and mental health and efficiency
• Organized Community Effort for

  • Sanitation of the environment
  • Control of community infections
  • Education of the individual in principles of personal hygiene
  • Organization of medical service for the early diagnosis and treatment of diseases
  • Development of a social machinery which will ensure a standard of living adequate for the maintenance of health
• Agencies set to carry out organized community health activities

  • Voluntary (private, supported wholly or in large part by non-tax funds e.g., NGOs, private clinics, private foundations)
  • Governmental (public, official or tax supported e.g., government hospitals, health centers, district hospitals)
• WHO definition of Health

  A state of complete physical, mental, and social well-being, not merely the absence of disease and infirmity
• Dimensions of Health


  • Physical
  • Mental
  • Emotional
  • Social
  • Spiritual
  • Sexual
• Disease

  A diagnostic category which classifies a particular illness, symptoms, or pathological components of the illness
• Illness

  A highly personal stage wherein the person feels unwell, person's experience of his disease
• Normal Health

  A state of well-being in which the individual is free from disabling effect and has sufficient vigor to carry on the usual requirements of life, with social adaptation that produces self-gratification and enjoyment
• Holistic Health

  Views a person being whose psycho-social-cultural-spiritual-relationships with the environment directly affect health
• Determinants of Health and Disease

  • Genes
  • Nutrition
  • Population problem
  • Person's lifestyle
  • Iatrogenic disease
• Malnutrition

  • Failure to ingest food (poverty)
  • Failure to utilize food (PKU, celiac disease, pernicious anemia)
  • Increase food requirements (childhood, adolescence, pregnancy, sickness)
• Agent

  Any element, substance, or force whether living or non-living, the presence or absence of which can perpetuate a disease
• Types of Agents

  • Living (plant and animals - bacteria, fungi, molds, yeast, arthropods, helminths, protozoan)
  • Non-living (Physical and Mechanical agents - extremes in temperature, light, electrocution, physical trauma; Chemical agents - exogenous, endogenous)
  • Nutrient (deficiency or excess is bad)
• Host

  A vertebrate or invertebrate capable of getting infected by and exposed to the agent
• Host Factors of Disease


  • Genetic make up
  • Age
  • Sex
  • Race
  • Habits, customs, and tradition
  • Exposure to the agent
  • Defense mechanism of the host
  • State of nutrition
• Categories of Environment

  • Physical (humidity, weather, topographic features)
  • Biologic (presence of living agent)
  • Socioeconomic (population density, priority is food not health, lack of awareness, presence of fast food, urbanization, political commitment)
• Disease results from an imbalance between a disease agent and man
• The nature and extent of the imbalance depends on the nature and characteristics of the host and the agent
• The characteristics of the host and the agent are influenced considerably by the conditions of the environment
• Epidemiologic Triangle


  A change in one of the components (host, agent, environment) causes change in the other
• Web of Causation


  Disease never depends on a single isolated cause but rather develops as a result of chains of causation
• Wheel


  Depicts the relationship of host with its genetic material and how it is influenced by the environment
• Natural History of Disease

  Comprises the body of both qualitative and quantitative knowledge of agent, host and environmental factors and its development from the first forces which initiate the process in the environment through the resulting changes that take place in man and continuing until equilibrium is reached, or defect, disability or death ensues
• Phases of the Natural History of Disease

  • Pre-pathogenesis (state of susceptibility)
  • Pathogenesis (stage of disability)
• Possible Results of Infection

  • Recovery
  • Balanced equilibrium
  • Subclinical conditions
  • Clinical case
• Requirements for Infection to Occur

  • Presence of agent
  • Suitable reservoir
  • Presence of susceptible host
  • Suitable portal of entry
  • Portal exit from the host
  • Appropriate means of dissemination
• Incubation Period


  Interval between the time of entry of agent into the host and the onset of signs and symptoms
• Clinical Horizon


  Clinical manifestation of disease which appear after the incubation period
• Types of Fever

  • Continuous (dengue)
  • Intermittent (malaria)
  • Remittent (typhoid)
• Portal of Entry


  A suitable portal of entry is requisite for a successful infection. The portal of entry may also be the portal of exit.
• Possible Portals of Entry

  • Respiratory tract
  • Mucous membranes
  • Skin and subcutaneous tissue
  • GIT
  • Conjunctiva
  • Placenta
  • GUT
• Period of Communicability


  The period at which the patient is very infectious
• Types of Carriers


  • Incubatory
  • Convalescence
  • Temporary
  • Chronic
• Characteristics of Agents Directly Related to the Host


  • Antigenicity
  • Toxicity
  • Invasiveness
  • Virulence
  • Pathogenicity
  • Infectivity
• Carriers

  • Incubatory
  • Convalescence
  • Temporary
  • Chronic
• Incubatory


  Having an elapsed time between first exposure to pathogen and first appearance of symptoms (measles)
• Convalescence


  Despite disappearance of symptoms, the patient still contains the organism (cholera, diphtheria)
• Temporary


  Patient is infectious only during the period of illness (influenza)
• Chronic


  Patient continuously sheds off the infectious for a long period of time (typhoid, HIV, HBV, TB)
• Characteristics of agents directly related to the host

  • Antigenicity
  • Toxicity
  • Invasiveness
  • Virulence
  • Pathogenicity
  • Infectivity