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CONCEPT OF DISEASE. COMMUNITY RESEARCH PROGRAM 1 FAJAR AWALIA YULIANTO. The modern Epidemiology : “Using quantitative methods to study , prevent, and control the disease in human population”. CAUSATION OF DISEASE. GENETIC FACTOR GOOD HEALTH POOR HEALTH
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CONCEPT OF DISEASE COMMUNITY RESEARCH PROGRAM 1 FAJAR AWALIA YULIANTO
The modern Epidemiology : “Using quantitative methods to study , prevent, and control the disease in human population”
CAUSATION OF DISEASE GENETIC FACTOR GOOD HEALTH POOR HEALTH ENVIRONMENTAL FACTORS (INCLUDING BEHAVIOURS)
EVALUATING INTERVENTIONS TREATMENT MEDICAL CARE GOOD HEALTH ILL HEALTH HEALTH PROMOTION PREFENTIVE MEASURES PUBLIC HEALTH SERVICES
DEFINITION • HEALTH • Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity • DISEASE • Conformed in epidemiology, as simple as “disease present” and “disease absent”
NATURAL HISTORY OF DISEASE Death Good health Sub-clinical changes Clinical changes Recovery
THE CONCEPT OF CAUSE • A cause of a disease or injury is an event, condition, characteristic or a combination of these factors which plays an important role in producing the health outcome
IS THE CAUSE SUFFICIENT OR NECESSARY FORMING THE DISEASE? • Sufficient if: • It inevitably produces or initiates an outcome • Necessary if: • An outcome can not develop in its absence EACH SUFFICIENT CAUSE HAS A NECESSARY CAUSE AS A COMPONENT
FACTORS IN CAUSATION • Predisposing factors : age, sex, genetic traits and previous illness may create susceptibility • Enabling (Disabling) factors : low income, poor nutrition, bad housing and inadequate medical care may favor the development of illness • Precipitating factors : exposure to a specific disease agent or noxious agent may be associated with the onset of disease • Reinforcing factors : repeated exposure, unduly hard work may aggravate an established disease or injury
AGENT • as an element or substance, animate or in animate,the presence (or absence) of it may initiate or perpetuate a disease process.
COMPONENTS OF AGENT • Nutritional • Chemical • Physical • Infectious
HOST • A person or other living animal, that affords subsistence or lodgment to an infectious agent under natural condition.
COMPONENTS OF HOST • The age • Sex • Genetic-Hereditary • Ethnic / race • Physiologic / Psychological status • Habit / tingkah laku • Immunologic status • The previous illnes
ENVIRONMENT • As the aggregate of all the external conditions and influence affecting the life and development of an organisme.
COMPONENTS OF ENVIRONMENT • Physical environment : such as Geographic,Geology, Climate • Biological environment : such as people, flora, fauna ; population density, food • Socioeconomic, such as : income, education, culture, urbanization, economic growth, poverty, fertility etc.
CONSIDERATIONS FOR CAUSATION • Temporal relation: • Does the cause precede the effect? (essential) • Plausibility • Is the association consistent with the other knowledge? (MOA, evidence from experimental animal) • Consistency • Have similar results been show in other study? • Strength • What is the strength of the association between the cause and the effect? (relative risk) • Dose-response relationship • Is increased exposure to the possible cause associated with increased effect? • Reversibility • Does the removal of a possible cause lead to reduction of disease risk? • Study design • Is the evidence based in a strong study design? • Judging the evidence • How many lines of evidence lead to the conclusion?
THE INCUBATION PERIOD • The time interval between contact with an agent and the first clinical evidence of resulting disease . It depends on : • Portal of entry ( there is a defense mechanism) • The ability of multiplication (infectivity). • Number of agents • Level of antibody in the host It varies individually
Type of incubation period in the disease outbreak B A A : skewed to the left, when the disease has a short incubation period B : skewed to the right, when the disease has a longer incubation period
DEFENSE MECHANISM • THE ABILITY TO REACT AGAINST AGENT INVASION IN THE BODY : Consist of : • The external defense mechanism such asphysical and chemical reaction. • The internal defense mechanism : cellular andhumoral immunity
INTERLUDE The lightwave travel not in straight singular waveform. The further, the more curvature it formed.
TYPES OF DISEASES • Communicable diseases • Chronic non communicable diseases
COMMUNICABLE DISEASES The leading communicable diseases in the world are: • Acute respiratory infections (3,76 millions) • HIV/AIDS (2,8 millions) • Diarrhoeal diseases (1,7 millions) • Tuberculosis (1,6 millions) • Malaria (1 million) • Measles (0,8 million)
COMMUNICABLE DISEASES 1. Directly, from other infected humans or animals 2. Indirectly, through vectors, airborne particles or vehicles
COMMUNICABLE DISEASES • Vectors: insects or animals that carry infectious agents from person to person • Vehicles: contaminated objects or elements of the environment • Contagious: ability to spread between humans without intervening vector or vehicle
COMMUNICABLE DISEASES • Epidemics: the occurence of cases in excess of what is normally expected in a community or region • Endemic: the relatively stable pattern of occurence in a given geographical area or population group at relatively high prevalence and incidence
COMMUNICABLE DISEASESCHAIN OF INFECTION • The Infectious agent • The transmission process • The host • The environment
COMMUNICABLE DISEASESTHE INFECTIOUS AGENT The factors determining the nature of the infection: • Pathogenicity: The ability to produce a disease. Measured by ratio number of persons whom clinically ill compared to the exposed • Virulence: The severity of disease • Infective dose: The amount required to cause infection in susceptible subjects • Reservoir: The natural habitat • Source of infection:The person or object from wich the host acqures the agent
COMMUNICABLE DISEASESTHE TRANSMISSION PROCESS • Direct transmission • Indirect transmission
COMMUNICABLE DISEASESTHE HOST • Extremely vary between individuals • Determined by self-reaction to the agents
COMMUNICABLE DISEASESENVIRONMENT • Plays a critical role in the development of communicable diseases
CHRONIC NON COMMUNICABLE DISEASES The leading chronic diseases in the world are: • CVD (17,5 million deaths) • Cancer (7,5 million deaths) • Chronic respiratory disease (4 million deaths) • Diabetes (1,1 million deaths)
CHRONIC NON COMMUNICABLE DISEASES The underlying determinants of health and their impact on chronic diseases Common Modifiable & non modifiable risk factors Intermediate Risk factors Main chronic diseases Socioeconomics, Cultural, political & Environmental factors
CHRONIC NON COMMUNICABLE DISEASES Levels of prevention: • Primordial prevention • Primary prevention • Secondary prevention • Tertiary prevention
REFERENSI • Bonita, R., Beaglehole, R., Kjellstrom, T. Basic epidemiology, 2nd ed. Geneva, World Health Organization, 2006