EPIDEMIOLOGY Derived from word “Epidemic” Epi ------------------ means --------- Among Demos -------------- means --------- People Logos --------------- means --------- Study “Study of distribution frequency & determinants of health related states in specified population” “It is the study of the causes and distribution of disease in human populations.” According to WHO “Epidemiology is the study of the distribution and determinants of health-related states or events (including disease), and the application of this study to the control of diseases and other health problems.” Determinants: Causes and other factors that influence the occurrence of disease and other health-related events Components of epidemiology: I. II. III. Disease frequency Distribution of disease Determinants of disease Difference b/w Epidemic & Pandemic: Epidemic “Unusual occurrence of disease in a population in excess of its expected frequency and if disease is not prevalent then presence of at least two cases of that disease at same place” Or Pandemic “If a disease spreads over a very large geographical area and affects a major portion of population of world, it is called pandemic” Or Example Chicken pox, Cholera Influenza pandemic in 1918 & 1957 Cholera pandemic in 1962 Pandemic refers to an epidemic that has spread over Epidemic refers to an increase, often sudden, in the several countries or continents, usually affecting a number of cases of a disease above what is normally large number of people. expected in that population in that area. Example Outbreak: It carries the same definition of epidemic, but is often used for a more limited geographic area Endemic: It refers to constant presence and/or usual prevalence of a disease or infectious agent in a population within a geographic area An epidemiological approach helps planners a. To focus on the main problems of a community rather than of individual patients & b. To identify measures for improving the health of the community as a whole Epidemiology can increase the general understanding about a disease and particularly how it is transmitted even when the cause is unknown. In epidemiology, the assumption is that diseases do not occur randomly, but follow predictable patterns that can be studied and expressed in terms of What, Who, Where, When, How, Why, and What next The goal of epidemiology is to identify subgroups of the population who are at a higher risk of disease than usual and who will benefit the most from disease specific interventions. Epidemiological information can be used to develop prevention strategies according to: a. Time (peaks at a particular season) b. Place (limited to specific geographic areas) c. Person (groups at risk) Epidemiology in emergencies: Epidemiology in emergencies goes beyond simply understanding how diseases are contracted and spread. Objectives of epidemiology in emergencies Identifying the priority health problems in the affected community Determining the extent of disease existing within a community Identifying the causes of disease and the risk factors Determining the priority health interventions Determining the extent of damage and the capacity of the local infrastructure Monitoring health trends of the community Evaluating the impact of health programs Epidemiological indicators: Indicators are measures that reflect State of a population in terms of health, socioeconomic status etc Process and outcome of existing services Indicators are useful for measuring and describing the effects of a disaster on a population and for providing baseline measurements. Later, these measurements will help determine the outcome of the relief response. Types of Indicators: Indicators may be defined from surveys or an existing health information system. They might be i. Quantitative or ii. Qualitative ii. Qualitative indicators: i. Quantitative indicators: These are easily calculated from numeric information such These indicators measure people’s attitudes and as the total number of people, the number of people knowledge and are more difficult to measure. These according to age and sex etc indicators might be critical in explaining unexpected values of quantitative indicators. Examples of quantitative indicators include: Examples of qualitative indicators include: Incidence: No. of cases or events that occur within a Awareness of the value of immunization: Low awareness defined e.g. incidence of measles among children may explain the high incidence of measles in a population living within five kilometres from a health Prevalence: Proportion of population with particular facility condition that is divided by total number of persons at risk Adherence to preventive interventions against for condition during that period HIV/AIDS: Poor compliance from youths in preventive e.g. prevalence of HIV/AIDS in a population. interventions (e.g.; A lack of understanding about“Be Faithful, Use a Condom” program) might explain the Morbidity rate: All persons in the population under increasing prevalence of HIV/AIDS in a population consideration e.g. belonging to a specific gender or age- Equity in distribution of resources: Inequitable group who become clinically ill during the specific period distribution of food might explain the increased mortality detected in a subgroup of a population Mortality rate: Number of deaths occurring in a Barriers to seeking treatment for malaria: Barriers to population in a specific period (usually a year) divided by seeking treatment such as unaffordable health services, the number of persons at risk of dying during that period might explain an increase in malaria-specific mortality e.g., mortality rate of infants during their first year of life DISEASE CONTROL It describes operation aimed at reducing Incidence of disease Duration of disease and consequently risk of transmission Effects of infection, including both physical and psychological complications Financial burden community Prevention “Action taken prior to the onset of disease, which removes possibility that a disease will ever occur” Intervention “Any attempt to intervene or interrupt usual sequence in the development of disease in man” Level of prevention: Methods of intervention: i. Primordial: Prevention in chronic diseases by i. Health promotion: Process to improve health changing in lifestyle e.g. DM, CHF through education, environmental modification, ii. Primary: Applied in pre pathogenesis phase: medical checkups and healthy life style iii. Secondary: Applied in pathogenesis phase: Halts ii. Specific protection: measures applicable to progress of disease: Tool for control of intercept cause of disease before involvement e.g. transmission immunization against diseases iv. Tertiary: Applied in late pathogenesis phase: All iii. Early diagnosis & prompt treatment measures to reduce impairments & sufferings iv. Disability limitation: Lack of ability to perform activity within range v. Rehabilitation: Combined coordinated use of medical, social, educational and vocational measures for training individuals to functional ability References Epidemiology and surveillance, Public health guide for emergencies, The Johns Hopkins and the International Federation of Red Cross and Red Crescent Societies, 220-283 http://www.who.int/topics/epidemiology/en/ (20-09-2017)