Epidemiology meaning, scope & terminology

Epidemiology

1. INTRODUCTION TO EPIDEMIOLOGY PRESENTED BY: Jagan Kumar Ojha MSc. Tutor Dept. of Community Health Nursing SNC

2. MEANING OF EPIDEMIOLOGY Epidemiology is derived from Greek word “ E pidemic ” EPI – On / upon DEMOS – people LOGOS – study of Epidemiology means the study of disease in human population .

3. DEFINITION “The study of the distribution and determinants of health-related states or events in specified populations, and the application of this study for the prevention and control of health problems” . As defined by John M. Last (1988)

4. Definition…. Distribution …… Frequency refers not only to the no. of health events such as the no. of cases of meningitis or diabetes in a population but also to the relationship of that number to the size of the population. The resulting rate allows epidemiologists to compare disease occurrence across different populations. Pattern refers to the occurrence of health-related events by time, place, and person .

5. Definition…. Determinants Determinants , which are the causes and other factors that influence the occurrence of disease and other health-related events. Illness does not occur randomly in a population, but happens only when the right accumulation of risk factors or determinants exists in an individual.

6. Other Definitions… The epidemiology is that branch of medical science which deals with epidemics ( Parkin , 1873) Epidemiology is the study of any disease, as a mass phenomenon (Greenwood , 1934) It is the study of the disease frequency, distribution and determinants among man ( Mac Mohan - 1960 )

7. AIMS To describe and measure the magnitude of health and disease problems in human populations. To identify etiological factors in the pathogenesis of disease. To provide the data essential to the planning, implementation and evaluation of services for the prevention and control of disease and to the setting up of priorities among those services.

8. Objectives To identify the etiology or cause of disease To determine the extent of disease To study the progression of disease To evaluate preventive and therapeutic measures for a disease or condition To develop public health policy

9. HISTORY OF EPIDEMIOLOGY

10. JOHN SNOW - father of epidemiology Snow conducted studies in 1854 when an epidemic of cholera erupted in the Golden Square of London. He began his investigation by determining where in this area persons with cholera lived and worked. He marked each residence on a map of the area, as shown in Figure. Snow believed that water was a source of infection for cholera, he marked the location of water pumps on his spot map, then looked for a relationship between the distribution of households with cases of cholera and the location of pumps. He noticed that more case households clustered around Pump A

11. JOHN SNOW However, that no cases of cholera had occurred in a two-block area just to the east of the broad street pump. Upon investigating, Snow found a brewery located there with a deep well on the premises. Brewery workers got their water from this well, and also received a daily portion of liquor . Access to these uncontaminated rations could explain why none of the brewery’s employees contracted cholera.

12. HIPPOCRATES “ENVIR O NMEN T A L INFLUENCES” On essay entitled “On Airs, Waters, and Places,” Hippocrates suggested that environmental and host factors such as behaviors might influence the development of disease.

13. FLORENCE NIGHTINGALE

14. Hence it refers to the progression of a disease process in an individual over time, in the absence of treatment. For example, untreated infection with HIV causes a spectrum of clinical problems beginning at the time of seroconversion (primary HIV) and terminating with AIDS and usually death. Natural History of Disease

15. The uses of epidemiology are : To study the health history of population and their disease trends. To arrive at community Diagnosis. To plan and evaluate health services. To estimate individuals risk and chance. To define and redefine syndromes. To complete the natural history of disease. To search for causes of health and disease by employing epidemiological methods. USES OF EPIDEMIOLOGY :

16. TERMINOLOGIES USED IN EPIDEMIOLOGY

17. INFE C TION: The entry and development or multiplication of an infectious agent in the body of man or animal.

18. EPIDEMIC An  epidemic   is the rapid spread of infectious disease to a large number of people in a given population within a short period of time.

19. EN D EMIC The constant p r es e nce o f a dise a se or wi t hin a infectious geographical a g ent area or population given gr o up, without importation f r om o u t s id e . E g . Common cold.

20. P AN D EMIC An which from epidem i c sprea d s count r y to country or over the whole world. Eg. AIDS

21. SPORA D IC Diseases that are seen only occasionally, and usually without geographic concentration, are called  sporadic  diseases.  Examples…   Tetanus , rabies, and plague .

22. ZOONOS I S Dise a ses or i n fect i o n s which are transmitted from vertebrate animal to human E.g . Rabies, plague

23. RESERVOIR The habit a t ( place f o r li v i n g ) where an infectious livin g , gr o ws agent and multiplies.

24. Disease carrier could refer to: Asymptomatic carrier, a person or organism infected with an infectious disease agent, but displays no symptoms. CA R RIER

25. ISOL A TION A separat i on person infectious of a with d i sea s e con t a c t human wi t h bei n gs from o t her for the peri o d of co mm u n icabili t y .

26. INCUBATION PERIOD This is the time interval between the entry of the disease agent into the body and the appearance of first sign and symptom of the disease.

27. PATHOGENICITY c a u s e Ability to the disease.

28. CON T AGIOUS t h at is t h r o u g h A disease transmitted direct contact . Eg. STD , flu.. etc

29. VIRUL E NCE Measure the severity of disease.

30. FOMITES I n ani m ate articl e s t h a n f o od or c o n t a m i n ated other wat e r by the infectious di s cha r ge s . e.g. Clothes, utensil, furniture etc.

31. VEC T OR Usually an arthropod eg. Mosquito which tran s fers an infectious agent from an infected person to a healthy person . Ticks, mites, lice etc.

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