Epidemiological triad

EPIDEMIOLOGICAL TRIAD FOR II YEAR B.SC(N) COMMUNITY HEALTH NURSING I

1. EPIDEMIOLOGICAL TRIAD ENVIRONMENT AGENT HOST

2. AGENT The first link in the chain of disease transmission is a disease agent. The disease agent is defined as a substance, living or non living or a force, tangible or intangible, the excessive presence or relative lack of which may initiate or perpetuate a disease process. A disease may have a single agent, but more factors are responsible for disease transmission.

3. BIOLOGICAL AGENTS VIRUS BACTERIA PROTOZOVA FUNGUS CHARACTERISTICS: Infectivity Pathogenicity virulence

4. PHYSICAL AGENTS Exposure to excessive heat, cold, humidity, pressure, radiation, elecricity , sound etc..

5. CHEMICAL AGENTS ENDOGENOUS EXOGENOUS

6. MECHANICAL AGENTS

7. NUTRITIONAL AGENTS

8. SOCIAL AGENTS

9. OTHERS Hormones Lack of part or structure Chromosomal factors Immunological factors

10. HOST Human being is referred to as “ soil” and the disease agent as “ seed”

11. DEMOGRAPHIC FACTORS

12. BIOLOGICAL FACTORS

13. SOCIO ECONOMIC FACTORS

14. LIFE STYLE FACTORS

15. ENVIRONMENTAL FACTORS 1. PHYSICAL ENVIRONMENT

16. BIOLOGICAL ENVIRONMENT

17. PSYCHO SOCIAL ENVIRONMENT