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

2. EPIDEMIOLOGICAL TRIAD
ENVIRONMENT
AGENT HOST

3. 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.

4. BIOLOGICAL AGENTS
• VIRUS
• BACTERIA
• PROTOZOVA
• FUNGUS
CHARACTERISTICS:
- Infectivity
- Pathogenicity
- virulence

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

6. CHEMICAL AGENTS
• ENDOGENOUS • EXOGENOUS

7. MECHANICAL AGENTS

8. NUTRITIONAL AGENTS

9. SOCIAL AGENTS

10. OTHERS
• Hormones
• Lack of part or structure
• Chromosomal factors
• Immunological factors

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

12. DEMOGRAPHIC FACTORS

13. BIOLOGICAL FACTORS

14. SOCIO ECONOMIC FACTORS

15. LIFE STYLE FACTORS

16. ENVIRONMENTAL FACTORS
1. PHYSICAL ENVIRONMENT

17. BIOLOGICAL ENVIRONMENT

18. PSYCHO SOCIAL ENVIRONMENT