1. The Chain of Infection
Infectious Agent

2. 1st - The Infectious Agent
Any disease-causing microorganism (pathogen)
May be cultured on agar plates and identified by Medical Laboratory Scientist in a clinical laboratory.

3. The Chain of Infection
Infectious Agent
Reservoir Host

4. Place in where the pathogen currently resides.
2nd - The Reservoir Host
Place in where the pathogen currently resides.
Could be in human or animals hosts, the environment or on fomites (inanimate objects).

5. What are “Carrier Hosts”
Hosts that do not show any outward signs or symptoms of a disease but are still capable of transmitting the disease are known as carriers.

6. The Chain of Infection
Infectious Agent
Reservoir Host
Portal of Exit

7. Route of escape for the pathogen from the reservoir.
3rd - The Portal of Exit
Route of escape for the pathogen from the reservoir.
Examples: respiratory secretions, bleeding, wound drainage, saliva in from animal/insect bites

8. The Chain of Infection Infectious Agent Reservoir Host Portal of Exit
Mode of Transmission

9. 4th - The Route of Transmission
Method by which the pathogen gets from the reservoir to the new host

10. Transmission may occur through:
Direct Contact

11. Direct Contact Touching infected blood/body fluids or open lesions
Kissing
Sexual Activity

12. DROPLET
Sneezing, coughing, talking or laughing spreads infected droplets into the air. Quickly fall out of air.
Usually contagious within 3 feet of person.

13. Droplet

14. Transmission may occur through:
Indirect Contact

15. INDIRECT CONTACT Frequent touch surfaces (fomites) such as: Door knobs
Cell phones
Tables/chairs/desks
Sinks/bathrooms
Medical equipment

16. AIRBORNE
Airborne transmission refers to situations where droplet nuclei (residue from evaporated droplets) or dust particles containing microorganisms can remain suspended in air for long periods of time..
Can survive long periods for long periods of time.
Fortunately, only a limited number of diseases are capable of airborne transmission

17. Fecal-Oral
Pathogens enter via oral to digestive tract – after having exited via feces.
Sources are contaminated water, food, shellfish

18. Vector – organism that transmits pathogen from one host to another

19. The Chain of Infection Infectious Agent Reservoir Host Portal of Exit
Portal of Entry
Mode of Transmission

20. Route through which the pathogen enters its new host
5th - The Portal of Entry
Route through which the pathogen enters its new host

21. Respiratory System
inhalation

22. Gastrointestinal System
ingestion

23. Urinary & Reproductive Tracts
Sexual contact

24. Breaks in Protective Skin Barrier

25. The Chain of Infection Infectious Agent Reservoir Host
Susceptible Host
Portal of Exit
Portal of Entry
Mode of Transmission

26. 6th - The Susceptible Host
The organism that accepts the pathogen
The support of pathogen life & its reproduction depend on the degree of the host’s resistance.

27. Organisms with strong immune systems are better able to fend off pathogens.

28. Organisms with weakened immune systems are more vulnerable to the support & reproduction of pathogens.

29. Example of Immune Compromised Patient
Cancer Patients on chemotherapy
AIDS Patients
Transplant Patients on immune system suppressing drugs
Infant & Elderly Patients
Trauma or massive burn patients
Critically or chronically ill patients