The Chain of Infection Infectious Agent

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.

The Chain of Infection Infectious Agent Reservoir Host

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).

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.

The Chain of Infection Infectious Agent Reservoir Host Portal of Exit

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

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

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

Transmission may occur through: Direct Contact

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

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

Droplet

Transmission may occur through: Indirect Contact

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

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

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

Vector – organism that transmits pathogen from one host to another

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

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

Respiratory System inhalation

Gastrointestinal System ingestion

Urinary & Reproductive Tracts Sexual contact

Breaks in Protective Skin Barrier

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

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.

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

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

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