The Chain of Infection

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The Chain of Infection
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As healthcare professionals, it is important to
understand two things about infection
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1. the various ways infection can be transmitted

2. the ways the infection chain can be broken
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Types of Infections

• Endogenous
• Infection or disease originates within the body
• Examples Congenital (present at birth) and
  tumors

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Types of Infections

• Exogenous
• Infection or disease originates outside the body
• Examples pathogenic organism that invade the
  body, trauma, and radiation

• Nosocomial
• Infection acquired by a person in a health care
  facility or long-term care facility.
• Examples Staphylococcus and pseudomonas

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Types of Infection

• Opportunistic
• Infections that occur when the bodys defenses
  are weak.
• These infections do not usually occur if people
  have intact immune systems.
• Examples Pneumocystis Pneumonia in individuals
  with AIDs

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There are six links in the chain of infection
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1st - The Infectious Agent
-any disease-causing microorganism
(pathogen) Bacteria, Protozoa, Fungi, Rickettsia,
Viruses, Helminths
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2nd - The Reservoir Host
-the organism in which the infectious microbes
reside
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2nd - The Reservoir Host

• Human Body
• Animals
• Environment
• Fomites - objects contaminated with infectious
  material that contains the pathogens
  (doorknobs,bedpans, instruments)

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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.
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3rd - The Portal of Exit
-route of escape of the pathogen from the
reservoir in which it has been growing
Examples respiratory secretions, blood exposure,
breaks in skin
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3rd The Portal of Exit

• Ways pathogens can leave the body
• Urine and Feces
• Saliva
• Blood
• Tears
• Mucus Discharge
• Sexual Secretions
• Draining Wound

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4th - The Route of Transmission
-method by which the pathogen gets from the
reservoir to the new host
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Transmission may occur through
direct contact person to person
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air
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insects
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Food
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5th - The Portal of Entry
-route through which the pathogen enters its new
host
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Respiratory System
inhalation
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Gastrointestinal System
ingestion
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Urinary Reproductive Tracts
Sexual contact
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Breaks in Protective Skin Barrier
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6th - The Susceptible Host
-the organism that accepts the pathogen
The support of pathogen life its reproduction
depend on the degree of the hosts resistance.
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Organisms with strong immune systems are better
able to fend off pathogens.
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Organisms with weakened immune systems are more
vulnerable to the support reproduction of
pathogens.
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• Cancer Patients
• AIDS Patients
• Transplant Patients
• Infant Elderly Patients

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Remember--breaking the chain of infection is the
responsibility of each health professional.