3.1.3 Modes of Transmission (Part 1)

Means of Transmission

​Transmission in a health care setting refers to the passing of a pathogen causing communicable disease from an infected host individual or group to a particular individual or group

3.1.3 Modes of Transmission

Part 1 - Chain of Infection

Open Ended

What are ways a pathogen can be transmitted from one individual or thing to an uninfected individual?

Means of Transmission

​Direct contact

​

​Airborne

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​Injection

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​Ingestion

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​Indirect contact

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​Vector

Multiple Choice

Transmission by inhaling microorganisms such as tuberculosis

• ingestion

• vector

• airborne

• direct contact

Multiple Choice

Transmission by touching a person with an infected wound

• vector

• direct contact

• indirect contact

• injection

Multiple Choice

Transmitted from a nonliving object such as a doorknob

• vector

• indirect contact

• direct contact

• injection

Multiple Choice

Transmission by means of eating of drinking contaminants.

• Vector

• Injection

• Ingestion

• airborne

Means of Transmission

​Direct contact by touching a person with an infected wound

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​Airborne transmission by inhaling microorganisms such as tuberculosis

​

​Injection of bloodborne transmission through blood and other body fluids

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​Ingestion by means of eating or drinking contaminants

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​Indirect contact transmitted from a nonliving object such as a doorknob

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​Vector transmission from an insect such as lyme disease from a tick

Chain of Infection

​

The spread of an infection is described as a “chain,” several interconnected steps that describe how a pathogen moves about.

​

​For an infection to develop, each link of the chain must be connected. Breaking any link of the chain can stop the transmission of infection!

Chain of Infection

Chain of Infection

Multiple Choice

What part of the chain is seen in this photo?

• Reservoir

• Portal of Entry

• Susceptible Host

• Mode of Transmission

Multiple Choice

What part of the chain is seen in this photo?

• Reservoir

• Portal of Exit

• Susceptible Host

• Pathogen

Multiple Choice

• Reservoir

• Portal of Entry

• Mode of Transmission

• Susceptible Host

Multiple Choice

What part of the chain is seen in this photo?

• Portal of Exit

• Susceptible Host

• Pathogen

• Portal of Entry

Multiple Choice

What part of the chain is seen in this photo?

• Pathogen

• Portal of Entry

• Susceptible Host

• Reservoir

Multiple Choice

What part of the chain is seen in this photo?

• Reservoir

• Susceptible Host

• Mode of Transmission

• Portal of Exit

Refining your hypothesis

In the previous activity, you wrote a hypothesis about which category, or categories, of infectious agent could be causing the infections seen in the hospital patients. For each category of agent you suspect to be causing the infection, work with your investigative team and record the possibilities for the:

Reservoir in the hospital | Portal of exit from the reservoir | Mode of transmission | Portal of entry into a host

Drag and Drop

The pathogen that most likely is causing the disorder in the 11 hospital patients is a

Placeholder

.

Drag these tiles and drop them in the correct blank above

bacteria

virus

fungus

prion

• Reservoir in the hospital

  • A patient or member of staff

  • A shared resource

  • A shared location

• Portal of exit from the reservoir

  • Skin

  • Gastrointestinal

​Possible answers

• ​Mode of transmission

  • Direct by touch or droplets

  • Indirect by vehicle (a tool)

• Portal of entry into a host

  • Skin

  • Gastrointestinal

Infectious Dose

A pathogen is more dangerous if fewer of them cause disease...

The number of organisms it takes to cause illness following exposure is known as the infectious dose.

Multiple Choice

The infectious dose of Ebola is 1-10 viruses, whereas Influenza A requires more than 790 viruses to infect a new host. Which of these viruses are considered more infectious?

• Ebola

• Influenza A

SARS-CoV-2 currently has an R₀ value of 4.22

It has been as high as 9.4

Open Ended

How could we break the chain of infection with SARS-CoV-2?