Diagram The Chain Of Infection
Use infection evidence to diagram the chain of infection step by step.
- Transmission basics: Outbreak work depends on agent, host, route, time, and place.
- Case definition: Students need a rule for who counts as a case before counting cases.
Prerequisites are inferred: pending teacher review.
Re-learn the skill with worked practice and clear examples.
Use infection evidence to diagram the chain of infection step by step.
Use the infection figure/table. Which evidence best supports a shared-source outbreak?
Reviewed- A.Several cases share the same exposure and close onset times
- B.One person is much sicker than the others, with no exposure recorded
- C.Cases with onset dates spread evenly over six weeks
- D.A large total case count, even when the exposures are all different
Show the worked solution ▾
Answer: A. Several cases share the same exposure and close onset times
- Step 1: Find shared exposure: A shared source means cases have a common exposure.
- Step 2: Check timing: Close onset times strengthen the pattern.
Why it's right: Shared exposure plus close timing supports a shared-source outbreak.
- B: How sick one person is does not show that other people shared a source.
- C: Onsets spread evenly over weeks fit person-to-person spread, not one source.
- D: A big count with different exposures points to many sources, not one.
Aligned to Biotechnology Research and Experiments · reading level ~grade 9
Direct contact means touching an infected person or their body fluids. Indirect contact means inhaling particles, touching an infected object, or being bitten by an insect. A patient falls ill after touching a doorknob an infected visitor had used. Which route is that?
Reviewed- A.Neither route, because a doorknob cannot hold an agent at all
- B.Indirect contact, because an object carried the agent between two people
- C.Direct contact, because the patient touched something with a bare hand
- D.Direct contact, because two people were involved in the spread
Show the worked solution ▾
Answer: B. Indirect contact, because an object carried the agent between two people
- Step 1: Find what stood between the two people: A doorknob, which is an object.
- Step 2: Match to the definitions: Touching an infected object is listed under indirect contact.
Why it's right: The two people never touched each other. The agent moved by way of an object, which is the definition of indirect contact.
- A: Objects can hold an agent for a period of time, which is why touching them counts as a route.
- C: Direct contact means touching the infected person, not touching any surface.
- D: Two people are involved in almost every route; what decides it is whether they touched each other.
Aligned to Biotechnology Research and Experiments · reading level ~grade 9
- In Unit 3.1 Nosocomial Nightmare, this skill turns class evidence into a result another person can check.
Fill these in as you work through the lesson.
- Pathogen (disease-causing agent):
- Transmission (how a pathogen spreads):
- Reservoir (where pathogen lives):
- Case (person who fits outbreak definition):
Track the , route of transmission, time pattern, and exposed before making an outbreak claim.
- Who fits the case definition?
- What exposure do cases share?
- What timing pattern appears?
Use the infection diagram or line list to practice diagram the chain of infection.