Question

reasoning practice: epidemiology & contract tracing
there was an outbreak of stec amongst the science teachers at a gateway potluck! all of the teachers were tested for stec after the potluck and the table below has the results.
use claim-evidence-reasoning to answer the following question:
who was the original person infected with stec at the gateway science teacher potluck?
claim (answer to the question)
evidence (data from the table above)
reasoning (explain why your evidence supports your claim) can continue on back

Explanation:

• Claim: Ms. P - T was the original person infected.
• Evidence #1: Ms. P - T tested positive (+).
• Evidence #2: Her sharing partner Mr. Little (who shared with her) also tested positive.
• Evidence #3: Mr. Little's other sharing partner Ms. Nolan (who shared with Mr. Little) tested positive.
• Reasoning: In an outbreak, if a person (Ms. P - T) tests positive and those who had direct or indirect contact (through sharing partners like Mr. Little and then Ms. Nolan) also test positive, it is likely that the first - positive - tested person (Ms. P - T) was the source. Since Ms. Geisse (one of Ms. P - T's partners) was negative, it could be that the infection spread from Ms. P - T to Mr. Little (as they were both positive) and then from Mr. Little to Ms. Nolan (both positive). There is no indication of a prior - infected person before Ms. P - T in the contact - tracing data provided.

Answer:

• Claim: Ms. P - T was the original person infected with STEC.
• Evidence #1: Ms. P - T's test result is (+).
• Evidence #2: Mr. Little (a sharing partner of Ms. P - T) has a (+) test result.
• Evidence #3: Ms. Nolan (a sharing partner of Mr. Little) has a (+) test result.
• Reasoning: The positive test results of those in direct (Mr. Little) and indirect (Ms. Nolan through Mr. Little) contact with Ms. P - T, along with no prior - positive - tested person in the contact - tracing data before Ms. P - T, supports the claim that Ms. P - T was the original infected person.