Outbreak CER submission

This is a worked model for a DIFFERENT outbreak than the one you must argue today. Use it to see how a CER is built, not to copy an answer.

Claim: The summer illnesses were most likely caused by a parasitic pathogen spread through contaminated water at the community swimming pool during the week of July 12.

Evidence:

• Signs and symptoms: swimmers had watery diarrhea (symptom) and low-grade fever (sign) that lasted more than a week, a pattern that fits a lingering gut infection rather than a quick one.
• Pathogen table: the long incubation period of about a week and the poor response to standard antibiotics point to a parasite, not bacteria or a virus.
• Relationship map: the sick swimmers had all used the same pool during the same week, and none of the people who stayed out of the water got sick, marking the pool as the common source.

Reasoning: Each piece of evidence narrows the cause. The drawn-out diarrhea and mild fever rule in a gut infection, the long incubation and antibiotic resistance rule in a parasite, and the shared pool exposure links the cases to one place and time. Together they support a waterborne parasitic outbreak.

Confirmatory test: collect stool samples from patients and a water sample from the pool, then examine both under a microscope and run PCR to confirm the same parasite species is present in both.