The first person becoming sick in an epidemic is called?

Appeared in: PGIMER NO - 2020

Explanation

The primary case is defined as the first individual who acquires a communicable disease and introduces it into a population group.
This person represents the initial source of the infection for the subsequent outbreak.
The question specifically asks for the 'first person becoming sick', which directly corresponds to the definition of the primary case.

Option B: Secondary cases are individuals who contract the infection from the primary case. They are subsequent cases in the chain of transmission, not the first one.
Option C: 'Contract case' is not a recognized or standard term in epidemiology. The correct term is 'contact', which refers to a person who has been exposed to an infected individual, but this is not a type of case.
Option D: The index case is the first case that comes to the attention of investigators or health authorities. This is not necessarily the same as the primary case, as the true first person who got sick may have recovered, died, or never been identified.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Epidemiological Terminology: Differentiating Primary, Index, and Secondary Cases as background academic context rather than a clinical decision trigger.
Distinguishing between the primary and index case is critical for epidemiologists during outbreak investigations to accurately map the disease's spread.
Identifying the true primary case (Patient Zero) helps in understanding the origin of the outbreak and implementing targeted control measures like contact tracing more effectively.
What if? If the primary case is also the index case and is identified quickly, public health officials can contain the outbreak much faster by isolating the individual and tracing their contacts from the very beginning of the transmission chain.

How to Approach the Question

Recognize that this is a factual recall question requiring knowledge of standard epidemiological definitions.
Carefully analyze the question's key phrase: 'first person becoming sick'.
Recall the precise definitions of the terms in the options: Primary case, Secondary case, and Index case.
Critically differentiate between 'primary case' (the first person to fall ill) and 'index case' (the first person identified by authorities).
Eliminate 'Secondary case' as these are subsequent infections, and 'Contract case' as it's not a standard term.
Select the option that perfectly matches the definition of the first person to get sick.

Concept Tested & Keywords

Concept Tested: Epidemiological Terminology: Differentiating Primary, Index, and Secondary Cases
Stem keywords: first person, sick, epidemic
Lead-in keywords: is called
Negative lead-in flag: false

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E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart A (pp 26-201 of 604) p. 88-90

Practise the full PGIMER NO - 2020

Attempt every question from this paper in a timed mock, then review the full solution for each one.