A study was done to identify the number of Typhoid cases due to exposure from a common well in the village large groups were formed of carriers and diseased people. What type of study design is represented here?

Appeared in: NORCET 3 - 2022 (Shift-1)

Explanation

A cohort study is an analytical, observational study where a group of individuals (the cohort) is followed over time.
The study proceeds from cause (exposure) to effect (outcome/disease). In this scenario, the exposure is the common well, and the outcome is Typhoid fever.
The question describes a classic retrospective cohort study, which is the standard approach for investigating an outbreak with a known exposure in a defined population.
Investigators would identify who drank from the well (exposed cohort) and who did not (unexposed cohort), and then compare the incidence of Typhoid in both groups to establish a link.

Option B: A cross-sectional study measures exposure and disease at the same time, providing a 'snapshot'. It cannot determine if exposure to the well water happened before the onset of Typhoid, which is necessary to establish a cause-and-effect relationship.
Option C: A case-control study works backward, from outcome to exposure. It would start by identifying people with Typhoid (cases) and without Typhoid (controls) and then investigate their past exposure to the well water. The question's focus on 'exposure from a common well' suggests the study is organized around the exposure, not the outcome.
Option D: A field trial is an experimental study, not an observational one. It involves applying an intervention (like a new vaccine or water purification system) to a healthy population to see if it prevents disease. The question describes an investigation into the cause of an existing outbreak.

*
*

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Epidemiological Study Designs as background academic context rather than a clinical decision trigger.
Nurses must understand different research designs to critically appraise evidence and apply it to practice. This knowledge is essential for evidence-based practice (EBP).
In community health nursing, identifying the correct study design helps in understanding and responding to outbreaks, implementing control measures, and educating the public.
What if the disease was very rare and the source was unknown? In that case, a case-control study would be more efficient. You would start with the few known cases and try to find a common exposure among them by comparing them to controls.

How to Approach the Question

First, identify the key elements in the scenario: the exposure (common well), the outcome (Typhoid cases), and the population (a village).
Next, determine the direction of the study. The phrase 'due to exposure from a common well' implies the study is organized around the exposure and is looking for the outcome. This is a forward direction (cause to effect).
Recall the definitions of the four study designs. A cohort study follows a group from exposure to outcome.
A case-control study goes backward, from outcome to exposure.
A cross-sectional study is a snapshot in time.
A field trial is an experimental intervention.

Concept Tested & Keywords

Concept Tested: Epidemiological Study Designs
Stem keywords: Typhoid cases, exposure, common well, study design
Lead-in keywords: What type of study
Clinical cues: Outbreak investigation linked to a common source (well) in a defined population (village).

QHDj8hni8CwiCU20KQ5ZEy

Practise the full NORCET 3 - 2022 (Shift-1)

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