# Situation: A public health nurse in a rice-farming municipality reviews a published prospective cohort study of farmers before planning leptospirosis prevention with the local farmers' association. The nurse has already judged the study to be well designed. Before applying its findings to her municipality, which question should she consider MOST important?

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> subject: Nursing Practice I — Community Health Nursing

## 문제

Situation: A public health nurse in a rice-farming municipality reviews a published prospective cohort study of farmers before planning leptospirosis prevention with the local farmers' association.

The nurse has already judged the study to be well designed. Before applying its findings to her municipality, which question should she consider MOST important?

## 보기

1. Did the study enroll several thousand farmers?
2. Were the farmers and fields like those in her area? **✔ 정답**
3. Was the study published in an international journal?
4. Was the study completed within the past two years?

**정답: 2**

## 해설

Once a study is judged valid, the key question for evidence-based practice is applicability: whether the study population and setting resemble the local population closely enough for the results to hold. Farming practices, flooding patterns, and rodent exposure may differ between areas. Where a study was published, its size beyond adequacy, and how recent it is do not by themselves decide whether it fits local practice.

## 심화 해설

The most important question is whether the study’s participants and environmental context resemble the nurse’s own municipality. A well-designed study can produce internally valid results, but those results only become useful for local decision-making when the population, exposure patterns, and setting are sufficiently similar.

Leptospirosis transmission depends heavily on local conditions. The bacterium is shed in the urine of infected reservoir animals—most often rodents—and survives in warm, moist environments such as flooded rice paddies, canals, and muddy soil. Farmers are exposed through skin abrasions or mucous membranes when working in contaminated water. However, the specific risk of infection varies with farming practices, water management, rodent density, and flooding frequency in each area. A cohort study conducted in one rice-farming region may reflect conditions that do not exist in another, even if both are classified as agricultural.

The evidence base reinforces this point. Studies examining occupation as a risk factor for leptospirosis have shown that occupational exposure is not uniform across regions. For example, surveillance-based analyses in Brazil have described occupation as an associated risk factor, but the authors note that reporting patterns and notification capacity differ by area, which can distort apparent risk [1]. Similarly, a case-control study in Kebumen, Indonesia identified local determinants of leptospirosis and mapped incidence specifically within that endemic setting [2]. Those determinants—such as proximity to rice fields, presence of rats, or use of protective equipment—may not transfer directly to a different municipality with different agricultural and environmental characteristics.

Long-term surveillance data from Fujian, China also illustrate how epidemiological patterns of leptospirosis shift over time and across locations, with reservoir animal distribution and human case trends varying by region [3]. A study in northern Iran further demonstrated that risk factors for leptospirosis were tied to local environmental and behavioral conditions in Golestan Province [4]. None of these studies suggests that a single set of risk factors applies universally to all farming communities.

Key point! External validity—also called applicability or generalizability—is the central concern when moving from research evidence to local practice. The nurse must ask whether the farmers in the study resemble the farmers in her municipality in terms of exposure intensity, environmental contamination, and rodent ecology.

The other options do not address this core issue. Several thousand participants may improve statistical precision, but a large sample does not make results applicable to a different population. Publication in an international journal speaks to peer review and visibility, not to local fit. Recency within two years matters for currency of evidence, but a recent study conducted in a dissimilar setting is still less useful than an older study conducted in a comparable one.

Watch out! Do not confuse internal validity—whether the study was conducted correctly—with external validity—whether the findings apply to your patients. The nurse has already judged the study to be well designed, so the remaining question is applicability.

The nurse should therefore prioritize comparing the study’s population and environmental context with her own municipality. If farming practices, flooding patterns, or rodent exposure differ substantially, the study’s findings may not predict local risk accurately, and prevention strategies may need adaptation.References (research sources)

- [1]Occupation as an associated risk factor for leptospirosis.Research articleMachado CD, Kmetiuk LB, Sibim AC, Biondo LM, Chiba de Castro WA, Biondo AW. (2026) · DOI: 10.3389/fpubh.2026.1810977

- [2]DETERMINANTS AND MAPPING OF LEPTOSPIROSIS IN KEBUMEN, INDONESIA: CASE-CONTROL STUDY.Research articleRahayu LM, Fajaria N, Arga B, Chandrayani S. (2025) · DOI: 10.21010/ajidv19i2.6

- [3]Epidemiological characteristics of leptospirosis and serological surveillance among reservoir animals and healthy populations in Fujian, China, 2004-2024.Research articleXu G, Li Y, Liu W, Han T, Zeng Z, Huang L, He F, Nian Y, Hu S, Lin F, Wu S, Xiao F. (2026) · DOI: 10.3389/fpubh.2026.1891639

- [4]Investigation of Risk Factors Associated with Leptospirosis in the North of Iran (2011-2017).Research articleSahneh E, Delpisheh A, Sayehmiri K, Khodabakhshi B, Moafi-Madani M (2019)

## 임상 시나리오

Applying Research to Local PracticeAssessing applicability before implementing evidence
After confirming a study is valid, the next step is judging applicability: are the study population and setting similar enough to your own? For leptospirosis, compare farming practices, flooding patterns, and rodent exposure between the study site and your municipality.

Leptospirosis risk is highly local. The bacteria survive in warm, moist environments such as flooded rice paddies and muddy soil, and farmers are exposed through skin abrasions or mucous membranes during work in contaminated water. Differences in water management or rodent density can change risk substantially.

CautionDo not assume that a study conducted in one rice-farming region applies to another. Publication venue, large sample size, and recent completion do not by themselves establish local fit.

## 핵심 개념

- **Applicability** — The extent to which study findings can be expected to hold in a different population or setting.
- **External validity** — The degree to which study results can be generalized beyond the specific study sample and context.
- **Leptospirosis** — A bacterial zoonosis transmitted through contact with water or soil contaminated by infected animal urine, often rodents.
- **Prospective cohort study** — A study design that follows a group over time to compare outcomes between exposed and unexposed participants.
- **Reservoir host** — An animal species that harbors a pathogen without severe illness and serves as a source of infection.

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