Epidemiology sounds technical, but the core idea is simple: it is how nurses and public health teams work out who is falling ill, where and when it is happening, why it is happening, and what to do about it. This guide covers the basics a Post RN BSN student needs and shows where the topic sits in the Pakistan Nursing Council's Post RN BSN curriculum.
Published: 12 October 2026 | Last verified: 12 October 2026
POST RN BSN Nursing Resources is an independent educational site. It is not affiliated with PNMC, LUMHS or any other institution. Always confirm your own syllabus, course outline and exam rules with your institute.
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| Epidemiology basics at a glance. Course details come from the 2019 PNC Post RN BSN curriculum; verify current details with your institute and official sources. |
Where epidemiology fits in the Post RN BSN curriculum
Historical document: The Pakistan Nursing Council (PNC) published a Post RN BSN curriculum (the file name carries the date 29.10.2019), which is now hosted on the PNMC website. In it, epidemiology appears as course SC 623.
Current status: The council is now called the Pakistan Nursing and Midwifery Council (PNMC). Its website says the Pakistan Nursing Council Act was amended in 2023 (Act No. V of 2023, amended on 19 January 2023) and that PNMC adopted the earlier PNC regulations and decisions at its first meeting on 8 August 2023. Whether PNMC has issued a newer Post RN BSN curriculum that replaces the 2019 document could not be verified.
What the 2019 PNC curriculum says about the epidemiology course
| Item | As printed in the curriculum |
|---|---|
| Course code and title | SC 623. The scheme table calls it "Epidemiology"; the course grid calls it "Introduction to Epidemiology". |
| Credit hours | 2 credits, all theory |
| Placement | Year I, Semester II |
| Evaluation listed | Group presentation 30%, midterm and quizzes 30%, final examination 40%. The same grid also mentions two home assignments of 10% each without saying how they fit into the 100%, so confirm the exact split with your institute. |
| Reference books listed | Leon Gordis (2009), 4th edition; I. M. Ansari, Community Medicine and Public Health (2003), 6th edition. Newer editions may exist; that could not be verified. |
The course description says the aim is to help learners use epidemiological concepts to assess contributing factors, plan interventions and evaluate results in the health care system, to understand how population changes affect social and health status in Pakistan, and to link epidemiological research findings to nursing practice.
The grid breaks the course into ten units:
- Introduction of Epidemiology
- Concept of Health and Disease
- Natural History of Disease (host, agent and environment, the epidemiological triad)
- Concept of Levels of Prevention (primary, secondary and tertiary)
- Epidemiological transitions in disease patterns
- Basic Measurement of Epidemiology (rates, ratios, incidence, prevalence, 2×2 tables, odds ratio, relative risk, attributable risk)
- Epidemiological Methods (descriptive and analytic designs, bias and confounding)
- Surveillance (quality) and Notification of Communicable Diseases
- Screening and Outbreak Investigation
- Data Management and Presentation
Institutions can place or name the course differently. For example, one university's published Post RN BS Nursing scheme of studies (on fush.fui.edu.pk) lists "Intro to Epidemiology", 2 credits, in Year II, Semester III, while the PNC grid places it in Year I, Semester II. For LUMHS, a published Post RN BSN scheme of studies or epidemiology course listing could not be found on its official website, so how LUMHS teaches this course could not be verified. Ask your department for the current course outline.
What is epidemiology?
The CDC's Principles of Epidemiology course describes epidemiology as the systematic study of how health-related states and events are distributed in specified populations, what determines them, and how that knowledge is applied to control health problems. The word comes from Greek roots meaning "on or upon", "people" and "the study of". Each part of that description has a practical meaning:
- Distribution: the frequency of a health event (counts related to the size of the population, which gives a rate) and its pattern by time, place and person.
- Determinants: the causes and other factors that influence whether a health event occurs. Epidemiologists work on the assumption that illness does not occur randomly in a population.
- Health-related states or events: not only infectious disease. The field expanded to chronic disease, injuries, birth defects, occupational and environmental health, and behaviours such as exercise or seat belt use.
- Specified populations: the clinician's patient is the individual, while the epidemiologist's "patient" is the community.
- Application: findings are used to propose practical interventions that control and prevent disease.
Here is the difference in practice. When a patient with diarrhoeal illness presents, both the clinician and the epidemiologist want the correct diagnosis. The clinician then focuses on treating the individual, while the epidemiologist asks what the source of exposure was, who else may have been exposed, whether the illness can spread further, and which interventions would prevent more cases.
Descriptive and analytic epidemiology
Descriptive epidemiology describes health events by time, place and person. Time patterns can be annual, seasonal, weekly or daily. Place patterns include geographic variation, urban and rural differences, and locations such as work sites or schools. Person characteristics include age, sex, socioeconomic status, behaviours and environmental exposures. Descriptive data are mainly used to generate hypotheses.
Analytic epidemiology tests those hypotheses and looks for the "why" and "how". Its key feature is a comparison group. The CDC adds an important caution: epidemiology by itself can never prove that a particular exposure caused a particular outcome, but it often provides enough evidence to take appropriate control and prevention measures.
Core measures every nursing student should know
| Measure | What it tells you | How it is calculated (CDC) |
|---|---|---|
| Incidence proportion (risk or attack rate) | The chance of developing the disease during a period | New cases during the period ÷ population at the start of the period |
| Incidence rate (person-time rate) | How quickly new cases occur | New cases ÷ total person-time observed |
| Secondary attack rate | Spread among contacts, for example within households | New cases among contacts ÷ total number of contacts |
| Point prevalence | Proportion of the population with the condition at one point in time | All current cases (new and existing) ÷ population at that time |
| Period prevalence | Proportion with the condition at any time in an interval | All cases during the period ÷ average or mid-interval population |
Incidence versus prevalence. The difference lies in the numerator: incidence counts only new cases, while prevalence counts all cases present, new and existing. Prevalence depends on both incidence and how long the illness lasts, so a high prevalence can reflect a high incidence, long survival without cure, or both. Prevalence is often measured for chronic diseases such as diabetes or osteoarthritis, where the date of onset is hard to pinpoint.
Worked example (from the CDC course). At a corporate picnic outbreak of gastroenteritis, 99 people ate potato salad and 30 of them became ill. The food-specific attack rate is 30 ÷ 99 = 30.3%.
Comparing groups: risk ratio and odds ratio
A risk ratio (relative risk) divides the risk in the group of interest, usually the exposed group, by the risk in the comparison group. A value of 1.0 means identical risk, above 1.0 means increased risk for the exposed group, and below 1.0 means decreased risk, which may point to a protective exposure.
The CDC example uses a tuberculosis outbreak among prison inmates in South Carolina in 1999. The exposure is the dormitory wing:
| Dormitory wing | Developed TB | Did not develop TB | Total | Risk |
|---|---|---|---|---|
| East wing (exposed) | a = 28 | b = 129 | 157 | 17.8% |
| West wing (unexposed) | c = 4 | d = 133 | 137 | 2.9% |
Risk ratio = 17.8% ÷ 2.9% = 6.1, so East wing residents were about 6.1 times as likely to develop tuberculosis as West wing residents.
An odds ratio is calculated as (a × d) ÷ (b × c). It is the measure of choice in a case-control study, where the population size is usually unknown and risks cannot be calculated. When the outcome is uncommon, the odds ratio approximates the risk ratio. In the CDC's hypothetical 10,000-person example the risk ratio is 5.0 and the odds ratio is 5.2. The more common the outcome, the further the two drift apart. For the tuberculosis table above, our own calculation gives (28 × 133) ÷ (129 × 4) = 7.2 compared with a risk ratio of 6.1.
The PNC grid also lists absolute risk, attributable risk and population attributable risk. These are not covered in depth here. See CDC Lesson 3, Section 6 (Measures of Public Health Impact) and your teacher's notes.
Terms for the level of disease in a population
- Sporadic: a disease that occurs infrequently and irregularly.
- Endemic: the constant presence or usual level of a disease in a population within a geographic area.
- Hyperendemic: persistent, high levels of disease.
- Epidemic: an increase, often sudden, in cases above what is normally expected in that population and area.
- Outbreak: the same definition as an epidemic, but often used for a more limited geographic area. Many epidemiologists use the two terms interchangeably, while the public is more likely to hear "epidemic" as a crisis.
- Cluster: cases grouped in place and time that are suspected to be more than expected, even when the expected number is not known.
- Pandemic: an epidemic that has spread over several countries or continents, usually affecting a large number of people.
Study designs at a glance
| Design | What the investigator does | Key point |
|---|---|---|
| Clinical or community trial (experimental) | Decides, through a controlled process, who gets the exposure, then follows the groups | For example, vaccine versus placebo |
| Cohort (observational) | Records whether each participant is exposed, then follows them to see who develops the disease | Compares disease rates in exposed and unexposed groups. Can be prospective or retrospective. |
| Case-control (observational) | Enrols people with the disease and a comparable group without it (controls), then compares past exposures | Uses the odds ratio. Choosing the control group well is the key challenge. |
| Cross-sectional (observational) | Measures exposure and outcome at the same time in a sample | Good for prevalence. Analytically weaker than cohort or case-control for finding causes. |
Bias matters most when choosing controls. The CDC defines it as a systematic difference between cases and controls that leads to a mistaken estimate of the link between exposure and disease.
The PNC grid says the group presentation asks students to design an epidemiological study from a scenario, and Year II of the scheme includes a research or evidence-based project. If you are planning either, read our guide on how to write a nursing research proposal to see how a study question, design and methods fit together.
Surveillance and outbreak investigation
Surveillance. The World Health Organization generally defines public health surveillance as the continuous, systematic collection, analysis and interpretation of health-related data needed to plan, implement and evaluate public health practice. In passive surveillance, a health department receives reports of illness. In active surveillance, staff contact clinicians and laboratories to look for cases. Unit 8 of the PNC grid also asks students to identify the nurse's role in surveillance and control of communicable diseases, and names DEWS as the practical example of surveillance in Pakistan. Details of DEWS could not be verified for this article.
Outbreak investigation. The CDC lists thirteen steps. It stresses that they are in conceptual order and that, in practice, several can happen at the same time or in a different order:
- Prepare for field work
- Establish the existence of an outbreak
- Verify the diagnosis
- Construct a working case definition
- Find cases systematically and record information
- Perform descriptive epidemiology
- Develop hypotheses
- Evaluate hypotheses epidemiologically
- As necessary, reconsider, refine and re-evaluate hypotheses
- Compare and reconcile with laboratory and/or environmental studies
- Implement control and prevention measures
- Initiate or maintain surveillance
- Communicate findings
Two points students often miss. First, a case definition is a standard set of criteria (clinical, plus time, place and person restrictions in an outbreak), and it must not include the exposure you are trying to test. Second, an epidemic curve, a histogram of cases by date of onset, shows the size and time course of an outbreak. A steep rise with a slower fall typically suggests a point-source exposure, while a series of rising peaks suggests person-to-person spread.
Study tips for exams and projects
- Practise building a 2×2 table and calculating risk, risk ratio and odds ratio until it feels automatic. The grid lists these skills explicitly.
- Learn the incidence versus prevalence difference with one clear example you can reproduce in an exam.
- Memorise the order of the outbreak investigation steps and be ready to explain why the order can flex.
- For the group presentation, choose a real health problem and state its time, place and person pattern before proposing a study design.
- Check whether your institute uses the PNC grid as printed or has its own revised outline.
Frequently asked questions
What is epidemiology in simple words?
It is the study of how often health problems occur in groups of people, what causes or influences them, and how that knowledge is used to prevent and control disease.
Is epidemiology part of the PNC Post RN BSN curriculum?
Yes. The 2019 PNC curriculum lists SC 623, Introduction to Epidemiology, as a 2-credit theory course in Year I, Semester II. Individual institutions may name or place it differently, so check your own scheme of studies.
What is the difference between incidence and prevalence?
Incidence counts new cases during a period, while prevalence counts all existing cases, new and old, at a point or over a period.
When is an odds ratio used instead of a risk ratio?
In case-control studies, where the size of the underlying population is not known, so risks cannot be calculated. The odds ratio is a good approximation of the risk ratio when the disease is uncommon.
Are an outbreak and an epidemic the same?
They share the same definition, an increase in cases above what is expected. "Outbreak" is often used for a more limited area, and many epidemiologists use the terms interchangeably.
Does LUMHS teach this course in the same way?
This could not be verified. No Post RN BSN scheme of studies or epidemiology course listing was found on the official LUMHS website. Ask your department for the current outline.
Related reading on this site
Official sources
- Pakistan Nursing Council, Post RN BSN curriculum (file dated 29.10.2019, hosted by PNMC): pnmc.gov.pk, Post-RN-BSN-29.10.2019.pdf (historical document)
- PNMC, About PNMC (current regulator information): pnmc.gov.pk/about-pnmc
- LUMHS official website (checked for a Post RN BSN scheme; none found): lumhs.edu.pk
- CDC archive, Principles of Epidemiology, Lesson 1, Section 1, Definition of Epidemiology (last reviewed 2012): archive.cdc.gov, Lesson 1 Section 1
- CDC archive, Lesson 1, Section 7, Analytic Epidemiology: archive.cdc.gov, Lesson 1 Section 7
- CDC archive, Lesson 1, Section 11, Epidemic Disease Occurrence: archive.cdc.gov, Lesson 1 Section 11
- CDC archive, Lesson 3, Section 2, Morbidity Frequency Measures: archive.cdc.gov, Lesson 3 Section 2
- CDC archive, Lesson 3, Section 5, Measures of Association: archive.cdc.gov, Lesson 3 Section 5
- CDC archive, Lesson 6, Section 2, Steps of an Outbreak Investigation (last reviewed 2016): archive.cdc.gov, Lesson 6 Section 2
- World Health Organization, WHO guidelines on ethical issues in public health surveillance (2017): who.int, publication page
- Example of an institution's published Post RN BS Nursing scheme of studies: fush.fui.edu.pk, scheme of studies
The CDC course pages are archived material that teach long-established concepts. Check current CDC or WHO guidance for disease-specific definitions, case definitions or data.
Verification reminder
Checked on 12 October 2026. The curriculum details come from the PNC document hosted on the PNMC website and may have been revised since. Institutions can adopt, adapt or reorder the course, so always follow your own institute's approved scheme of studies and syllabus.
Could not be verified: whether PNMC has issued a newer Post RN BSN curriculum than the 2019 document; how LUMHS lists or teaches epidemiology in its Post RN BSN; the current editions of the reference books; the details of DEWS; and the WHO surveillance wording directly from the WHO PDF (the WHO publication page was opened, but the definition was confirmed through a secondary quotation of the same guideline).
Epidemiology Basics for Nursing Students | POST RN BSN Nursing Resources
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