Community Health II: Main Exam, 1 April 2021

Mount Kenya University · Department of Community Health · Diploma in Community Oral Health, Diploma in Health Records and Information Technology, Diploma in Clinical Medicine · DPH2103

Community Health II past paper from Mount Kenya University 2020-2021 with model answers for epidemiology and public health questions

Instructions: ANSWER ALL QUESTIONS IN SECTION A AND ANY OTHER TWO FROM SECTION B

SECTION A

1. Explain the meaning of the following terms used in epidemiology. (5 marks)

  1. a) Quarantine
    Model answer
    • Quarantine: Restriction of movement of persons who have been exposed to a contagious disease but are not yet ill, to see if they develop symptoms and prevent spread.
  2. b) Isolation
    Model answer
    • Isolation: Separation of individuals who are confirmed to be infected with a contagious disease from healthy persons to stop transmission.
  3. c) Surveillance
    Model answer
    • Surveillance: Ongoing systematic collection, analysis and interpretation of health data to monitor disease occurrence and guide public‑health action.
  4. d) Vaccination
    Model answer
    • Vaccination: Administration of a biological preparation that stimulates an individual's immune system to develop protective immunity against a specific pathogen.
  5. e) Epidemic
    Model answer
    • Epidemic: Occurrence of a disease in a community or region at a level that exceeds the expected baseline or usual frequency.

2. Describe the differences between clinical focus (clinician) and epidemiological focus (epidemiologist). (5 marks)

Model answer
  • Clinical focus (clinician)
  • Treats individual patients, emphasizes diagnosis, management and cure of disease in a single person.
  • Uses detailed patient history, physical exam and investigations.
  • Outcomes measured at patient level (recovery, morbidity, mortality).
  • Interventions are therapeutic (drugs, surgery) and preventive (counselling).
  • Epidemiological focus (epidemiologist)
  • Studies disease patterns in populations, seeks causes and risk factors.
  • Relies on population‑based data, surveys, surveillance systems.
  • Outcomes measured at group level (incidence, prevalence, attack rates).
  • Interventions are preventive at community level (vaccination programmes, health policies).

3. Describe the uses of epidemiology. (5 marks)

Model answer
  • Disease surveillance: monitoring incidence and prevalence to detect outbreaks.
  • Risk factor identification: studying associations between exposures and health outcomes.
  • Evaluation of interventions: assessing effectiveness of control measures and programs.
  • Planning and resource allocation: providing data for health policy and service planning.
  • Hypothesis generation: formulating questions for further analytical studies.
  • More answers: informing health education and guiding research priorities.

4. If you want to know the number of people in your ward who are properly using latrines, which method of data collection would be appropriate? And why? (5 marks)

Model answer
  • Method: Direct observation (spot check) of households.
  • Why: Provides objective, real‑time evidence of latrine use, minimizes recall bias, and allows verification of proper technique.

5. As an epidemiologist explain the relationship between environment, host and the agent. (5 marks)

Model answer
  • Agent: The pathogen (virus, bacteria, parasite) that can cause disease.
  • Host: Human characteristics (immunity, age, nutrition) that affect susceptibility.
  • Environment: Physical, social and ecological conditions that influence agent survival and host exposure.
  • Interaction: The agent must encounter a susceptible host in a conducive environment for transmission.
  • More answers: Changes in any component alter disease occurrence (e.g., improved sanitation reduces environmental exposure).

6. Outline the Common Characteristics of Communicable Diseases. (5 marks)

Model answer
  • Infectivity: Ability of the pathogen to establish infection.
  • Transmissibility: Ease of spread from one host to another.
  • Incubation period: Time between exposure and onset of symptoms.
  • Reservoir: Host or habitat where the agent persists.
  • Mode of transmission: Direct, indirect, vector‑borne, etc.
  • More answers: Ability to cause disease (pathogenicity) and susceptibility of the population.

7. Illustrate the 5W's of descriptive epidemiology. (5 marks)

Model answer
  • Who: Description of affected persons (age, sex, occupation).
  • What: Type of disease or health event (symptoms, diagnosis).
  • When: Time variables – date of onset, epidemic curve.
  • Where: Geographic location – place of residence, workplace.
  • Why (How): Initial hypotheses on source and mode of transmission.
  • More answers: May include “How many” (magnitude) as part of “What”.

8. Explain how you would control rodents in a village community. (5 marks)

Model answer
  • Environmental sanitation: Remove food sources and hideouts (clean up waste, store food securely).
  • Physical barriers: Seal cracks, install rodent‑proof doors and windows.
  • Trapping: Use snap or live traps in strategic locations.
  • Chemical control: Apply rodenticides in bait stations following safety guidelines.
  • Community education: Teach residents about proper waste management and storage.
  • Monitoring: Regular inspection and record‑keeping of rodent activity.
  • More answers: Biological control (predators) and habitat modification (reduce vegetation).

SECTION B

9. You have been posted to Naivasha Sub-County as a Sub-County Epidemiologist. A group of Community Health students have come to your office and their supervisor requests you to share your knowledge and experience in disease outbreak investigations. Highlight the main procedures of conducting a disease outbreak investigation. (15 marks)

Model answer
  • Verify the outbreak: Confirm that the number of cases exceeds expected baseline and that a common source or exposure is likely.
  • Define and identify cases: Develop a case definition (person, place, time, clinical criteria) and use it to find cases.
  • Establish a line‑list: Record each case’s details (name, age, sex, address, onset date, symptoms, exposure history, outcome).
  • Describe the outbreak: Create epidemic curves, spot maps and calculate attack rates to understand time, place and person patterns.
  • Generate hypotheses: Based on descriptive data, propose possible sources, modes of transmission and risk factors.
  • Conduct analytical studies: Use case‑control or cohort designs to test hypotheses; calculate odds ratios or relative risks.
  • Collect and test specimens: Obtain appropriate clinical/laboratory samples to identify the etiologic agent.
  • Implement control measures: Apply immediate interventions (e.g., isolation, vaccination, water treatment, health education) to stop transmission.
  • Communicate findings: Share results with health authorities, community leaders and the public through reports and briefings.
  • Monitor and evaluate: Continue surveillance to assess effectiveness of control actions and detect new cases.
  • Document the investigation: Prepare a detailed report covering methods, results, conclusions and recommendations.
  • Review and update preparedness: Recommend improvements to surveillance systems, outbreak response plans and training.
  • Coordinate with partners: Work with local hospitals, labs, NGOs and government agencies for resources and support.
  • Provide feedback to stakeholders: Offer debriefings to the community, health workers and policy makers.
  • Plan for post‑outbreak activities: Conduct after‑action reviews, reinforce health education and restore normal services.

10. Explain the difference between Community diagnosis and Clinical diagnosis. (15 marks)

Model answer
  • Community diagnosis: Assessment of health problems and needs of a defined population using epidemiological data, surveys and environmental scans; focuses on prevalence, risk factors and social determinants.
  • Clinical diagnosis: Determination of disease in an individual patient based on history, physical examination, and diagnostic tests; aims to identify the specific pathology affecting that person.
  • Scope: Community diagnosis is population‑level, guiding public‑health planning; clinical diagnosis is individual‑level, guiding patient management.
  • Data sources: Community diagnosis uses aggregated data (surveys, registries, mortality records); clinical diagnosis uses patient‑specific data (lab results, imaging, clinical signs).
  • Outcome: Community diagnosis leads to interventions such as health promotion, policy changes, and resource allocation; clinical diagnosis leads to treatment, therapy and patient counseling.
  • Time frame: Community diagnosis often looks at trends over months‑years; clinical diagnosis addresses the current presenting complaint.
  • Stakeholders: Community diagnosis involves public‑health officials, community leaders, NGOs; clinical diagnosis involves physicians, nurses, allied health professionals.
  • Goal: Reduce disease burden in the community vs. cure or manage disease in an individual.
  • Methodology: Uses epidemiologic tools (cross‑sectional studies, GIS mapping); uses diagnostic algorithms, differential diagnosis, and clinical reasoning.
  • Responsibility: Public‑health practitioners conduct community diagnosis; clinicians conduct clinical diagnosis.
  • Intervention level: Primary and secondary prevention at community level; therapeutic interventions at clinical level.
  • Feedback loop: Community diagnosis informs health policy which may affect clinical practice; clinical findings can signal emerging trends for community diagnosis.
  • Examples: High prevalence of hypertension in a district (community) vs. a patient with elevated BP diagnosed as essential hypertension (clinical).

11. Using examples explain at least FIVE types of Non-Probability Sampling. (15 marks)

Model answer
  • Convenience sampling: Selecting participants who are easiest to reach, e.g., recruiting patients from a clinic waiting area.
  • Judgment (purposive) sampling: Choosing subjects based on the researcher’s knowledge, e.g., selecting key informants who have expertise on a health issue.
  • Quota sampling: Setting quotas for sub‑groups and recruiting until each quota is filled, e.g., 30 males and 30 females from a community.
  • Snowball sampling: Existing participants refer other eligible participants, useful for hidden populations like drug users.
  • Systematic sampling (non‑random): Selecting every kth individual from a list without random start, e.g., every 5th household on a street.
  • More answers:
  • Volunteer sampling: Relying on individuals who self‑select to participate.
  • Expert sampling: Recruiting only those with specific expertise or experience.
  • Quota‑stratified sampling: Combining quota with stratification to ensure representation of sub‑groups.
  • Purposive maximum variation sampling: Selecting cases that capture a wide range of variation on certain characteristics.

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