Lesson Notes By Weeks and Term v3 - Junior Secondary 3
Pathogens, diseases and their prevention
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Pathogens, diseases and their prevention
Download the Lessonotes Mobile Nigeria 2025 app for faster lesson access on Android and iPhone.
Subject: Physical & Health Education
Class: Junior Secondary 3
Term: 3rd Term
Week: 12
Theme: Health Education
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explain the nature of communicable diseases; explain the mode of transmission of communicable diseases; list diseases factor and causative agents; explain the various preventive and management measures; explain the nature of non-communicable diseases; state how to prevent non communicable diseases.
Causative Agent (Pathogen Type) | | :---------------- | :------------------------------------ | :----------------------------------- | | Malaria | Mosquito bite (Vector-borne) | Plasmodium species (Protozoa) | | Typhoid Fever | Contaminated food/water (Vehicle-borne) | Salmonella typhi (Bacteria) | | Cholera | Contaminated water/food (Vehicle-borne) | Vibrio cholerae (Bacteria) | | Tuberculosis (TB) | Airborne droplets (Airborne/Droplet) | Mycobacterium tuberculosis (Bacteria) | | HIV/AIDS | Bodily fluids (Sexual, Blood, Vertical) | Human Immunodeficiency Virus (Virus) | | Measles | Airborne droplets (Airborne/Droplet) | Measles virus (Virus) | | Hepatitis B | Bodily fluids (Sexual, Blood, Vertical) | Hepatitis B virus (Virus) |
4. Preventive and Management Measures for Communicable Diseases: Prevention: Hygiene: Regular handwashing with soap and water (especially after using the toilet and before eating), proper food preparation and storage, personal cleanliness.
Sanitation: Proper disposal of waste, safe and clean water supply, construction and use of latrines/toilets, community clean-up exercises.
Immunization/Vaccination: Administering vaccines to provide immunity against specific diseases (e.g., polio, measles, diphtheria, tetanus, hepatitis B, yellow fever).
Vector Control: Use of insecticide-treated nets (ITNs) for malaria, indoor residual spraying, eliminating mosquito breeding sites (stagnant water), rodent control.
Safe Sexual Practices: Abstinence, fidelity, consistent and correct use of condoms to prevent STIs.
Isolation: Separating infected individuals to prevent further spread (e.g., during outbreaks).
Health Education: Creating awareness about disease causes, transmission, and prevention in schools and communities.
Safe Blood Transfusion: Screening blood donors and donated blood for infectious diseases.
Management: Early Diagnosis: Prompt medical consultation when symptoms appear.
Appropriate Treatment: Taking prescribed medications (antibiotics for bacterial infections, antivirals for viral, antimalarials for malaria) as directed by a healthcare professional.
Rehydration: Especially for diarrhoeal diseases like cholera (e.g., Oral Rehydration Salts – ORS).
Rest and Nutrition: Adequate rest and a balanced diet support the body's immune system.
Adherence to Medical Advice: Following doctor's instructions to ensure full recovery and prevent drug resistance.
D. Non-Communicable Diseases (NCDs): Nature and Prevention
1. Nature of Non-Communicable Diseases: They are chronic conditions, meaning they are long-lasting and generally progress slowly. They are not caused by pathogens and are not infectious. They result from a complex interaction of genetic predisposition, physiological factors (e.g., age), environmental influences (e.g., air pollution), and behavioural risk factors (e.g., unhealthy diet, physical inactivity, tobacco use, harmful use of alcohol).
Examples common in Nigeria: Hypertension (High Blood Pressure), Diabetes Mellitus, various Cancers, Asthma, Heart Diseases, Stroke, Sickle Cell Anaemia.
2. Prevention of Non-Communicable Diseases: Healthy Diet: Consuming a balanced diet rich in fruits, vegetables, whole grains, and lean proteins; reducing intake of processed foods, high sugar, high salt, and unhealthy fats.
Regular Physical Activity: Engaging in moderate-intensity exercise for at least 30 minutes most days of the week (e.g., brisk walking, jogging, cycling, dancing).
Avoidance of Tobacco Use: Quitting smoking or avoiding exposure to second-hand smoke significantly reduces the risk of cancer, heart disease, and respiratory illnesses.
Moderation of Alcohol Consumption: Avoiding excessive alcohol intake.
Stress Management: Practicing techniques like meditation, yoga, or engaging in hobbies to reduce stress levels.
Regular Health Check-ups and Screening: Early detection of risk factors or diseases allows for timely intervention and management (e.g., checking blood pressure, blood sugar, cancer screenings).
Maintaining a Healthy Weight: Preventing obesity through diet and exercise.
A. Pathogens: Pathogens are microscopic organisms that can cause disease. They are often referred to as 'germs'. Understanding pathogens is the first step in comprehending how diseases occur and spread.
Types of Pathogens: Bacteria: Single-celled microorganisms that can live almost anywhere. Some are beneficial, but others cause diseases like typhoid, cholera, tuberculosis, and tetanus.
Viruses: Much smaller than bacteria, viruses are not considered living organisms outside a host cell. They replicate by hijacking host cells and cause diseases like measles, influenza, HIV/AIDS, hepatitis, and COVID-
1
9. Fungi: Organisms like yeasts and molds. They can cause skin infections (e.g., ringworm, athlete's foot) and sometimes internal infections.
Protozoa: Single-celled organisms, larger than bacteria, often found in water or as parasites. Examples include Plasmodium (causes malaria) and Entamoeba histolytica (causes amoebiasis/dysentery).
B. Diseases: A disease is any abnormal condition that impairs physiological function in an organism. It is often associated with specific symptoms and signs.
Classification of Diseases: Communicable Diseases (Infectious Diseases): Diseases caused by pathogens that can be transmitted from one person to another, from animals to humans, or from the environment to humans. Non-Communicable Diseases (NCDs / Chronic Diseases): Diseases that are not caused by pathogens and cannot be spread from person to person. They are often long-lasting and result from a combination of genetic, lifestyle, and environmental factors.
C. Communicable Diseases: Nature, Transmission, Factors, and Prevention/Management
1. Nature of Communicable Diseases: They are infectious, meaning they are caused by living organisms (pathogens). They can spread from a source (infected person, animal, or contaminated environment) to a susceptible host. They often have an incubation period (time between exposure and symptom onset).
Examples common in Nigeria: Malaria, Typhoid, Cholera, Tuberculosis, HIV/AIDS, Measles, Hepatitis.
2. Mode of Transmission of Communicable Diseases: Direct Contact: Person-to-person: Through physical touch, kissing, sexual contact (e.g., STIs like HIV, syphilis), direct contact with bodily fluids (e.g., Lassa fever through contact with blood/urine of infected person).
Animal-to-person (Zoonotic): Contact with infected animals or their products (e.g., rabies from dog bite, Lassa fever from contact with rats or their droppings/urine).
Indirect Contact: Fomites: Contact with contaminated inanimate objects (e.g., doorknobs, shared towels, toys) used by an infected person (e.g., common cold, influenza, skin infections).
Droplet Transmission: When an infected person coughs, sneezes, or talks, releasing droplets containing pathogens that can be inhaled by others nearby (usually within 1-2 meters).
Examples: Influenza, common cold, tuberculosis (though TB also has an airborne component).
Airborne Transmission: Pathogens remain suspended in the air over longer distances as aerosols (tiny particles). Can be inhaled over longer distances or after the infected person has left the area.
Examples: Measles, Chickenpox, Tuberculosis (especially in poorly ventilated spaces).
Vector-borne Transmission: Insects or animals (vectors) transmit pathogens from an infected host to a susceptible one.
Example 1 (Malaria): The Anopheles mosquito acts as a vector, transmitting Plasmodium parasites from an infected person to a healthy person when it bites.
Example 2 (Typhoid/Cholera): Flies can mechanically transmit bacteria from faeces to food.
Vehicle-borne Transmission: Pathogens are transmitted through contaminated inanimate vehicles such as food, water, or blood. Example 1 (Cholera, Typhoid): Contaminated water supplies or food prepared in unsanitary conditions. Example 2 (Hepatitis B, HIV): Contaminated blood transfusions or shared needles.
Vertical Transmission: Transmission from an infected mother to her child during pregnancy, childbirth, or breastfeeding.
Examples: HIV, Hepatitis B, Syphilis.
3. Disease Factors and Causative Agents (Examples relevant to Nigeria): | Disease | Disease Factor / Mode of Transmission | Causative Agent (Pathogen Type) | | :---------------- | :------------------------------------ | :----------------------------------- | | Malaria | Mosquito bite (Vector-borne) | Plasmodium species (Protozoa) | | Typhoid Fever | Contaminated food/water (Vehicle-borne) | Salmonella typhi (Bacteria) | | Cholera | Contaminated water/food (Vehicle-borne) | Vibrio cholerae (Bacteria) | | Tuberculosis (TB) | Airborne droplets (Airborne/Droplet) | Mycobacterium tuberculosis (Bacteria) | | HIV/AIDS | Bodily fluids (Sexual, Blood, Vertical) | Human Immunodeficiency Virus (Virus) | | Measles | Airborne droplets (Airborne/Droplet) | Measles virus (Virus) | | Hepatitis B | Bodily fluids (Sexual, Blood, Vertical)
Teacher Activities: Introduction (10 minutes): Begin by asking students to name some common illnesses they or their family members have experienced in Nigeria. Lead a brief discussion on what makes people sick and if some sicknesses can spread. Introduce the topic "Pathogens, Diseases and their Prevention," highlighting its importance for their personal and community health.
Explanation of Key Concepts (25 minutes): Define pathogens and list their types (bacteria, viruses, fungi, protozoa) with relevant disease examples. Explain the difference between communicable and non-communicable diseases using a simple analogy or local examples. Elaborate on the nature and modes of transmission of communicable diseases using the provided examples (Malaria, Typhoid, HIV, TB). Utilize simple diagrams on the board or chart showing, e.g., mosquito life cycle or droplet spread. Discuss disease factors and causative agents for selected diseases, emphasizing Nigerian relevance. Explain preventive and management measures for communicable diseases, involving student input where possible.
Group Discussion & Activity (20 minutes): Divide students into small groups (4-5 students). Assign each group a specific communicable disease (e.g., Cholera, Measles, Hepatitis B) and instruct them to: Identify its mode of transmission. List three specific preventive measures applicable in a Nigerian home/community. Discuss how it can be managed. Facilitate group presentations and peer feedback. Explanation of Non-Communicable Diseases (15 minutes): Explain the nature of non-communicable diseases, stressing they are not infectious. List common NCDs in Nigeria (Hypertension, Diabetes, Cancer, Asthma). Discuss the key preventive measures, focusing on lifestyle choices. Practical Demonstration/Discussion (10 minutes): Demonstrate proper handwashing technique. Discuss the importance of proper food handling and storage in preventing food/water-borne diseases. Show a picture of an insecticide-treated net and discuss its use.
Conclusion (5 minutes): Summarize the key takeaways regarding communicable and non-communicable diseases and their prevention. Encourage students to be health ambassadors in their homes and communities.
Student Activities: Participate actively in brainstorming sessions and Q&A. Engage in group discussions to identify modes of transmission and prevention strategies for assigned diseases. Present their group findings to the class. Practice proper handwashing technique following the teacher's demonstration. Take notes and ask clarifying questions.
Question 1: Explain what communicable diseases are, providing one example commonly found in a Nigerian community.
Solution 1: Explanation: Communicable diseases are illnesses caused by pathogens (like bacteria, viruses, fungi, or protozoa) that can spread from an infected person, animal, or contaminated environment to a healthy individual. They are infectious and can be transmitted directly or indirectly. Nigerian
Example: Malaria (caused by Plasmodium parasites, transmitted by mosquito bites).
Commentary: This assesses understanding of the core definition and local relevance.
Question 2: Describe two different modes of transmission for malaria, explaining how each occurs.
Solution 2: Mode 1: Vector-borne Transmission: This is the primary mode. A female Anopheles mosquito, acting as a vector, bites an infected person, ingesting Plasmodium parasites. The parasites develop inside the mosquito, and when the infected mosquito later bites a healthy person, it injects the parasites into their bloodstream, causing infection.
Mode 2: Vehicle-borne Transmission (Less Common but possible): In rare cases, malaria can be transmitted through blood transfusions from an infected donor to a recipient, or via shared contaminated needles among drug users. This involves blood acting as a 'vehicle' for the pathogen.
Commentary: This checks the student's ability to differentiate transmission routes and apply them to a specific, highly relevant disease in Nigeria.
Question 3: Suggest three practical ways a family in a Nigerian home can prevent typhoid fever.
Solution 3: Ensuring Safe Drinking Water: Boiling all drinking water, using a water filter, or treating water with appropriate chemicals (e.g., PUR sachets) if the source is not treated public water.
Practicing Good Personal Hygiene: Washing hands thoroughly with soap and water before preparing food, before eating, and after using the toilet.
Maintaining Food Safety: Washing fruits and vegetables properly before consumption, cooking food thoroughly, protecting food from flies, and storing cooked food safely in covered containers.
Commentary: Focuses on actionable prevention strategies within a common household setting.
Question 4: Differentiate between communicable and non-communicable diseases, giving one example for each that is prevalent in Nigeria.
Solution 4: Communicable Diseases: These are infectious diseases caused by pathogens and can be transmitted from one person to another or from the environment/animals to humans.
Example (Nigeria): Cholera (caused by Vibrio cholerae bacteria, spread through contaminated water/food).
Non-Communicable Diseases: These are chronic conditions that are not infectious and cannot be transmitted from person to person. They often result from a combination of genetic, lifestyle, and environmental factors.
Example (Nigeria): Hypertension (High Blood Pressure), often linked to unhealthy diet, lack of exercise, and stress.
Commentary: This assesses the core distinction between the two disease categories with relevant Nigerian examples.
Community Health Initiatives: Students can apply their knowledge by actively participating in local community health initiatives. For instance, contributing to community clean-up exercises (e.g., drainage clearing to prevent mosquito breeding sites), promoting proper waste disposal in their neighborhoods, and advocating for safe water practices to combat diseases like malaria and cholera, which are prevalent in many Nigerian communities.
Personal and Family Health Decisions: The lesson empowers students to make informed choices regarding their own health and that of their families. This includes insisting on boiled or treated water, ensuring proper food hygiene at home, encouraging the use of insecticide-treated nets, practicing regular handwashing, and understanding the importance of routine immunizations for children. This directly impacts household health outcomes.
Economic and Social Impact Awareness: Understanding the burden of diseases in Nigeria allows students to appreciate the economic and social costs. For example, a malaria outbreak can lead to missed school days, reduced agricultural productivity, and high healthcare expenditure, thus affecting family income and national development. This fosters a sense of collective responsibility towards disease prevention and control for societal progress.