15th July 2020




CLASS: Grade 4

DATE: 26th June, 2020

SUBJECT: Basic Science and Technology

TOPIC: Pathogens: communicable and Non-communicable diseases.

Reference: Stan Basic Science and Technology for primary 5

Brief explanation

Most diseases are caused by various organisms such as bacteria, viruses and a host of other disease-causing organisms. When one falls sick, his entire body is robbed of comfort and ease. If these condition is not properly managed or given immediate attention, it could result to permanent disability or death.

Notes for the pupils

Meaning of pathogens

Pathogens are disease-causing agents (organisms).

Types of pathogens

  1. Bacteria
  2. Fungi
  3. Virus
  4. Parasites

Meaning of disease

Diseases are any harmful change that affects the normal nature and function of the body.

Classification of diseases

  1. Communicable disease
  2. Non-communicable disease

Communicable diseases are those diseases that spread from one person to another, e.g. cough, measles, ringworm, chicken pox, small pox, HIV/AIDs etc.

Communicable diseases can be spread through the following modes:

  1. Air: e.g. Tuberculosis (TB), SARS (Severe Acute Respiratory Syndrome).
  2. Food and water: e.g. ringworm, cholera etc.
  3. Insect bites: malaria caused by female anopheles mosquitoes, sleeping sickness caused by tsetse flies.
  4. Body contacts: by sharing clothes or sleeping on the same bed with infected person e.g. measles, Ebola etc.
  5. Blood transfusion: e.g. HIV/AIDS.
  6. Cuts and wounds: e.g. Tetanus.

Zoonotic diseases are diseases of animals that can be contacted by humans e.g. Rabies, bird flu, Ebola etc.

Sexually Transmitted Diseases (STDs)

These are diseases that can be spread through sexual intercourse. They include:

  1. HIV (Human-Immune Virus)
  2. AIDS (Acquires Immuno-Deficiency Syndrome)
  3. Gonorrhoea

Non-communicable diseases

These are diseases that cannot be transmitted from one person to another. They may be because by the following:

  1. Heredity e.g. Sickle cell anaemia, asthma, epilepsy, diabetes etc.
  2. Malnutrition e.g. kwashiorkor, goitre, Scurvy etc.
  3. Poor life style: smoking of cigarettes leading to cancer of the lungs; drinking too much alcohol leading to liver damage; lack of exercise leading to overweight, obesity and heart related diseases such as hypertension and stroke.

Difference between sickness and illness

Sickness refers to a condition you experience when you do not feel well while illness is a disease affecting the body or the mind.

Difference between signs and symptoms

Sign is an outward manifestation of sickness that can be detected by someone other than the individual affected by the disease while symptoms is the internal feelings experienced by the individual affected by the diseases.


  1. Define the following

(a) pathogens

(b) Disease

(c) Zoonotic disease


  1. Differentiate the following

(a) Sickness and Illness

(b) Signs and Symptoms

(c) Communicable disease and Non-communicable disease.


  1. Write down the full meaning of the following

(a) STDs


(c) AIDs

(d) SARS

(e) TB