Diseases — Common Communicable and Non-Communicable Diseases
Overview
Diseases form a critical component of Environmental Studies for KTET Category I, connecting health education with everyday life experiences of primary-level learners. This topic bridges science concepts with practical awareness about personal hygiene, community health, and disease prevention—making it highly relevant for classroom teaching.
For KTET, expect questions testing your knowledge of disease classification, transmission modes, causative agents, symptoms, and prevention methods. The exam frequently asks about diseases common in Kerala's tropical climate (dengue, malaria, leptospirosis) alongside nationally relevant conditions. Understanding how to teach young children about diseases using age-appropriate methods is equally important, as pedagogy questions often accompany content questions.
Mastering this topic requires memorising key facts about specific diseases while understanding broader concepts of how diseases spread and how communities can prevent them through collective action.
Key Concepts
- Communicable diseases spread from one person to another through direct contact, air, water, food, or vectors (insects/animals). Also called infectious or contagious diseases.
- Non-communicable diseases (NCDs) do not spread from person to person. They result from genetic factors, lifestyle choices, or environmental conditions. Also called chronic diseases.
- Pathogens are disease-causing microorganisms—bacteria, viruses, fungi, protozoa, and worms. Each pathogen type responds to different treatments.
- Vectors are organisms that transmit pathogens without getting sick themselves. Mosquitoes, houseflies, rats, and dogs are common vectors in the Indian context.
- Incubation period is the time between infection and appearance of symptoms. Different for each disease and important for understanding disease spread.
- Immunity is the body's ability to resist infection. Can be natural (after recovering from disease) or artificial (through vaccination).
- Endemic diseases are constantly present in a region. Malaria in parts of Kerala is endemic. Epidemic refers to sudden widespread outbreak in a community.
Formulas / Key Facts
| Disease | Type | Caused By | Spread Through | Key Symptoms | Prevention |
|---|---|---|---|---|---|
| Malaria | Communicable | Plasmodium (protozoa) | Female Anopheles mosquito | High fever with chills, sweating, headache | Mosquito nets, repellents, no stagnant water |
| Dengue | Communicable | Dengue virus | Aedes aegypti mosquito | High fever, severe joint/muscle pain, rash | Eliminate breeding sites, wear full-sleeved clothes |
| Typhoid | Communicable | Salmonella typhi (bacteria) | Contaminated water/food | Prolonged fever, weakness, stomach pain | Safe drinking water, proper sanitation, Typhoid vaccine |
| Cholera | Communicable | Vibrio cholerae (bacteria) | Contaminated water/food | Severe watery diarrhoea, dehydration | Clean water, ORS for treatment, hygiene |
| Tuberculosis (TB) | Communicable | Mycobacterium tuberculosis | Airborne droplets | Persistent cough, weight loss, night sweats | BCG vaccine, covering mouth while coughing |
| COVID-19 | Communicable | SARS-CoV-2 virus | Respiratory droplets, aerosols | Fever, cough, breathing difficulty | Masks, hand washing, vaccination |
| Leptospirosis | Communicable | Leptospira bacteria | Contact with infected animal urine in water | Fever, muscle pain, jaundice | Avoid wading in floodwater, protective footwear |
| Diabetes | Non-communicable | Insulin deficiency/resistance | Not spread—lifestyle/genetic | Frequent urination, thirst, fatigue | Healthy diet, exercise, weight control |
| Hypertension | Non-communicable | Multiple factors | Not spread—lifestyle/genetic | Often no symptoms (silent killer) | Reduce salt, exercise, stress management |
| Cancer | Non-communicable | Abnormal cell growth | Not spread—genetic/environmental | Varies by type | Avoid tobacco, healthy lifestyle, screening |
| Asthma | Non-communicable | Airway inflammation | Not spread—allergic/environmental | Wheezing, breathlessness, chest tightness | Avoid triggers, use inhalers |
Kerala-Specific Points:
- Leptospirosis increases during monsoon floods
- Nipah virus outbreak (2018, 2021) spread through fruit bats
- High diabetes prevalence in Kerala compared to national average
Worked Examples
Example 1: Identifying Disease Type
Question: Raju has been suffering from high fever with severe body pain for three days. There are many cases of similar illness in his neighbourhood after recent heavy rains. Which disease is this likely to be, and what precautions should the community take?
Solution:
- Step 1: Identify pattern—fever with body pain after rains, many cases together
- Step 2: Post-monsoon conditions + mosquito breeding = likely dengue or chikungunya
- Step 3: Community precautions: Empty water from coolers, pots, tyres; use mosquito nets; spray insecticides; wear protective clothing
- Answer: Likely dengue fever. Community should eliminate mosquito breeding sites and use personal protection.
Example 2: Classifying Diseases
Question: Classify the following as communicable or non-communicable: (a) Jaundice (b) Heart disease (c) Measles (d) Arthritis
Solution:
- Jaundice — Communicable (caused by Hepatitis virus, spread through contaminated water)
- Heart disease — Non-communicable (lifestyle and genetic factors)
- Measles — Communicable (viral, spread through air)
- Arthritis — Non-communicable (joint inflammation, not infectious)
Example 3: Prevention Method
Question: Why is ORS given during diarrhoea instead of stopping the diarrhoea immediately?
Solution:
- Diarrhoea causes loss of water and salts from body
- ORS (Oral Rehydration Solution) replaces lost fluids and electrolytes
- Stopping diarrhoea immediately may trap pathogens inside
- ORS prevents dehydration, which is the main danger in diarrhoea
- Answer: ORS prevents life-threatening dehydration while the body naturally expels pathogens.
Common Mistakes
- Confusing vectors with pathogens → Mosquito is the vector; Plasmodium is the pathogen causing malaria. Vectors carry disease but don't cause it directly.
- Assuming all fevers are the same disease → Different diseases cause different fever patterns. Malaria has intermittent fever with chills; dengue has continuous high fever with body pain; typhoid has step-ladder pattern fever.
- Thinking non-communicable means not serious → NCDs like diabetes, cancer, and heart disease cause more deaths globally than communicable diseases. "Non-communicable" only means they don't spread person-to-person.
- Believing antibiotics work on all diseases → Antibiotics kill bacteria only. They do NOT work against viral diseases like dengue, COVID-19, or common cold. This is a frequently tested concept.
- Forgetting that some diseases have vaccines while others don't → Vaccines exist for typhoid, TB (BCG), measles, COVID-19. No vaccine currently for malaria, dengue, or common cold. Know which is which.
Quick Reference
- Water-borne diseases: Cholera, Typhoid, Jaundice, Dysentery — all prevented by clean drinking water
- Mosquito-borne diseases in Kerala: Malaria (Anopheles), Dengue (Aedes), Chikungunya (Aedes)
- Airborne diseases: TB, COVID-19, Measles, Common cold — prevented by masks and ventilation
- ORS formula: 6 teaspoons sugar + ½ teaspoon salt in 1 litre boiled/clean water
- Three Ds of NCD prevention: Diet, Discipline (exercise), Don't smoke/drink
- KTET tip: Remember the disease-vector-prevention chain—questions often test one element when given the other two