What are the main types of diseases studied in the IB MYP Science curriculum?

In the IB MYP Science curriculum, diseases are generally categorized into infectious and non-infectious diseases. Infectious diseases are caused by pathogens such as bacteria, viruses, fungi, and parasites, while non-infectious diseases are often related to genetics, lifestyle, or environmental factors, such as diabetes, cancer, and heart disease.

How do infectious diseases spread among humans?

Infectious diseases can spread through various means, including direct contact with an infected person, indirect contact via surfaces, airborne transmission through droplets, vector-borne transmission by insects, and through contaminated food or water. Understanding these transmission methods is crucial for preventing the spread of diseases.

What role do vaccines play in controlling diseases?

Vaccines are crucial in controlling infectious diseases by preparing the immune system to recognize and combat pathogens. They work by introducing a harmless component of the pathogen, prompting the body to produce antibodies. This process helps prevent future infections and can lead to herd immunity, protecting those who cannot be vaccinated.

What are some common non-infectious diseases and their risk factors?

Common non-infectious diseases include cardiovascular diseases, diabetes, cancer, and respiratory diseases. Risk factors for these diseases often include lifestyle choices such as poor diet, lack of exercise, smoking, and excessive alcohol consumption, as well as genetic predispositions and environmental exposures.

How can lifestyle changes help in the prevention of non-infectious diseases?

Lifestyle changes play a significant role in preventing non-infectious diseases. Adopting a balanced diet, engaging in regular physical activity, avoiding tobacco and excessive alcohol, and managing stress can significantly reduce the risk of developing conditions like heart disease, diabetes, and certain types of cancer. These changes promote overall health and well-being.

Why is "Using antibiotics for a cold." a common mistake in Diseases?

Why it happens: Both feel like 'infections'. How to avoid it: Antibiotics only kill BACTERIA. Colds and flu are VIRAL — antibiotics do nothing. Overuse breeds antibiotic-resistant bacteria.

Why is "Calling cancer 'contagious'." a common mistake in Diseases?

Why it happens: It can run in families. How to avoid it: Most cancers are NON-communicable. Some are linked to viral infections (e.g. HPV → cervical cancer), but the cancer itself doesn't spread between people.

Human HealthIB MYP Sciences (Years 1-5)

Diseases

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Diseases — IB MYP Sciences: communicable, non-communicable, pathogens and transmission

Disease is anything that disrupts the normal functioning of the body. This MYP Sciences note covers the difference between communicable and non-communicable diseases, the four types of pathogen, how infections spread, and what you can do to stop them.

What you’ll learn

Mapped to the IB MYP Sciences subject guide (2026 onwards).

MYP Sciences A — Distinguish communicable from non-communicable diseases.
MYP Sciences A — Name and identify the four types of pathogen.
MYP Sciences A — Describe the main routes of disease transmission.
MYP Sciences D — Evaluate a prevention strategy in a real-world context.

Two big categories of disease

Communicable (catch from others) vs non-communicable (you develop them).

Communicable diseases are caused by pathogens — microorganisms or viruses that invade the body and multiply. They CAN spread from one person to another.

Examples: colds, flu, COVID-19, tuberculosis, malaria, athlete's foot.

Pathogens come in FOUR main groups:

Type	Examples	Treatment
Bacteria	strep throat, TB, food poisoning	Antibiotics
Viruses	cold, flu, COVID-19, measles, HIV	Antivirals (some) + vaccines
Fungi	athlete's foot, ringworm, thrush	Antifungals
Protoctists	malaria, sleeping sickness	Specific drugs (e.g. antimalarials)

Non-communicable diseases are NOT caused by pathogens and don't spread between people. They develop over time, often related to genetics + lifestyle + environment.

Examples: heart disease, type 2 diabetes, most cancers, asthma, mental illness, Alzheimer's.

Today, non-communicable diseases are the LEADING CAUSE of death globally (about 70%) — partly because we've made enormous progress against communicable ones (clean water, vaccines, antibiotics).

Communicable: caused by a pathogen; spreads person-to-person.
Non-communicable: develops without infection; can't spread.
Four pathogen groups: bacteria, viruses, fungi, protoctists.

How communicable diseases spread

Air, water, food, contact, fluids, vectors.

Pathogens transmit by various routes — knowing them lets you BREAK the chain.

Airborne (droplets and aerosols): cough or sneeze releases droplets carrying viruses or bacteria. Examples: cold, flu, COVID-19, TB. Prevention: hand washing, masks, ventilation, isolation when sick.

Water-borne: drinking contaminated water. Examples: cholera, typhoid, dysentery. Prevention: treated drinking water, sanitation, boiling water.

Food-borne: eating contaminated or improperly stored food. Examples: salmonella, E. coli food poisoning. Prevention: refrigeration, thorough cooking, hand washing during food prep.

Direct contact: touching infected skin or surfaces. Examples: athlete's foot, ringworm, MRSA. Prevention: hand washing, not sharing towels, cleaning surfaces.

Body fluids: blood, sexual fluids. Examples: HIV, hepatitis B and C. Prevention: condoms, sterile needles, blood screening.

Animal vectors: an animal carries the pathogen and transmits to humans. Mosquitoes carry malaria (a protoctist); ticks carry Lyme disease (bacterial). Prevention: insect repellent, mosquito nets, draining standing water.

PUBLIC HEALTH measures combine many of these — e.g. the eradication of smallpox involved global vaccination (1967-1980). Vaccination is one of the most cost-effective public-health interventions ever invented.

Routes: airborne, water-borne, food-borne, direct contact, body fluids, vectors.
Each route has prevention strategies.
Vaccination is among the cheapest, most effective public health tools.

How it’s examined

Criterion A tests definitions and pathogen recognition. Criterion D often asks for evaluation of public-health responses.

Sources: IB MYP Sciences guide (IBO, official subject guide); WHO Disease Fact Sheets (publicly available). Last reviewed 2026-05-25.

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Step-by-step worked examples — Diseases

Step-by-step solutions to past-paper-style questions on diseases, written exactly the way a tutor would explain them at the board.

1Communicable or not?
Getting started• classification
Question
Classify each: (a) influenza, (b) diabetes type 2, (c) malaria, (d) heart disease.
Step-by-step solution
1. Step 1
  (a) Influenza — virus, spreads via droplets → COMMUNICABLE.
2. Step 2
  (b) Diabetes type 2 — diet/genetics → NON-COMMUNICABLE.
3. Step 3
  (c) Malaria — protoctist spread by mosquitoes → COMMUNICABLE.
4. Step 4
  (d) Heart disease — lifestyle/genetics → NON-COMMUNICABLE.
Answer
(a) communicable, (b) non-communicable, (c) communicable, (d) non-communicable.
2Match pathogen type
Building confidence• pathogens
Question
Identify the pathogen type for: (a) athlete's foot, (b) COVID-19, (c) salmonella food poisoning, (d) malaria.
Step-by-step solution
1. Step 1
  (a) athlete's foot — FUNGUS.
2. Step 2
  (b) COVID-19 — VIRUS.
3. Step 3
  (c) salmonella — BACTERIA.
4. Step 4
  (d) malaria — PROTOCTIST (carried by mosquitoes).
Answer
(a) fungus, (b) virus, (c) bacterium, (d) protoctist.
3Choosing a prevention strategy
Stretch• prevention
Question
A village suffers from frequent cholera outbreaks. Suggest TWO complementary strategies to prevent further outbreaks and explain why each works.
Step-by-step solution
1. Step 1
  (i) Provide CLEAN DRINKING WATER (treated or boiled) — cholera is water-borne, so removing contamination at the source breaks the transmission chain.
2. Step 2
  (ii) Improve SANITATION — proper toilets prevent faecal contamination of water supplies.
3. Step 3
  Both together attack the SOURCE and PATHWAY of transmission. Vaccination would help too but the water-and-sanitation approach is more durable.
Answer
Clean drinking water + proper sanitation: removes contamination and prevents new contamination, breaking the cholera transmission chain.

Key Definitions and Keywords — Diseases

Definitions to memorise and the exact keywords mark schemes credit for diseases answers — sharpened from recent examiner reports for the 2026 IB MYP Sciences sitting.

Pathogen
Examiner keyword
A microorganism or virus that causes disease.
Communicable disease
Examiner keyword
An illness caused by a pathogen that can pass from person to person.
Non-communicable disease
Examiner keyword
An illness that develops over time (often genetic + lifestyle) and doesn't transmit.
Vector
Examiner keyword
An animal that carries a pathogen and transmits it to other organisms (e.g. mosquitoes carry malaria).

Common Mistakes and Misconceptions — Diseases

The traps other students keep falling into on diseases questions — taken from recent IB MYP Sciences examiner reports and mark schemes — and how to avoid them.

✕Using antibiotics for a cold.
Why it happens
Both feel like 'infections'.
How to avoid it
Antibiotics only kill BACTERIA. Colds and flu are VIRAL — antibiotics do nothing. Overuse breeds antibiotic-resistant bacteria.
✕Calling cancer 'contagious'.
Why it happens
It can run in families.
How to avoid it
Most cancers are NON-communicable. Some are linked to viral infections (e.g. HPV → cervical cancer), but the cancer itself doesn't spread between people.

Practice questions

Exam-style questions with step-by-step worked solutions. Try one before checking the method.

Past paper style quiz

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Diseases — frequently asked questions

The things students keep getting wrong in this sub-topic, answered.

Type

Examples

Treatment

Bacteria

strep throat, TB, food poisoning

Antibiotics

Viruses

cold, flu, COVID-19, measles, HIV

Antivirals (some) + vaccines

Fungi

athlete's foot, ringworm, thrush

Antifungals

Protoctists

malaria, sleeping sickness

Specific drugs (e.g. antimalarials)

Pathogens transmit by various routes — knowing them lets you BREAK the chain.

Water-borne: drinking contaminated water. Examples: cholera, typhoid, dysentery. Prevention: treated drinking water, sanitation, boiling water.

Food-borne: eating contaminated or improperly stored food. Examples: salmonella, E. coli food poisoning. Prevention: refrigeration, thorough cooking, hand washing during food prep.

Direct contact: touching infected skin or surfaces. Examples: athlete's foot, ringworm, MRSA. Prevention: hand washing, not sharing towels, cleaning surfaces.

Body fluids: blood, sexual fluids. Examples: HIV, hepatitis B and C. Prevention: condoms, sterile needles, blood screening.

Diseases

Short Study Notes in the form of Slides

Short Study Notes — Diseases

Detailed Notes

What you’ll learn

How it’s examined

1Communicable or not?

2Match pathogen type

3Choosing a prevention strategy

Pathogen

Communicable disease

Non-communicable disease

Vector

✕Using antibiotics for a cold.

✕Calling cancer 'contagious'.

Practice questions

Past paper style quiz

Assess your understanding

Diseases — frequently asked questions

Diseases

Short Study Notes in the form of Slides

Short Study Notes — Diseases

Detailed Notes

What you’ll learn

How it’s examined

1Communicable or not?

2Match pathogen type

3Choosing a prevention strategy

Pathogen

Communicable disease

Non-communicable disease

Vector

✕Using antibiotics for a cold.

✕Calling cancer 'contagious'.

Practice questions

Past paper style quiz

Assess your understanding

Diseases — frequently asked questions