Health issues: Diseases, both communicable Communicable diseases (page 35) and non-communicable, are major causes of ill health. Other factors including diet, stress and life situations may have a profound effect on both physical and mental health.

The idea

Ill health has many causes. Communicable diseases are spread between organisms by pathogens such as bacteria and viruses, for example influenza or malaria. Non-communicable diseases are not passed between people and include cancer, type 2 diabetes and coronary heart disease. Both types are major causes of ill health worldwide. Other factors also have a profound effect. A poor diet lacking vitamins can cause deficiency disease, while excess energy intake contributes to obesity and type 2 diabetes. Long-term stress is linked to raised blood pressure and poorer mental health. Life situations such as poor housing, low income, pollution or limited access to healthcare increase the risk of ill health. These factors often interact: stress may lead to poor diet, and poor diet may worsen stress, so effects on physical and mental health are linked.

What earns the marks

• Communicable diseases are caused by pathogens and can be spread between organisms, for example influenza and malaria.
• Non-communicable diseases are not transmitted between people and include cancer, type 2 diabetes and coronary heart disease.
• Diet can cause ill health, for example deficiency diseases from missing nutrients or obesity and type 2 diabetes from excess energy intake.
• Stress and life situations such as poor housing, low income or pollution can profoundly affect physical and mental health.
• Risk factors often interact, so one factor can increase the effect of another on health.

Common mistakes and how to put them right

• Calling all diseases communicable.

  Put it right: Non-communicable diseases such as cancer are not spread between people.

• Assuming a risk factor directly causes a disease.

  Put it right: A risk factor increases the chance of ill health but does not guarantee it.

• Listing factors without linking them to physical or mental effects.

  Put it right: State the effect, for example stress raising blood pressure or poor diet causing deficiency disease.

Exam tips

• Classify each disease in a question as communicable or non-communicable before explaining its effect.
• Link every risk factor to a specific physical or mental health outcome rather than leaving it as a list.
• Use connectives such as 'which increases the risk of' to show cause and effect clearly.