- Health is the state of physical and mental well-being; lots of factors affect the health of an individual
- Diseases, both communicable and non-communicable, are major causes of ill health; ill-health affects not only the sufferer but their family members and the contribution that individual can make to society
- Ill health can lead to a poorer quality of life or reduced lifespan
- The cost of an individual being ill – individuals who are sick may not be able to work and may require expensive healthcare (with the cost being attributed to the individual or a healthcare provider such as the NHS in the UK)
- Communicable diseases are caused by microorganisms called pathogens which can spread between individuals or individuals and animals
- eg. chickenpox, a common childhood disease, is caused by a viral pathogen called the varicella-zoster virus whereas Covid-19 is caused by the SARS-CoV-2 virus
- Non-communicable diseases are not caused by pathogens and their effects on health tend to be longer-lasting; examples are asthma, CHD and most cancers
- Factors including diet, stress and life situations may have a profound effect on both physical and mental health
- Eating a balanced diet that provides the right amount of energy and nutrients helps maintain good health whereas a poor diet can lead to deficiencies, obesity, diabetes and poor mental health
- Constantly being under stress can lead to cardiovascular issues (such as high blood pressure, increasing the risk of CHD) and poor mental health
- Where a person lives and their income can have a profound impact on health – this affects the standard of healthcare that is accessible to them (and what they can afford), what food they buy etc.
- Different types of disease may interact in ways that negatively affect the health of the individual
- Defects in the immune system mean that an individual is more likely to suffer from infectious diseases; individuals infected with HIV eventually end up with reduced numbers of lymphocytes circulating around the body which reduces the ability of the immune system to fight opportunistic infections like pneumonia
- Viruses living in cells can be the trigger for cancers; the HPV virus can infect cells of the cervix in women resulting in cervical cancer developing in some cases, whereas some strains of the hepatitis virus can cause liver cancer
- Immune reactions initially caused by a pathogen can trigger allergies such as skin rashes and asthma – these often develop as a result of an overactive immune response
- Severe physical ill health can lead to depression and other mental illness; both can negatively impact the immune system and lifestyle choices made by the individual, further compounding the effects of poor health
You should be able to translate disease incidence information between graphical and numerical forms, construct and interpret frequency tables and diagrams, bar charts and histograms, and use a scatter diagram to identify a correlation between two variables.
You should understand the principles of sampling as applied to scientific data, including epidemiological data.