Health is the state of physical and mental well-being. Diseases, both communicable 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
Risk factors are linked to an increased rate of a disease. They can be: aspects of a person’s lifestyle,
substances in the person’s body or environment, effects of diet, smoking and exercise
Cancer: Diseases:
Is the result of changes in cells that lead to Diseases caused by viruses, bacteria, protists and fungi
uncontrolled growth and division. Benign are spread in animals and plants but this spread can be
tumours are growths of abnormal cells prevented
which are contained in one area, usually Pathogens are microorganisms that cause infectious
within a membrane. They do not invade disease. Pathogens may be viruses, bacteria, protists or
other parts of the body fungi. They may infect plants or animals and can be
Malignant tumour cells are cancers. They spread by direct contact, by water or by air. Bacteria and
invade neighbouring tissues and spread to viruses may reproduce rapidly inside the body. Bacteria
different parts of the body in the blood may produce poisons (toxins) that damage tissues and
where they form secondary tumours make us feel ill. Viruses live and reproduce inside cells,
causing cell damage
Viral:
Measles symptoms of fever and a red skin rash. Measles is a serious illness that can be fatal so most young
children are vaccinated against it. The measles virus is spread by inhalation of droplets from sneezes and coughs
HIV initially causes a flu-like illness. Unless successfully controlled with antiretroviral drugs the virus attacks the
body’s immune cells. Late stage HIV infection, or AIDS, occurs when the body's immune system becomes so badly
damaged it can no longer deal with other infections or cancers. HIV is spread by sexual contact or exchange of
body fluids such as blood which occurs when drug users share needles
Tobacco mosaic virus (TMV) is a widespread plant pathogen affecting many species of plants including tomatoes. It
gives a distinctive ‘mosaic’ pattern of discolouration on the leaves which affects the growth of the plant due to lack
of photosynthesis
Bacterial:
Salmonella food poisoning is spread by bacteria ingested in food, or on food prepared in unhygienic conditions. In
the UK, poultry are vaccinated against salmonella to control the spread. Fever, abdominal cramps, vomiting and
diarrhoea are caused by the bacteria and the toxins they secrete
Gonorrhoea is a sexually transmitted disease (STD) with symptoms of a thick yellow fluid secretion and pain on
urinating. It is caused by a bacterium and was easily treated with the antibiotic penicillin until many resistant
strains appeared. Gonorrhoea is spread by sexual contact. The spread can be controlled by treatment with
antibiotics or the use of a barrier method of contraception
Fungal:
Rose black spot is a fungal disease where purple or black spots develop on leaves, which often turn yellow and
drop early. It affects the growth of the plant as photosynthesis is reduced. It is spread in the environment by water
or wind. Rose black spot can be treated by using fungicides and/or removing and destroying the affected leaves
Protist:
The pathogens that cause malaria are protists. The malarial protist has a life cycle that includes the mosquito.
Malaria causes recurrent episodes of fever and can be fatal. The spread of malaria is controlled by preventing the
vectors, mosquitos, from breeding and by using mosquito nets to avoid being bitten