A vigorous immune system is vital to good health, both physical and mental. Chronic fatigue, endless colds, and symptoms of allergy are just some of the common manifestations of a weakened immune system, while there is increasing awareness of outright autoimmune disorders such a rheumatoid arthritis, lupus and Sjögren's syndrome.
Around 100,000 children in the UK suffer chronic illness, while some 20,000 families have a child unlikely to reach adulthood - figures reported to have doubled since the 1970s. Broken dreams and hearts are all-consuming facts of life for parents of a seriously ill child. Battling a combination of ongoing grief and exhaustion, parents also have to consider other children, grandparents and friends.