Allergies an epidemic to modern societies
Allergy literally means 'altered reaction'. Allergies cause the body to 'overreact' to what are normally harmless substances. Examples are house dust mite allergy, hay fever and food allergy. The immune system regards certain substances as intruders, against which it must 'arm' itself, resulting in a hypersensitivity reaction which can take various forms.
The first allergy report dates back to about 3,000 years BC. It would, however, take a few millennia before the first accurate description appeared. It was not until 1800 that an English doctor described hay fever as 'a summer cold'. Hay fever was not associated with other allergies until almost a century later. The last hundred years have showed an enormous increase in the number of people with allergic disorders.
The causes have not yet been specified. It is likely that our different lifestyle, industrialisation and other environmental factors play a role. The last century has also seen a tremendous increase in knowledge about allergy, enabling people to be treated more effectively.