Books on allergy

What does the word allergy mean?

Is allergy inherited?

Environment & allergy

Is allergy increasing?

A good book on allergy is Essential Allergy, by Niels Mygind, Ronald Dahl, Soren Pedersen and Kristian Thestrup-Pedersen 2nd edition, published by Blackwell, ISBN: 0632036451, price: £29.50, year published: 1996.
It is intended for doctors, mainly specialists, but people who are not doctors may well find it a good source of information too.

There is also a shorter version. Title: Instant Allergy, by the same authors, intended for nonspecialist doctors. Like the larger book, you may well find this interesting if you are not medically qualified. We don't agree with everything it says, but doctors never do agree to that extent. It is a marvellous little book. Blackwell, ISBN 0 632 04232 X, Price £15.95.

There are many books on allergy written for lay people. Their reliability varies; many are full of ideas not taken seriously by doctors who are widely recognised allergy experts. One way of making it more likely that what you read will be useful is to use books written by doctors who work in recognised mainstream teaching hospitals.

Go to our web page on Other sources of information for other web pages related to allergy.

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We need immunity to protect us from infections, and without our immune systems we would soon die from infection. A very important group of infections throughout human history has been infection with parasites such as parasitic worms. Even today, when worm infections have almost been banished from developed countries, worm parasites cause vast numbers of deaths in poorer countries. But even when we have got rid of the worms from our surroundings we still have the same genes which protected us from this scourge. When we get allergies like hay fever or allergy to nuts, what happens is that this unused part of our immune systems is causing mischief.

There are other ways in which our immune systems can cause allergic diseases. For example if you are allergic to nickel in jewellery or clothing, this is caused by quite a different part of our immune system. But it is still 'immunity gone wrong'.

The word "allergy" means "altered working". It was coined at the beginning of the 20th century to describe the fact that dogs immunised with venom proteins from another animal had fatal reactions when they had another injection of that protein. Instead of being protected by immunisation; the dogs died during the "allergic reaction". In fact they had a kind of reaction for which the experimenters coined the word "anaphylaxis", meaning the opposite of "prophylaxis" or protection. Vaccination against bacteria and viruses produced protection, or "prophylaxis", but the experiments showed that immunisation could also produce increased harm on further contact, or "anaphylaxis".

Since then the word "allergy" has been used in two senses. Most people use it to mean an illness produced by a reaction of our immune system to some protein or other substance.

Examples are hayfever, allergic asthma, food allergy, drug allergy, and infantile eczema.

Scientists use the word "allergy" to mean any kind of altered state of the immune system in which it reacts differently to a substance as a result of previous contact. To refer to illnesses brought on in this way, they use the expression "allergic disease".

We will use the word "allergy" to mean "allergic disease", the way most people use it.

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What kinds of allergy are there?

The first kind is the common kind of allergy which causes hayfever, allergic asthma, food allergy, and some drug allergy. This type involves a very quick reaction, typically taking 15 minutes to become really obvious, and is called immediate hypersentitivity

The second is a peeling eczema-like rash called contact dermatitis, which some people get from metals such as nickel in jewellery, watches or clothing items. It can also be caused by cosmetics, sticking plaster, or a variety of other things which come into contact with the skin. This type of reaction is much slower, typically taking two days to become really obvious, and is called delayed hypersentitivity

These two groups of allergic illnesses are completely separate, and having one kind does not mean you are more likely to have the other kind.

We are only going to be dealing with allergies related to the first group, immediate hypersentitivity.

Illnesses commonly caused by immediate hypersensitivity are:

• Hayfever

• Infantile eczema and similar eczema later in life

• Asthma of the allergic type; most asthma, in fact.

• Food allergies

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Is allergy inherited?

This tendency is called atopy. If you have the tendency you are atopic. Atopy is the tendency to develop immediate hypersensitivity more readily than most people if substances capable of causing this kind of allergy come into contact with the surface membranes (so-called mucous membranes) of your digestive system or your respiratory system. Possibly this also applies to some things which come into contact with the skin.

It is obviously possible to inherit more than one such gene, and some atopic people are more atopic than others. If you are more atopic you are likely to become allergic to a lot of things. If you are only slightly atopic you are likely to become allergic to only a few.

It makes no sense whatever to avoid having children because you have allergy genes. A third of the human race has these genes, so there will always be untold numbers of people with these genes about, whatever you do. What is more, we know that even if you have the genes, it still depends on our environment whether allergies develop. People with these same genes did not have so many troublesome allergies in the past, and we expect that in the future we'll know why and will be able to stop allergies from happening. If you have a terrible form of allergy, it is very unlikely that your children will have such bad allergies; so much depends on other things. So many other things are more important than whether you have allergy that your decision to have children should not be influenced at all by allergy.

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What about the environment?

• Air pollution has been blamed for increased hayfever in Japan, and may have played a part in causing hayfever in other countries.

• The month in which you are born makes a slight difference to your chance of getting hayfever. It seems that if you are exposed to things which cause allergy in the first three to six months of life, you are more likely to be allergic to them later in life. In other words, there is a 'vulnerable period' in early childhood. This has given rise to the idea of allergy prevention by avoiding early contact with things which cause allergy.

• Surprisingly, your chance of having infantile eczema, hayfever, or positive allergy skin test results goes down if you have more older brothers and sisters.Why? Well, it seems that people with more brothers and sisters when they are little get more infections at that age, and make lots of antibody to bacteria and viruses. When our immune system gears itself up to make lots of the common type of antibody against germs, it can't make lots of allergy antibodies at the same time.

  Scientists are looking at the possibility of boosting the kind of antibody response we make against germs in order to protect children against allergies later in life.

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Is allergy increasing?

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Why should allergies be increasing? One piece of evidence comes from a report that a person's chance of having hayfever is higher if he or she has few or no brothers or sisters, and lower if more brothers or sisters. D. Strachan, who reported this in 1989, thought an explanation for this might be that children with more brothers or sisters have more infections in childhood, and that the infections might protect against allergy. Subsequent immunological research has provided an explanation for this.

Air pollution from road traffic has been blamed. The main evidence for this has come from Japan, where 'hayfever' due to the pollen of the Japanese cedar tree has increased dramatically since the second World War. The increase seemed prominent particularly where there was diesel traffic rather than where the cedar trees grew. Experiments showed that mice produced the allergy-causing antibodies much more readily if particles from diesel exhaust fumes were put into the nose. However, attempts to confirm the effect of traffic fumes on nasal allergy in Europe have run into difficulties. The evidence for a link between asthma and air pollution is weaker still, though a lot of research is going on and some of this has provided evidence that air pollutants can, in the laboratory, produce changes which would be expected to worsen asthma.

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