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RTDinfo  01/03/01    

Title   Elusive allergies

Nearly one in three Europeans suffers - or will suffer - from an allergy. 10% of children suffer from asthma. Described by some scientists as 'the real millennium bug', allergies have become progressively more common over the past two decades. And the social cost - in terms of health care and absenteeism, for example - is estimated at 45 billion euros a year. A major research effort is essential in this field where our knowledge shows some surprising gaps.

First described by the Austrian physician Clemens von Picquet back in 1906, an allergy is an 'inflammation' which follows exposure to a specific substance or micro-organism, known as an allergen. The body responds to a usually inoffensive stimulus by triggering the action of immune mechanisms - just as it does when defending us against germs, but in this case for no real purpose. The body's reaction is violent and, in the extreme and rare cases of anaphylactic shock, can even prove fatal.

'There are many different types of cause,' explains Dr Alain Vanvossel, a scientific officer at the Research DG. 'Genetic factors and immunological aspects can all play a part, as well as pollution and other environmental factors, as can lifestyle, including diet. So all these avenues must be explored if we want to make any progress in preventing allergies.'

Allergies are made all the more complex by the fact that they are often triggered by a combination of factors which are difficult to identify. Their incidence can vary in the course of a lifetime and the phenomenon of crossed reactivity further complicates an already difficult diagnosis.

Increase in asthma

Respiratory allergies are among the most common. They include allergic rhinitis, such as the familiar hay fever, the incidence of which seems to have increased from 1% of the population at the beginning of the 20th century to between 15% and 20% over recent years, affecting adolescents and young adults in particular. 'This complaint should not be viewed as a minor irritation,' states the European Allergy White Paper. (1) 'Recent studies show that chronic allergic rhinitis, usually caused by the allergens found in buildings, cause a level of discomfort in the patient equivalent to that of moderate asthma. Some studies even suggest that this complaint can lead to asthma.'

The link is worrying, as asthma is another major allergy. It affects 10% of children, continues in 5% of adults and affects twice as many people as 20 years ago. Polluted air - with NOx from vehicle emissions, for example - is increasingly being cited as the cause of the problem and some statistics show that asthma is more common in urban than rural areas. Socio-economic factors are also mentioned, as asthma is more frequent among the socially disadvantaged. Although the resulting mortality is low in Europe, the number of children who suffer from it is a cause for concern, as is the number of determining factors which remain unidentified and which are probably linked to the interaction between our genes and lifestyle.

Skin allergies

Skin allergies are another major category of allergy. A number of studies have found a worrying increase in atopic dermatitis over recent decades. Also linked to hereditary factors, in some regions of Europe as much as a quarter of the population is believed to be affected by this condition. Eczema and urticaria are also affecting a growing number of people, with experts predicting that between 40% and 60% of them are at risk of going on to develop respiratory problems.

Diet is very often seen as being responsible for these disorders. Here it is more a question of intolerance than of allergies proper as the symptoms are not due to an activation of the immune mechanism. But whatever the case, this hypersensitivity is also linked to a change in lifestyle.

Targeted research

'Europe is certainly not without its strengths in conducting the research required to combat this public health problem,' believes Dr Vanvossel. 'In addition to multidisciplinary teams of high-level scientists, it also has the diversity of populations, lifestyles, environments and public-health systems to permit a very targeted approach.'

The Quality of life and management of human resources programme under the Fifth Framework Programme for Research is already supporting studies by over 50 European teams, many of them also cooperating with laboratories in EU-applicant countries (see examples below). Some are concerned specifically with asthma and the aetiology of allergies, some with food allergens, and some with methods of diagnosis and treatment strategies. 'The emphasis is clearly on prevention. That is why it is important to ensure that the results get back to the people in question, and that they are put to the best possible use, as it is often issues of lifestyle which are raised by these diseases,' concludes Dr Vanvossel. Further calls for proposals for research on allergies are planned for March 2001 and 2002 under the Quality of life programme. These will make it possible to finance a large number of innovative projects in this field.

(1) European Allergy White Paper - Allergic diseases as a public health problem in Europe, The UCB Institute of Allergy, 1997
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Breathing in Europe

The ECRHS II (European Community Respiratory Health Survey) project is an ambitious study following on from an initial survey carried out in 1992-93. More than 10 000 young adults from 14 European countries will once again come under the scrutiny of scientists and doctors from 29 scientific centres. The aim is to determine the factors linked to the incidence (or remission) of allergic sensitivity and asthma, and to reduction in the pulmonary function. The ECRHS II project will compile an extensive database with multiple variables on respiratory allergies - especially asthma - and risk factors (environmental, hereditary, etc.).

'We are also going to compile a blood bank for the purposes of DNA analysis,' explains Dr. Deborah Jarvis, the study co-ordinator. 'It will be possible to correlate these results with every type of incidence recorded. That will enable us to explore the associations between exposure and response at a really pertinent European level.'


Dr. Deborah Jarvis
Kings College London (UK) 

Intestinal flora

The inquiry into intestinal flora is particularly innovative in that it is exploring the quite paradoxical association found by most epidemiological studies between a high risk of allergy and a Western upbringing under hygienic conditions. 'We found that children from small, well-to-do families, with sanitary housing, are at greater risk of developing allergies,' explains Agnes Wold of Gothenburg University (SE), co-ordinator of the Allergyflora (Impact of intestinal microflora on allergy development) project. 'Sanitary conditions in Europe are totally different from those of 100 years ago, a time when allergies were virtually unknown.'

The hypothesis? The microflora of the intestine, the first system to be colonised by micro-organisms after birth, play a key role in regulating the immune system. The researchers believe that our children's microflora inhibit the development of tolerance to the antigens present in the digestive system. Three hundred babies living in Sweden, the United Kingdom and Italy will be monitored from birth, to enable scientists to confirm - or qualify - this position. The project's ultimate objective is to open up new avenues for prevention.


Agnes Wold
Université de Göteborg (SE) 

Monitored pregnancies

The exposure of expectant mothers to certain pollutants could make their babies more prone to develop allergies. This is the hypothesis being studied by researchers on the Plutocracy project (Placental uptake and transfer of environmental chemicals relating to allergy in childhood years). 'Placental contamination by pollutants in general, and PCBs and heavy metals in particular, could affect certain functions of the placenta - and thus the development of the fœtus,' explains Dr. Margaret Saunders, the project coordinator. 'We are looking for the link between the mother's exposure, the contamination of the placenta and the epidemiology of allergies in children.' This research is particularly important in seeking to reduce risks to children's health, starting in the womb.


Dr. Margaret Saunders
University of Bristol (UK)

Country life
Is a lack of contact with germs from a very early age damaging to health? Does excessive hygiene lead to immune deficiency and risks of allergy? It seems that children in frequent contact with animals - on farms, for example - are less prone to allergies. The same is true of those brought up according to the principles of anthroposophy (1) who, among other things, receive fewer vaccines and antibiotics, and enjoy a diet that is richer in fermented products. But why? That is what the researchers on the Parsifal project (Prevention of allergy. Risk factors for sensitisation in children related to farming and anthroposophic life style) aim to find out. By exploring a number of avenues (diet, vaccinations, infections, contacts with animals, microbial contaminants, intestinal microflora, etc.), this study should help develop a prevention policy for allergies.

(1) Anthroposophy, a doctrine developed by the Austrian philosopher Rudolf Steiner (1861-1925), advocates a harmonisation between the physical and the spiritual state, between man and the universe.


Göran Pershagen
Karolinska Institute of Environmental Medicine, Stockholm (SE)

Children and pollution

The Airallerg project (Effects of outdoor and indoor air pollution on the development of allergic disease in children) is focusing on one of the prime suspects behind the increase in allergies: air pollution. Several hundred children in Sweden, Germany and the Netherlands are being monitored from birth. The researchers collect continuous information on the allergic sensitivity of the children and on the atmospheric pollutants to which they are exposed, both outdoors (such as the gases and particles emitted by vehicles) and indoors (mould, bacteria, tobacco, combustion gases from boilers and cookers, etc.).

'The aim is two-fold,' stresses project co-ordinator Professor Bert Brunekreef. 'First, we are seeking to establish associations between exposure to these substances from the very earliest age and the frequency of allergies in these same children at the age of four. We will then seek to identify interactions between exposure to certain specific chemical or biological substances and the frequency of sensitisation to common allergens and of allergies among children at the age of four.' This study will make it possible to shed light on the relative importance of a number of risk factors to which Europe's youngest inhabitants are exposed.


Bert Brunekreef
University of Utrecht (NL)