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Farm residents with livestock, except poultry, have protection against allergy later in life

Michelle Lasley | Environmental Science & Resources 428, Professor Alan Yeakley

Abstract

There has been a worldwide increase in asthma and allergies over the last half-century. Many studies link this to the Western lifestyle and increased standard of living. In addition, the rise of atopic diseases has been linked to the decline of infectious disease. Furthermore, several studies have linked the use of antibiotics in infancy and early childhood to the prevalence of asthma, eczema, and allergy rhinitis. The post-industrial period saw changes in the development of allergies, increased risk of asthma and allergy rhinitis, or hay fever.

To discuss why these changes are happening, numerous European studies have linked less likelihood to experience allergies if children have parents who are farmers and more specifically children who live on farms in the presence of animals. These children, who live on farms with animals, have decreased adult asthma, allergy rhinitis, and eczema. A New Zealand study found that this was null when children were on farms with poultry. This is important because pediatricians find asthma and allergies, during the late 1970s, to be difficult to treat. Farm environment for children protects against allergic rhinitis and asthma. Exposure to environmental mycobacteria and actinomycetes could be the explanation. If planners could incorporate these findings in urban designs, perhaps symptoms of allergies in children would decrease, increasing the quality of life for all.

Introduction

Society’s quick change from an agrarian society to an industrial society has had many unforeseen affects on the urban landscape, or in the urban ecology. One such unforeseen affect is in allergies. Prior to the Industrial Revolution, there were few documented cases of hay fever, asthma, and other allergies. Victims of allergies can tell you that allergies have a debilitating affect on the sufferer. Because allergies affect every facet of the sufferer’s life, allergy has a direct correlation to Quality of Life (QOL) issues and measurements. As QOL decreases, the potential to treat allergies gets harder.1 Treating allergies and the occurrence of allergies has startling costs to society. Additionally, allergy is so prevalent that new professions have arisen out from this increase and formation of allergy.

With such a wide-ranging affect, it is helpful to know what is included in allergy. Recent papers include in allergies the following types: allergy rhinitis (hay fever), asthma (inflammation of the bronchial tubes), and atopic/eczema/dermatitis syndrome (AEDS) (skin rashes and conditions).2 Several studies over the past two decades indicate a strong correlation between protection against allergies in adulthood and exposure to farm animals, except poultry, as a child. This paper will show the debilitating affect allergy has on young people, a basic introduction on what happens in allergy sufferers; a discussion of the studies showing links between livestock and allergy protection; a discussion of the studies that show an adverse link, especially in regards to poultry; and finally a summary of what was shown with suggestions on where studies should next proceed.

Allergy – Symptoms & Basic History

For one hundred years now, modern science has known that synthetic antihistamine would protect an animal from induced anaphylaxis, meaning that for one hundred years we have known what allergies look like and a basic idea of how to control allergies. Then, about 65 years ago, immunoglobulin E (IgE) was discovered as the acting carrier of ragweed, and later other allergens, the main component whose sensitivity chooses who has allergies and who does not.3 It was learned that allergies occur when people have a hypersensitivity to triggers, and in this instance, ragweed. This sensitivity follows across the board from allergy rhinitis to asthma, and as Leffert describes asthma as an immunologic hypersensitivity, sometimes where emotional stress triggers and exacerbates symptoms. One of the key components of asthma is when antigens sensitive a child and then these antigens trigger an immunologic reaction, i.e. an asthma attack. Likewise, for allergy rhinitis, it would seem that exposure to allergens, the body developing a hypersensitivity to these allergens, and then triggers by the allergens force allergies in the sufferer, i.e. hay fever or sneezing attacks such as when a burst of pollen from sniffing a flower itches the sufferer’s nose.

Through the past 100 years, medicine has continued to study allergy, the causes of allergy, and how to treat allergy. Questionnaires have been issued, studies have been tallied, and the basic findings are that allergies are expensive to treat, can often confound the pediatrician in charge of care, and clearly makes the victim of allergy suffer sometimes year round. Some questions used to decide if someone suffers from allergy are found in Table 4.4 The questionnaires studied for this paper generally follow an if-then format. If the sufferer experiences this symptom, then continue here, if not, go to this place. It is important to differentiate between colds, flu, and actual allergy symptoms. All studies used had a 95% confidence index, suggesting strong credibility.

Livestock as an Allergy Protection

Beginning with studies in the mid-90s, several European scientists in Sweden, the Netherlands, the UK, and other places in Europe, have been curious about the connections to allergies comparing urban and rural children. In the early 19th Century, it was thought that urban children had fewer allergies than rural kids did because at the time, rural places were cleaner than urban places, making exposure to allergens higher in urban places, rather than rural. Modern studies have found the opposite to be true. Ironically, studies from the past twenty years, mostly in Europe, have shown that exposure to farm animals has a protective affect against allergens, especially in regards to allergy rhinitis, or hay fever. Bråbäck illustrates the relationship between occupations and habitat in his 2004 article in Clinical & Experimental Allergy.5 Data is taken from Swiss conscript data from 1952 on. Although occurrences of allergy increased for habitats from both rural and urban dwellings, urban people had a higher increase and the gap between urban and rural grew larger.

Braun-Fahrländer and colleagues found, in 1999, that farming as a parental occupation decreased the risk of children developing symptoms of allergies.6 This paper has been documented in many following, suggesting a leading insight into this allergy conundrum. Braun-Fahrländer and colleagues hypothesized that children growing up on farms were less likely to be sensitized to common allergens and then that they would suffer less from allergic disease. To carry out their study, Braun-Fahrländer and colleagues used the Swiss Study on Childhood Allergy and Respiratory Symptoms with Respect to Air pollution (SCARPOL), a data set used by most of the European studies examined. Methods were a questionnaire at the school health services, a routine visit for the three ages groups studied, and blood samples for the older age groups. Of note in their findings was that farming families had a lower socio-economic status; had more children; had more humidity or visible mold in their home,;used traditional heating such as coal and wood; were more likely to keep furred pets, but the furred pets were less likely to be in the children’s bedroom; had mothers that were less likely to smoke; and had less hay fever, asthma, and eczema in their family history. From their findings, they discussed that the possibility exists that the living in an agricultural environment could provide a model of primary prevention. If this proves to be true, then, these findings could be taken into the urban environment as preventive maintenance for allergy sufferers.

Poultry – An Adverse Affect

Contrasting the European studies, a New Zealand study also looked at farms, children’s exposure to animals, and resistance to allergies as an adult.7 This study found that the children in the sample, their risk increased with exposure to farms. The most striking difference is the New Zealand study had more poultry, or in general poultry farms. The European studies did not, indicating that it is exposure to poultry that either increases or does nothing to the risk of being affected by allergy. Wickens, in Table 5 shows incidence where exposure to poultry nearly doubles the risk of hay fever compared to other triggers studied, such as cats and residence, the farm abode.8 Additionally, this study noted a higher incidence of allergy in regards to pigs and hay fever, farm abode in current allergic rhinitis, farm abode for asthma, and cats (inside or outside) regarding AEDS (skin problems).

The study discusses that all children living on farms had increased risk of all studied forms of allergy: hay fever, allergic rhinitis, asthma, wheezing, and eczema. Of the European studies examined, they concluded that living on farms with livestock had the protective affect against allergy later in life, but the published results did not pare down which animals were on the farms like this New Zealand study. On the other hand, the New Zealand study did not mention animals like cows (a European animal attributed to the protective affect), horses, goats, or other farm mammals besides pigs. Regardless, examining these causes in more detail and from a different vantage point, this study pushes further research to examine more fully which animals actually have the protective affect. If this is not done, one could believe that it may be something in the air in European farms rather than the animals present.

As a rebuttal to the New Zealand study, Braun-Fahrländer points out that having contact with farm animals shows the substantial decrease in the development of hay fever and asthma comparing children living on farms and non-farming children.9 He introduces in this editorial the ALEX study (ALlergy and EndotoXin) where dust samples were obtained from enrolled children and tests were done to see the development of IgE sensitization. Although not well supported, it was this sensitization that farm animals protect against, a known cause of allergy. Subsequently, although growing up on a farm does not suppress the process of IgE sensitization it protects against it. Still, though, animals remain undefined, and the New Zealand study, of the obtained articles, is the only one that specifies which animals were tested against.

Conclusions

In this paper I showed the debilitating affect allergy has on young people, studies showing links between livestock and allergy protection; and studies that show an adverse link in that protection, especially in regards to poultry. Several European studies over the past two decades have shown that when children live on farms with livestock, this experience later in life acts as protection against allergies, allergies that are increasing in society. This is important because of the discomfort and adverse affects to Quality of Life, the costs of health care for the afflicted persons, and the cost of healthcare for the public. If we can pinpoint what causes allergies, what can keep allergies at bay, and lastly how to overcome allergies, we would live in very different places than we do now. To take these findings further would be to introduce them into the planning stage of urban centers. If these findings could be more pinpointed for policy gurus, then we could try to make our cities allergy free. This would allow us to cure or control allergy at a local level with less cost to the individual and public. The next question could be, “Besides livestock, which animals that protect against allergies could be introduced as part of the urban landscape?” We’ve seen that poultry does not, so does that mean we need more dogs? Should every household enjoy the company of a dog, further reducing the need for places such as the Human Society?

References

• Asher, M.I., U. Keil, H.R. Anderson, et al. 1995. International study of asthma and allergies in childhood (ISAAC): rationale and methods. European Respiratory Journal. 8:483-491.
• Bråbäck, L., A. Hjern, and F. Rasmussen. 2004. Trends in asthma, allergic rhinitis and eczema among Swedish conscripts form farming and non-farming environments; a nationwide study over three decades. Clinical and Experimental Allergy. 34:38-43.
• Braun-Fahrländer, C. 2002. Do only European cattle protect from allergies? Allergy. 57:1094-1096.
• Braun-Fahrländer, C., M. Gassner, L. Grize, et al. 1999. Prevalence of hay fever and allergic sensitization in farmer’s children and their peers living in the same rural community. Clinical and Experimental Allergy. 29:28-34.
• Emanuel, M. B. 1999. Histamine and the antiallergic antihistamines: a history of their discovers. Clinical and Experimental Allergy. 29(supplement 3):1?11.
• Gerth van Wijk, R. 2002. Allergy: a global problem; Quality of life. Allergy. 57:1097-1110.
• Kilpeläinen, M., E.O. Terho, H. Helenius, and M. Koskenvuo. 2000. Farm environment in childhood prevents the development of allergies. Clinical and Experimental Allergy. 30:201-208.
• Leffert, Fred, M.D. 1978. Asthma: a modern perspective. Pediatrics. 62(6):1061-1069.
• Wickens, K., J.M. Lane, P. Fitzharris, et al. 2002. Farm Residence and exposures and the risk of allergic diseases in New Zealand children. Allergy. 57-1171-1179.

Tables & Figures

Table 1¹

Association of physician-diagnosed asthma during a lifetime with background factors in young Finnish adults. Adjustment performed by logistic regression model for all the other factors in the table and parental education.

	Total N*	Prevalence (%)*	Crude OR*	95% CI	P-value	Adjusted CR†	95% CI	P-Value
Place of Residene at Age 0-6 years
Rural non-farm	1,243	5.3	1.00			1.00
Farm	1,095	3.7	0.68	0.45-1.01	NS	0.70	0.46-1.06	NS
Urban	7,276	4.5	0.81	0.64-1.10	NS	0.81	0.61-1.07	NS
Day care outside the home at 0-2 years
No	9,324	4.5	1.00			1.00
Yes	1,127	5.1	1.14	0.86-1.52	NS	1.09	0.80-1.49	NS
Passive smoking at age 0-2 years
No	8,292	4.3	1.00			1.00
Yes	2,257	5.6	1.32	1.07-1.62	<0.01	1.30	1.03-1.64	<0.05
Gender
Male	4,142	5.1	1.00			1.00
Female	6,488	4.2	0.81	0.67-0.97	<0.05	0.72	0.59-0.88	<0.01
Parents’ asthma or atopy
No	6,258	2.9	1.00			1.00
Yes	4,299	6.39	2.46	2.04-2.97	<0.001	2.32	1.89-2.84	<0.001
Number of older siblings
0	5,672	4.9	1.00			1.00
1	3,597	4.3	0.88	0.72-1.08	NS	0.94	0.76-1.17	NS
2	920	4	0.82	0.58-1.16	NS	0.91	0.62-1.33	NS
3	256	3.5	0.71	0.36-1.40	NS	0.74	0.36-1.53	NS
?4	144	3.5	0.70	0.29-1.73	NS	0.90	0.36-2.25	NS

* Using all available information.

† For subjects with complete data on all the background variables.