Sheep epithelium

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Code: e81
Latin name: Ovis spp.
Family: Bovidae
Common names: Sheep, Domestic sheep
Direct or indirect contact with animal allergens frequently causes sensitisation.

Allergen Exposure

Geographical distribution
Sheep were first domesticated c. 7,000 years ago, and the first use of their fleeces for wool is dated c. 4000 BC. (Wild Sheep, found in mountainous parts of Asia, North America, and the Mediterranean region, are agile rock climbers with large, spiraling horns. They do not bear wool.) The present-day breeds of domesticated Sheep vary greatly because they were developed for different purposes and environments. Sheep are bred for their wool, meat (mutton or lamb, according to age), skins, and, in certain parts of Europe and the Middle East, their milk, from which cheese is made. Among the important breeds are the Columbia, Cotswold, Dorset, Hampshire, Karakul, Leicester, Lincoln, Merino, Oxford, Rambouillet, Shropshire, Southdown, and Suffolk Sheep.
 
Environment
Sheep are found mostly in temperate climates and thrive on roughage. They tend to be kept in herds. Their wool is one of the most common sources of textiles in human culture.
 
Allergens
No allergens from this animal have yet been characterised.

Potential Cross-Reactivity

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Clinical Experience

IgE-mediated reactions
Exposure to epidermal allergens may result in asthma, allergic rhinitis and allergic conjunctivitis (1).
 
In a Spanish questionnaire-based study of 1,164 farmers, with 808 subjects included after non-exposed workers were excluded, Sheep workers reported the highest prevalence of chronic phlegm (38.5%), work-related symptoms (53.9%) and symptoms of organic dust toxic syndrome (35.9%) (2).
 
Other reactions
Allergy reactions to Sheep wool have been described, but conflicting results are apparent.
 
A study reported that in early stages of wool processing the overall frequency of respiratory work-related symptoms was low and mainly nasal and/or ocular. The symptoms were not related to the stage of processing. Serum-specific IgE against wool extracts was not detectable (3).
 
In 64 wool textile workers, skin testing was performed with different wool allergens (domestic and Australian). The prevalence of positive skin-specific IgE to all allergens was higher in wool than in control workers, although the difference was statistically significant only for washed domestic wool (wool workers: 42.2%; control workers: 19.6%). Increased serum IgE levels were more frequent in wool (26.6%) than in control workers (3.1%). In wool textile workers there was a high prevalence of acute and chronic respiratory symptoms. Many of the wool workers had an FEF25 lower than 70% of that predicted. The authors report that, in general, the prevalence of symptoms and the lung function abnormalities did not correlate with the results of specific (wool) skin tests, but that their data suggested that exposure to wool dust in some workers may be associated with the development of acute and chronic respiratory symptoms and impairment of lung function, and that immunological abnormalities, although frequent in this group, did not appear to be associated with the severity of these changes (4).
 
Occupational dermatitis in Ewe milkers has been reported. This may be as a result of contact with milk rather than Sheep epithelium (5-6). IgE-mediated hypersensitivity resulting in respiratory crisis in a young man every time he milked his Sheep has been reported (7).
 
Sheepskins may be a source of House Dust Mite and Cat allergens, as they rapidly accumulate allergens from the domestic environment. Sheepskins as infant bedding should be discouraged for infants at risk of sensitisation to House Dust Mites and Cats (8-9).
 
Compiled by Dr Harris Steinman, harris@zingsolutions.com

References

  1. Radon K, Danuser B, Iversen M, Jorres R, Monso E, Opravil U, Weber C, Donham KJ, Nowak D. Respiratory symptoms in European animal farmers. Eur Respir J 2001;17(4):747-54
  2. Magarolas R, Monso E, Aguilar X, Radon K, Nowak D, Martinez C, Morera J. Prevalence and risk factors of respiratory symptoms in farmers; comment. [Spanish] Med Clin (Barc) 2000;114(18):685-9
  3. Moscato G, Catenacci G, Dellabianca A, Lecchi A, Omodeo P, Manfredi S, Tonin C. A respiratory and allergy survey in textile workers employed in early stages of wool processing. G Ital Med Lav Ergon 2000;22(3):236-40
  4. Zuskin E, Kanceljak B, Mustajbegovic J, Godnic-Cvar J, Schachter EN. Immunological reactions and respiratory function in wool textile workers. Am J Ind Med 1995;28(3):445-56
  5. Gallo R, Cozzani E, Brusati C, Guarrera M. Ewe milker's hand dermatitis. Contact Dermatitis 2000;42(6):361-2
  6. Quirce S, Olaguibel JM, Muro MD, Tabar AI. Occupational dermatitis in a ewe milker. Contact Dermatitis 1992;27(1):56
  7. Vargiu A, Vargiu G, Locci F, Del Giacco S, Del Giacco GS. Hypersensitivity reactions from inhalation of milk proteins. Allergy 1994;49(5):386-7
  8. Siebers RW, O'Grady GB, Fitzharris P, Crane J. House dust mite allergen accumulation on sheepskins. N Z Med J 1998;111(1076):408-9
  9. Sawyer G, Kemp T, Shaw R, Patchett K, Siebers R, Lewis S, Beasley R, Crane J, Fitzharris P. Biologic pollution in infant bedding in New Zealand: high allergen exposure during a vulnerable period. J Allergy Clin Immunol 1998;102(5):765-70

 

As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.