Route Of Exposure

The Chicken (which probably originated as a jungle fowl in southwestern Asia) was one of the earliest animals to be domesticated, possibly as early as 4000 BC. They were popular in China and among the Greeks and Romans, and are now distributed virtually throughout the world. They form by far the most important class of poultry, raised principally for their meat and eggs. The current trend is towards specialisation, with some Chicken raisers producing hatching eggs, others eggs for table use, and others raising Chickens to market as meat. Many distinct Chicken breeds have been combined through selective breeding into a few relatively standard types that are notably efficient converters of feed into meat or eggs. The dominant meat Chicken today is a cross between the fast-growing female White Plymouth Rock Chicken and the deep-breasted male Cornish Chicken. The predominant egg-laying type in the United States today is the White Leghorn Chicken.

Breeders as well as workers in the Chicken food processing industry are examples of groups with high risk of exposure. Other means of exposure are pillows made of Chicken feathers, arts and crafts that include Chicken feathers, and wing feathers used in fletching arrows. A few breeds of Chicken are raised chiefly for their ornamental appearance or as pets.

Clinical Relevance

Allergen description

No allergens have yet been characterised.

Allergen exposure may occur from contact with Chicken feather, Chicken serum or Chicken droppings. Chicken droppings may contain, similarly to Pigeon droppings, excreted serum protein antigens, which may have been degraded, making identification difficult. Droppings may also include bacterial endotoxin and other non-species-specific biological substances.

Potential Cross Reactivity

Positive IgE antibody reactions to sera and feathers from five bird species (Pigeon, Budgerigar, Parrot, Canary and Hen), and to Pigeon droppings, have been found in subjects with Bird Fancier's Asthma. Since antibodies of each of the patients also recognised antigens of birds with which they were not in contact, immunological cross-reactivity between different avian species was suggested.

Clinical Experience

IgE mediated reactions

Asthma, allergic rhinitis and allergic conjunctivitis may result following exposure to Chicken feathers, epithelial cells or droppings. The allergic manifestations may present as Bird Fancier´s Asthma and as so-called Bird-Egg Syndrome with symptoms such as rhinitis, urticaria and angioedema, and also gastro-intestinal problems. Contact with Chicken has been reported as a common cause of occupational asthma and allergic rhinitis.

Contact with Chicken is a significant cause of sensitisation in poultry workers. Asthma prevalence in farmers has been found by means of a questionnaire survey to be higher for Horse breeders/groomers, Pig farmers, poultry farmers, and those working with Oats. Up to 17.4% of poultry farmers reported symptoms of asthma. In an avian slaughterhouse, workers may be exposed to Chicken feathers, as well as to serum and droppings allergens. Sensitisation in these individuals may also occur to Chicken feed.

Extrinsic allergic alveolitis, also known as hypersensitivity pneumonitis, Bird Fancier's Lung and Farmer's Lung, is a disease of inflammation of the lung parenchyma in the terminal bronchioles and alveoli. Symptoms may start soon after exposure to bird allergens or after many years, and may include breathlessness, cough, occasional chills, and fever. Death may also result.

The disease occurs after exposure to organic dust, especially after close contact with Chickens or other birds such as Pigeons, Budgerigars, Parrots, Canaries, Parakeets, Cockatiels, Doves or Finches. Exposure results in the development of immunoglobulins including IgE, IgM, IgA and various IgG subclasses. The antibodies may be found in the sera and saliva of patients.

The allergenic proteins may be found in bird serum, droppings, and feathers.

Contact may result from handling birds, cleaning their cages, or exposure to the organic dust drifting from where the birds reside.

Diagnosis is based on a characteristic clinical picture and a typical x-ray pattern, accompanied by the presence of specific IgG antibodies.

The measurement of specific IgG using IgG tracer technology has been shown to be a sensitive and specific assay for the routine diagnostic testing of extrinsic allergic alveolitis.

Other reactions

Chicken droppings may contain Histoplasma capsulatum, resulting in the granulomatous disease histoplasmosis.

Mites may also be a major allergen in poultry farmers. Northern Fowl Mite (Ornithonyssus sylviarum) residing in Chicken feathers may be the predominant allergen causing occupational allergy in poultry farmers. The House Dust Mite Dermatophagoides evansi was documented in dust samples from poultry farms, as well as the House Dust Mite Dermatophagoides farinae, Mites of the Tyroglyphidae family and/or Mucedine family. Storage Mites and other predatory Mites were also found in these samples. Aleuroglyphus ovatus is a Storage Mite that has a worldwide distribution and has been found in stored bran, Wheat, Chicken meal, and dried fish products.

Farm workers handling animal feeds are exposed to a variety of chemicals, some of which may cause allergic contact dermatitis. A case of allergy to ethoxyquin (a preservative added to Chicken feed to inhibit vitamin degradation) in a Chicken farmer is reported.