e215 Pigeon feathers

Direct or indirect contact with bird allergens may cause sensitisation. Bird allergens may be major components of house dust.

Feral Pigeons build their nests in or on buildings and other structures, where they are usually found on ledges or in hollows - often under eaves or on girders. They may, however, be found in more rural situations, e.g., farmland, parks, golf courses, moorland and woodland.

GEOGRAPHICAL DISTRIBUTION

The number of domestic birds is currently estimated at 25 million in the USA and more than 8 million in German households. In Germany, an additional 11 million Pigeons are kept by more than 140 000 registered breeders of fancy Pigeons. (The Homing/Racing Pigeon is a specifically bred variety of Pigeon. These Pigeons are capable of returning home within the day after being released several hundred miles from their loft.) This number does not include the breeding of fattened Pigeons for the table.

There are over 300 species of Pigeons and Doves (names used interchangeably) around the world. Streptopelia is a genus of the dove family, slim, small to medium-sized, as compared to other doves, and many species have a patch on the neck. Originating from Africa but some species has spread over large parts of the Earth and are very popular among breeders and for competition.

The dove you often see in urban environment is the Feral, Town or City Pigeon (Columba livia) that is believed to have descended from domesticated strains of the Rock Dove. In the wild they then interbred (and continue to interbreed) with racing Pigeons and Pigeons from bird fanciers' lofts. The Feral Pigeon is found worldwide. It is closely associated with humans and is in fact often seen as a pest due to their droppings, voluminous nests and the noise they make, cooing and roof-scratching.

"Pigeon bloom" consists of keratin particles. These are produced copiously from feathers and transport serum proteins to peripheral airways and may act as a local irritant or adjuvant.

Well-defined major allergenic bands with molecular mass of 20-30 kDa and 67 kDa have been detected and identified in IgE immunoblots with feather extracts as well as with serum proteins of Budgerigar, Parrot, Pigeon, Canary, and Hen. Inhalable feather dust was shown to contain several allergenic components which cross-react with serum allergens/antigens of the same as well as of other bird species (1). These allergens have not yet been fully characterised.

The allergens detected to date include numerous proteins in Pigeon serum (2-3). Pigeon intestinal mucin, an allergen found in Pigeon droppings, may also be found in Pigeon sera and feathers (4).

As noted above, inhalable feather dust contains several allergenic components which cross-react with serum allergens/antigens of the same as well as of other bird species (1).

IgE-mediated reactions

Asthma, allergic rhinitis and allergic conjunctivitis may occur after exposure to Pigeons (5-7). Other diseases associated with exposure to Pigeon include extrinsic allergic alveolitis/hypersensitivity pneumonitis, asthma, allergic rhinitis, ornithosis (microbial infections transmitted to man) and lung inflammation caused by irritant dusts (8).

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 is also known as Pigeon Breeder's Disease, an example of hypersensitivity lung disease due to the inhalation of Pigeon-derived antigens.

The disease occurs after exposure to organic dust, especially after close contact with Pigeons or other birds such as Budgerigars, Parrots, Canaries, Parakeets, Cockatiels, Doves or Finches. Exposure results in the development of immunoglobulin antibodies including IgE (1), IgM (9), IgA and various IgG subclasses (10-12). The antibodies may be found in the sera and saliva of patients (13) as well as in the sera of asymptomatic but exposed subjects (14).

The allergenic proteins may be found in bird serum, droppings, skin scales, feathers and, in the case of Pigeons, Pigeon bloom (a waxy fine dust which coats the feathers of Pigeons). Contact may result from handling birds, cleaning their lofts, or exposure to the organic dust drifting down from a ceiling or roof where birds nest.

Diagnosis is based on a characteristic clinical picture and a typical x-ray pattern, accompanied by the presence of specific IgG antibodies (15).

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 (16).

A typical clinical presentation would be a male Pigeon breeder who develops a sudden fever, cough and dyspnea with diffuse nodular shadows on the chest X-ray film (17). In a study conducted in the Canary Islands, of 343 Pigeon breeders, 29 (8%) fulfilled the classic Pigeon Breeder's Disease criteria. One hundred and six (31%) had rhinitis, 62 (19%) had immediate bronchial symptoms, and 51 (15%) suffered from chronic bronchitis. A significant level of specific IgG was detected in 139 (40%) cases. A statistical relationship between the intensity of exposure and specific IgG response was also found (15).

Other reactions

The House Dust Mite Dermatophagoides farinae was found in 5 samples derived from conventional Hen housing with fowls and Pigeons and from a test animal hutch with Rats, Mice and Rabbits. Besides Mites of the family Pyroglyphidae, Mites of the Tyroglyphidae family and/or mucedine were found, which affects the development of Mite populations. House Dust Mites should be considered in the aetiology of allergic diseases from Dog, Cat and livestock (18).

Feather Mites are a major source of soluble proteins derived from feathers, accounting for up to 10% of the total weight of the feather. RAST inhibition indicated feather Mites had species-specific epitopes as well as ones that cross-reacted with Dermatophagoides pteronyssinus (19-20).

A case has been reported where acute urticaria was caused by Pigeon Ticks, which had dropped from wooden ceiling beams. The patient was living in the center of Milan in a very old house, where numerous Pigeons had built their nests under the rooftop (21).

Cryptococcus neoformans is a Yeast with a large polysaccharide capsule that may be found in Pigeon droppings and result in opportunistic infections in man, but not in Pigeons. Inhalation of spores can cause pulmonary infection, although this is usually mild and sometimes even asymptomatic (22).