Duck is the common name for wild and domestic waterfowl of the family Anatidae, which also includes Geese and Swans. It is the largest and most diverse group of waterfowl, and is hunted and bred for its meat, eggs, and feathers. Strictly speaking, Duck refers to the female and drake to the male. The ancestor of all domestic breeds (except the Muscovy of South American origin) is the Mallard, Anas boscas, which is found in Europe, Asia, and North America.

Ducks' environment usually depends on which of the 3 main groups they belong to: the surface-feeding Ducks such as the Mallard, Wood Duck, Black Duck, and Teal frequent ponds, marshes, and other quiet waters; the diving Ducks such as the Canvasback, Scaup, Scoter, Eider, and Red Head are found on bays, rivers, and lakes; and the fish-eating Ducks, the Mergansers, with slender, serrated bills, also prefer open water. Ducks make long migratory flights. In northern countries a portion of the down with which the Eider Ducks line their nests is systematically collected and used to stuff pillows and duvets. Large numbers of Ducks are raised in captivity and semi-captivity, especially in East Asia.

IgE mediated reactions

Asthma, allergic rhinitis and allergic conjunctivitis may result following exposure to Duck feathers, epithelial cells or droppings. The allergic manifestations may present as extrinsic allergic alveolitis (1).

Of 269 adult patients with suspected skin and respiratory allergies tested for feathers with skin-specific IgE tests, 9% of the whole group and 14% of those positive to inhalant allergens were positive to any feather allergen. Two reacted to Duck feathers, 12 to goose and 15 to chicken feathers. Symptoms were reported by 58% of patients who were skin-specific IgE positive to feather and 55% by other skin-specific IgE positive patients. Positive RAST specific IgE test was surprisingly very low (2).

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 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.

Exposure to avian antigens results in the development of immunoglobulin antibodies including IgE (3), IgM (4), IgA and various IgG subclasses (5-7). The development of specific antibodies does not necessarily indicate disease. Forty-two workers from a poultry abattoir were examined for serum antibodies to Duck antigens and compared with healthy blood donors. The levels of IgG and IgA antibodies to Duck serum were significantly higher in poultry workers. In workers employed for less than 1 year the antibody levels were lower than in those who had been employed for a longer period of time. The IgA antibody level to a high molecular weight Aspergillus antigen was higher in poultry workers than blood donors, whereas the level of other Aspergillus antibodies were similar in the 2 groups. No cases of allergic alveolitis were found (8).

Diagnosis is based on a characteristic clinical picture and a typical x-ray pattern, accompanied by the presence of specific IgG antibodies (9).

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 (10).

Clinical allergy to commercial feather products is less common than usually thought, as a result of the removal of rough-dry dust, washing and drying at 125OC. The allergens derived from unrefined feathers include bird serum proteins, bird droppings, and feather Mites (2).

Other reactions

Polyester-filled pillows contain significantly more total weight of Der p 1 Mite allergen (Dermatophagoides pteronyssinus) than feather-filled pillows (11).

No allergens have yet been characterised.

Cross Reactivity

Cross-reactivity between Chicken and other phylogenetically related bird species may be expected, and in Chicken-allergic patients, significant IgE titers to Parrot, Budgerigar, Chicken, Pigeon, Goose and Duck have been reported (12, 13).