I will try and answer as many of your questions as I can, but some, at least to my knowledge and according to a search of the literature, are not answerable.
I cannot tell you the incidence of bird allergy in the United States. I found no studies citing any such incidence, but we do know at least that there are about 6.4 million United States households that have one pet bird (1). If one assumes that 10 to 20% of the population has a predisposition to develop allergic respiratory tract disease, one could assume that there might at least be a million or so individuals with allergic responses to these birds unless, of course, this figure would be less because those who do experience such reactions might give up pet bird ownership.
In addition to the above reference, the Marks article in Annals of Allergy (abstract copied below) might give you some further insight into the incidence of allergy to pet birds. As you can see from this abstract, in 1984 there were 25 to 30 million pet birds in the United States.
Unfortunately, to my knowledge there are no studies looking at "which type of bird is most allergenic." So I cannot answer that question.
As you can see from the abstracts copied below, the source of allergen can be feathers, dander, or serum, and the allergen can vary with the type of bird.
Also you will see an abstract copied below where the mites associated with birds can produce respiratory allergy as well.
Thank you again for your inquiry and we hope this response is helpful to you.
1. American Pet Products Manufacturer's Association; 2005/2006 National Pet Owners Survey. In Greenwich, CT, American Pet Products Manufacturer's Association 2005.
Ann Allergy. 1984 Jan;52(1):56-7.
Respiratory tract allergy to household pet birds.
Pet birds may be as great an allergenic problem as cats and dogs. Some of the estimated 25 to 30 million pet birds in the United States may cause such allergic symptoms as nocturnal wheezy cough, asthma, rhinitis, conjunctivitis or other manifestations during a short or long period of induction. Most of the 62,000 exotic birds imported each month are members of the psittacine or parrot family. Such birds may be particularly troublesome in that they pollute the home environment by antigenic discharges from their integument.
Clin Exp Allergy. 1997 Jan;27(1):60-7.
Feather mites are potentially an important source of allergens for pigeon and budgerigar keepers.
Colloff MJ, Merrett TG, Merrett J, McSharry C, Boyd G.
Background: Previous studies on allergy to feathers have not addressed whether organisms living on feathers (mites, lice, moulds) are a source of allergens.
Objective: To investigate whether feather mites produced allergens of clinical relevance to bird keepers.
Methods: We examined serum IgE responses of 96 pigeon breeders to an extract of feather mites from pigeons (predominantly Diplaegidia columbae), using Western blotting, specific IgE assay using AlaSTAT EIA and RAST inhibition.
Results: Feather mites are a major source of soluble proteins derived from feathers, accounting for up to 10% of the total weight of the feather. Forty-three sera had a negative score (0) for anti-feather mite IgE, 27 were weakly positive (1-2) and 26 had strongly positive scores (3-4). Fewer pigeon breeders with scores > or = 3 were asymptomatic than those with negative scores (12 versus 40%), more had late onset symptoms (with or without early onset symptoms: 77% versus 44%) and had IgE antibody against house dust mite (89% versus 23%). Western blotting of eight sera against the extract of Diplaegidia columbae revealed 20 IgE-binding components ranging from 22 to 200 kDa. A high diversity of components was recognized by each serum: arithmetic mean 7 (range 2-14). RAST inhibition indicated feather mites had species-specific epitopes as well as ones that cross-reacted with Dermatophagoides pteronyssinus.
Conclusions: Strongly-positive AlaSTAT scores to pigeon feather mite were associated with allergic symptoms of late onset in pigeon breeders. We conclude that feather mites are a major source of clinically-relevant allergens for pigeon breeders.
Int Arch Allergy Appl Immunol. 1985;77(4):433-7.
Immunoglobulin E antibodies against budgerigar and canary feathers.
van Toorenenbergen AW, Gerth van Wijk R, van Dooremalen G, Dieges PH.
In 212 sera from budgerigar and canary fanciers with symptoms of rhinitis and/or bronchial asthma, IgE antibodies against budgerigar feathers (Budf) or canary feathers (Canf) were determined. In 25 of 98 Canf-specific IgE antibody measurements, and in 28 of 154 Budf-specific IgE antibody measurements, a significant (6% or more binding of 125I-anti-IgE) level of specific IgE was found. In 3 sera with the highest levels of Canf- or Budf-specific IgE, IgE antibodies against sera from both birds were present. It is concluded that IgE antibodies against canary and/or budgerigar feathers are present in about 20% of canary and budgerigar fanciers with symptoms of atopic disease. Canary and budgerigar feathers contain IgE-binding antigens that are not present in the corresponding bird sera and droppings.
Int J Occup Med Environ Health. 2011 Sep;24(3):292-303. doi: 10.2478/s13382-011-0027-x. Epub 2011 Jul 29.
Occupational allergy to birds within the population of Polish bird keepers employed in zoo gardens.
Swiderska-Kielbik S1, Krakowiak A, Wiszniewska M, Nowakowska-Swirta E, Walusiak-Skorupa J, Sliwkiewicz K, Palczynski C.
Objectives: To evaluate the risk factors for the development of occupational allergy to birds among Polish zoo garden keepers.
Methods: A total of 200 bird zookeepers employed in the Polish zoo gardens in KLódz, Warsaw, Gdansk, Chorzów and Plock and exposed occupationally to bird allergens were examined using a questionnaire, skin prick tests (SPTs) to common allergens and bird allergens, spirometry and cytograms of nasal swab. The level of total IgE in serum and serum-specific IgE to parrot, canary, pigeon feathers and serum were also evaluated.
Results: Eight percent of bird zookeepers were sensitized to at least one of the bird allergens. The most frequent allergens yielding positive SPT results were D. farinae - 32 cases (16%), D. pteronyssinus - 30 cases (15%) and grass pollens (16.5%). In the studied group, allergen-specific IgE against bird allergens occurred with the following frequency: 87 (43.5%) against canary feathers and/or serum, 80 (40%) against parrot feathers and/or serum and 82 (41%) against pigeon feathers and/or serum. Occupational allergy was diagnosed in 39 (26.5%) cases, occupational rhinitis was present in 22 (15%) cases, occupational asthma in 20 (13.6%) subjects, occupational conjunctivitis in 18 (12.2%) cases, whereas occupational skin diseases in 11 (7.5%) cases. More eosinophils were found in nose swab cytograms among bird zookeepers with occupational airway allergy.
Conclusions: The findings indicate that occupational allergy to birds is an important health problem among zoo bird keepers in Poland.
Clin Allergy. 1987 Nov;17(6):515-21.
Nasal allergy to avian antigens.
Gerth Van Wijk R1, Van Toorenenbergen AW, Dieges PH.
This study describes the case of a patient who developed symptoms of rhinoconjunctivitis on exposure to budgerigars and parrots. An IgE-mediated allergy to budgerigar, parrot and pigeon antigens was demonstrated using both in-vivo challenge tests (skin and nasal provocation tests) and in-vitro investigations (radio-allergo-sorbent test, histamine release test). The study shows that the development of nasal disease can be associated with allergy to avian antigens.
Phil Lieberman, M.D.