Respiratory tract infection Unusual infection by anatomical site Unusual upper respiratory tract infection Recurrent or severe sinopulmonary infections are characteristic of humoral (B-cell) deficiencies, complement defects, and phagocyte disorders. This phenotype is also frequently observed in combined immunodeficiencies (e.g., DOCK8 deficiency) and hyper-IgE syndromes (e.g., STAT3 deficiency). Increased susceptibility to infection of the upper respiratory tract, as manifested by recurrent or severe infection of the nose, sinuses, pharynx, larynx, or middle ear, or by infection caused by an atypical or opportunistic organism.