Leucocytozoon simondi infection in European and American eiders.

An adult European eider (Somateria mollissima mollissima) died at the St Louis Zoo and was found to be infected with numerous blood and tissue stages of Leucocytozoon simondi. Necropsy revealed massive air sac aspergillosis, but histologic examination revealed a diffusely distributed protozoon organism that was identified as L simondi. Examination of tissues from a previously necropsied European eider and from 2 American eiders (Somateria mollissima dresseri) that later died also revealed evidence of L simondi infection.