An unusual case of life-threatening visceral larva migrans (toxocarias
is) is reported herein. The patient was admitted with acute dyspnea an
d bilateral pleural effusion; rapidly pericardial tamponade developed.
Blood and body fluid eosinophilia were elevated. Extensive investigat
ions revealed no malignant process or vasculitis, but Toxocara infecti
on was confirmed by rising specific antibody titers. The high seroprev
alence of Toxocara antibodies, particularly in children, suggests that
a diagnosis of visceral larva migrans should be considered before a d
iagnosis of systemic hypereosinophilic syndrome even when clinical pre
sentation is unusual. Prophylaxis against this widespread polymorphic
zoonotic infection is desirable in view of the potentially dramatic co
nsequences of infestation.