Eosinophilia in returning travelers and migrants.

INTRODUCTION Eosinophilia in travelers returning from tropical countries is often caused by helminths. The high eosinophil counts arise particularly from tissue migration of invasive larvae. METHODS Review of literature selected by means of a Medline search using the MeSH terms "eosinophilia" and "helminth." RESULTS The patient's geographic and alimentary history may suggest infection with particular parasitic worms. A targeted diagnostic approach is suggested. The physician should concentrate on the principal signs and be guided by the geographic and alimentary history. Elaborate diagnostic measures are seldom indicated. DISCUSSION Although eosinophilia alone has low positive predictive value for a worm infection, it points clearly to helminthosis if the patient has recently returned from the tropics and the eosinophilia is new.