Eosinophilia in the returning traveler.

An elevated eosinophil count is a common, frequently underrecognized finding in travelers returning from the tropics and elsewhere. Although there are multiple causes of eosinophilia in a traveler, it is often related to an acquired helminth infection. In some cases these infections can be benign and self-limiting, but in others it may lead to severe sequelae for the individual or others. This article outlines the etiology and diagnosis of eosinophilia concentrating on helminth infections.