Ascaris lumbricoides
Parasites cause eosinophilic pneumonia in three different ways. Parasites can either invade the lungs, live in the lungs as part of their life cycle, or be spread to the lungs by the bloodstream. Eosinophils then migrate to the lungs in order to fight the parasites, and cause eosinophilic pneumonia when they release their contents. Important parasites that invade the lungs include "Paragonimus" lung flukes and the tapeworms "Echinococcus" and "Taenia solium". Important parasites which inhabit the lungs as part of their normal life cycle include the worms (helminths) "Ascaris lumbricoides", "Strongyloides stercoralis" and the hookworms "Ancylostoma duodenale" and "Necator americanus". When eosinophilic pneumonia is caused by helminths, it is often called "Löffler's syndrome". The final group of parasites cause eosinophilic pneumonia when their eggs are carried into the lungs by the bloodstream. This can include "Trichinella spiralis", "Strongyloides stercoralis", "Ascaris lumbricoides", the hookworms, and the schistosomes.