Parasitic infections are endemic in developing countries located in tropical and subtropical regions. Risk of parasitic infection also extends to some groups in industrialized countries, including travelers, immigrants, institutionalized populations, and AIDS patients.¹

Many parasitic infections that are common in Asian countries can lead to pulmonary lesions. These include toxocariasis, paragonimiasis, malaria, amebiasis, ascariasis, and strongyloidiasis.

Parasitic infection is one of the main causes of eosinophilia, which is defined as the presence of more than 500 eosinoph ils/L in peripheral blood. Eosinophilia may be accompanied by eosinophilic infiltration in tissue. Focal eosinophilic infiltration in the lungs and liver is relatively common and is often associated with a parasitic infection, drug hypersensitivity, allergic diseases, and collagen vascular diseases. It is also associated with internal malignancies such as Hodgkin's lymphoma as well as lung, stomach, pancreatic, or ovarian cancer.²

A finding of incidental peripheral eosinophilia may prompt further clinical workup in many patients with parasitic infections. Enzyme-linked immunosorbent assay (ELISA) for specific parasitic organisms (e. g., Paragonimus westermani or Toxocara canis) can help confirm a diagnosis of parasitic pulmonary infection.

• Toxocariasis (caused by the nematode Toxocara can is). T canis is the intestinal parasite of dogs, foxes, and other canids, and it is distributed worldwide. It is a main cause of so - called visceral larva migrans, the inflammatory reaction caused by migrating larvae of nematodes through the human viscera.³