Type of parasite: nematode
Species: Dirofilaria immitis
Transmission: Microfilaria are passed by mosquito, from an infected dog to the human. The larvae develop in subcutaneous tissue and then pass into the circulation to the lung.
Clinical features:
(1) A noncalcified coin lesion is seen on a chest X-ray in the lung (often the right lung) of an adult. The presumed preoperative diagnosis is either cancer or granuloma.
(2) The patient may or may not have pulmonary symptoms (cough, etc).
(3) The person lives or has lived in a tropical, subtropical or warm temperate region endemic for Dirofilaria immitis.
Laboratory findings:
(1) A biopsy of the lung lesion shows a pulmonary arterial thrombosis with an ischemic infarct. Within the lesion are larvae which can be found if multiple section are examined.
(2) A mild eosinophilia may be present.
(3) Microfilaria are absent from the peripheral blood.
