Parasitic Diseases of the Lung and Pleura
- Hydatid disease is characterized by the development of cysts as a consequence of the parasitization of humans by the larva of Echinococcus.
- Protozoal infections include amebiasis, which is a parasitic infection produced by Entamoeba histolytica.
- Helminthic infections, such as Dirofila riaimmitis (also known as heartworm in dogs), produce pulmonary dirofilariasis in people.
The term parasite is derived from a Greek word meaning “he who eats at the table of another.” Although in a broader sense all infectious microorganisms could be considered parasites, the term parasitic infections refers to those infections caused by protozoa and helminths. Their main feature is their transmission to humans via biologic vectors or intermediate hosts (insects, mollusks, or mammals). Once lodged in the definitive host, they present complex life cycles and produce long-term chronic infections.
Parasitic diseases of the chest can manifest as hypersensitivity reactions, as eosinophilic lung disease, or as direct invasion of the lungs or pleura. The clinical profile to watch for is peripheral blood eosinophilia in immunocompetent individuals who have traveled to endemic regions. The other group at great risk comprises those who are immunocompromised, such as organ transplant recipients and patients with acquired immunodeficiency syndrome (AIDS), in whom the prevalence is notably higher.
The presence of eggs or larvae in stool, sputum, bronchoalveolar lavage fluid, pleural fluid, or lung tissue generally indicates pleuropulmonary involvement, although this is an exceptional finding. Therefore, the diagnosis is usually based on serologic evidence provided by enzyme-linked immunosorbent assay (ELISA) or monoclonal antibodies.
This chapter, which is directed particularly to thoracic surgeons, reviews all the parasitic diseases that affect humans, particularly those found in pleura or lungs. They have been grouped into tables for easy referral (Tables 1-4). Hydatid disease, which is endemic not only in the Mediterranean basin but also in regions as widely dispersed as Australia and South America, is dealt with in particular depth. It occasionally requires surgical intervention, whereas other parasitic infections can almost always be treated successfully without surgery.
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