Tropical pulmonary eosinophilia is caused because of –
**Core Concept**
Tropical pulmonary eosinophilia (TPE) is a condition characterized by an intense eosinophilic infiltration of the lungs, leading to respiratory symptoms and pulmonary function abnormalities. This condition is a hypersensitivity reaction to filarial parasites, particularly Wuchereria bancrofti.
**Why the Correct Answer is Right**
The correct answer is related to the pathogenesis of TPE, which involves an overactive immune response to filarial antigens. Eosinophils, a type of white blood cell, play a key role in this reaction. They are attracted to the lungs by chemokines and cytokines released in response to filarial antigens, leading to their accumulation and subsequent tissue damage. This results in symptoms such as cough, wheezing, and shortness of breath.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because TPE is not caused by a bacterial infection. While bacterial infections can cause eosinophilia, TPE is a specific condition related to filarial parasites.
**Option B:** This option is incorrect because TPE is not caused by a viral infection. Viral infections can cause pulmonary symptoms, but TPE is a hypersensitivity reaction to filarial antigens.
**Option C:** This option is incorrect because TPE is not caused by an allergic reaction to an inhaled substance. While allergic reactions can cause eosinophilia, TPE is a specific condition related to filarial parasites.
**Clinical Pearl / High-Yield Fact**
TPE is a classic example of a Type I hypersensitivity reaction, characterized by the release of histamine and other chemical mediators from mast cells, leading to increased vascular permeability and smooth muscle contraction.
**Correct Answer:** D.