Investigation of choice for hydatid disease is: September 2009
**Question:** Investigation of choice for hydatid disease is: September 2009
**Core Concept:** Hydatid disease is a zoonotic infection caused by the larvae of the Echinococcus tapeworm. The most common form is caused by Echinococcus granulosus, and it affects the liver and lungs most frequently. Diagnosis is often challenging due to the variable clinical presentation and the lack of specific symptoms.
**Why the Correct Answer is Right:**
The correct answer, D. Serology (IgG ELISA), is the most appropriate investigation for diagnosing hydatid disease. IgG ELISA (Enzyme-Linked Immunosorbent Assay) detects the presence of specific antibodies (IgG) against the Echinococcus granulosus antigens in the patient's blood. This test is highly sensitive and specific, making it ideal for diagnosing the infection.
**Why Each Wrong Option is Incorrect:**
A. Radiography (X-ray): Although X-rays can show calcified cysts, they may not always be present, leading to false negative results. Radiography is not the most sensitive or specific investigation for hydatid disease diagnosis.
B. Ultrasonography: Ultrasonography is a useful tool for detecting liver and lung hydatid cysts, but its sensitivity and specificity may vary. It is not the gold standard for diagnosis.
C. Serology (IgM ELISA): IgM ELISA is a less specific test, as it detects IgM antibodies, which are not specific to hydatid disease and can be present in other infections or diseases.
**Clinical Pearl:** A high index of suspicion and a combination of investigations are necessary for diagnosing hydatid disease. A definitive diagnosis involves a combination of clinical findings, imaging modalities, and serological tests.
**Correct Answer:** D. Serology (IgG ELISA)