Understanding Loffler's Syndrome Cause

Loffler's syndrome is a clinical condition characterized by transient pulmonary infiltrates accompanied by eosinophilia in the blood and lungs.

Identifying the Infecting Agent

This syndrome is specifically associated with the larval migration phase of certain helminthic (parasitic worm) infections through the lungs. Among the given options, infection by Ascaris (a type of roundworm) is a well-known cause of Loffler's syndrome.

Mechanism of Loffler's Syndrome

• When Ascaris eggs are ingested, larvae hatch in the intestine.
• These larvae penetrate the intestinal wall and migrate through the bloodstream to the lungs.
• As they pass through the lung tissue (alveoli), they cause inflammation and an accumulation of eosinophils, leading to the characteristic infiltrates and symptoms.
• While other parasites like *Strongyloides* can cause eosinophilic lung disease, Ascaris is classically linked to Loffler's syndrome.

Therefore, Loffler's syndrome is caused due to infection by Ascaris.