What causes the eosinophilic infiltrate seen in Loeffler endocarditis?

The eosinophilic infiltrate observed in Loeffler endocarditis is primarily caused by a parasitic infection, specifically related to the presence of certain parasites like Strongyloides stercoralis or Toxocara canis. This condition is characterized by an infiltration of eosinophils, which are a type of white blood cell that typically responds to parasitic infections and allergic reactions.

In Loeffler endocarditis, the underlying parasitic infection leads to an immune response that results in significant eosinophilia, contributing to the inflammation and damage in the heart tissue and valves. The eosinophils in this condition are believed to play a role in both the pathogenesis of the disease and the inflammatory response against the parasites.

The distinction between various causes like allergic reactions, malignancy, or bacterial infections lies in the fact that they do not primarily trigger the same type of eosinophilic infiltration as seen in Loeffler endocarditis. While allergic reactions can cause eosinophilia, in the context of Loeffler endocarditis, the initiating factor is specifically the parasitic infections and their subsequent immune-mediated effects on cardiac tissues.