Domestic Parasitic Infections in Patients with Asthma and Eosinophilia in Germany - Three Cases with Learnings in the Era of Anti- IL5 Treatments.

Eosinophilic inflammation is a hallmark of asthma, and blood eosinophilia has been established as a biomarker for phenotyping asthma and predicting the response to anti-IL5 treatments. Although parasitic infections are rare in European adults, they remain an important differential diagnosis for blood eosinophilia. We present three patients with both domestic parasitic infections and asthma to raise awareness of the potential challenge of eosinophilia and to provide experience in the management of parasitic infections in the setting of planned or ongoing anti-IL5 treatment. One, a patient from Croatia with moderate asthma but severe blood eosinophilia had an underlying Strongyloides stercoralis infection, with positive stool cultures. Second, a patient with severe allergic asthma and gastrointestinal symptoms had a positive S. stercoralis titer in serology with a clinical response to treatment with ivermectin. Third, a patient with severe nonallergic eosinophilic asthma and eosinophilic granulomatosis with polyangiitis (EGPA) showed an increasing hepatic tumour under anti-IL5-receptor therapy. Positive serology confirmed the diagnosis of Echinococcus multilocularis, and albendazole therapy was initiated. Anti-IL5 therapies were safely started (Patient 2) or resumed (Patient 3) after the initiation of antiparasitic treatment. Screening for parasitic infections is useful in cases of hypereosinophilia, extrapulmonary symptoms or stay in endemic regions.