Introduction: Between 5-10% of asthmatics have severe disease and many require commencement of anti-eosinophilic biologics. Eosinophils play a pivotal role in host defence against parasite infections and thus prescribers of anti-IL5/5R biologics are cautioned against their use in patients with known or untreated helminth infections. There remains global ambiguity surrounding if, when and how, patients should be screened for this risk.

Methods: A retrospective review of a protocol directed parasite screen performed from January 2019 upto January 2023 in at-risk, pre anti-IL5/5R biologic severe asthma patients was completed. Stool smear testing and serum enzyme-linked immunosorbent assays (ELISA) were used to detect parasitic antibodies.

Results: A total of 479 patients were screened for parasite infection. 26 patients (5.4%) had true positive result and of these, 16 (61.5%) were for Schistosoma and 10 (38.5%) for Strongyloides. Table 1 stratifies the characteristics of these patients. No patient had a positive stool smear, or Toxocara and Filaria antibodies.

Conclusions: Within a targeted population of at-risk severe eosinophilic asthma patients, just under 1 in 20 patients had a positive parasite screen. To date, this is the largest reported cohort of severe asthmatics to have undergone pre-anti-IL5/5R screening in the literature which serves to help inform global clinical practice and pre-biologic risk assessments.