D1.84 - Invasion Meets Allergy: Cortaderia selloana as an Emerging Grass Aeroallergen

Cortaderia selloana (pampas grass; CS) is a South American plant rapidly invading Western Europe and other regions, particularly urban and degraded areas. Climate change models predict further spread in the coming decades. While the ecological impact of invasive plants is well recognised, their role in respiratory allergy remains largely disregarded. We previously reported high sensitisation rates to CS pollen in a pilot cohort of grass-allergic patients in the highly invaded Cantabria region (Northern Spain). An additional concern is that CS pollinates in late August-September, up to three months later than local grasses, when native pollen is absent.

We are now conducting a multicentric study, by comparing adult and paediatric patients from two highly invaded coastal regions and two inland, non-invaded regions, including a paediatric population. Here we studied a total of 229 patients: 163 from Cantabria (55 children) and 69 from the inland non-invaded region of Burgos (18 children). Fifty-one non–grass-allergic patients served as controls. Serological analyses were performed using a prototype ImmunoCAP-CS for research use only test. 

In the invaded region, 94% of Phleum pratense (PhP)-positive patients were also positive for CS (97% adults, 91% children; 93% men and 97% women). Notably, a proportion of CS-exposed, PhP-negative patients were positive for CS. 65% of the CS positive cohort reported symptoms in August-September. In the inland non-exposed cohort, 100% concordant sensitisation to PhP and CS was observed in positive and negative patients, with no isolated CS sensitisation detected.

Most patients allergic to grass pollen in invaded regions are sensitised to CS. Given that 20–30% of the population suffers from grass allergy and that CS flowers months later than the local grasses, its expansion may significantly increase disease burden and prolong the allergy season. These findings highlight the potential impact of invasive plant species on human allergy and the need for standardised diagnostic extracts, implementation of specific IgE assays and epidemiological surveillance. They also urge consideration of CS within the European invasive species regulatory frameworks to mitigate its emerging impact in public health.