A Fungal Spore Calendar for England: Analysis of 13 years of Daily Concentrations at Leicester, UK

Abstract

BackgroundFungal respiratory allergy is believed to affect up to 30% of hayfever sufferers and up to 70% of severe asthmatics in the UK, however trends in fungal spore seasonality are not well described. Information about seasonal trends would help allergists determine sources of fungal sensitisation and aid disease management.MethodDaily monitoring was carried out at Leicester from 2007 to 2020 using a Burkard volumetric spore trap. Fungal spore concentrations were analysed by microscopy, identifying 23 morphologically distinct taxa. Daily average concentrations were calculated as spores/m3of air sampled and a 90% method used to determine the spore seasons.ResultsThirteen years of data were used to develop a fungal spore calendar for the nine most abundant spore types identified;Alternaria, Cladosporium, Didymella, Leptosphaeria, Sporobolomyces, TilletiopsisandUstilagoplus the wider groupings ofAspergillus/Penicilliumtype and coloured basidiospores. All have been implicated in fungal allergy.We observed long seasons for,Cladosporium, SporobolomycesandTilletiopsis, beginning in late spring and ending in late autumn. In contrastUstilagoand the highly allergenicAlternariashowed relatively short seasons, spanning summer and early autumn. Temperature and precipitation were the main meteorological factors related to spore concentration with wind speed appearing to have little influence. Over the study period, there was a reducing trend for total spore concentrations, driven by a reduction in “wet weather” spores, in line with a reduction in precipitation. Conversely, the “dry weather” spores ofAlternariaandCladosporiumdemonstrated an increasing trend.ConclusionWe present an aeroallergen calendar to provide readily accessible information to patients, healthcare professionals and pharmaceutical companies on exposure concentrations over the year in central England and potentially more widely across the UK. More research on allergenic thresholds would enhance the clinical usefulness of aeroallergen calendars.