Fungal diversity in Sahara dust: Aspergillus sydowii and other opportunistic pathogens

The Caribbean is influenced by Sahara Dust Storms (SDS) every year. SDS can transport a diversity of microorganisms, including potential pathogens of humans, animals, and plants. In fact, SDS have been suggested as a source of Aspergillus sydowii, reported to cause aspergillosis disease in gorgonian sea fans. However, the diversity of fungal spores in SDS remains unknown and there are conflicting studies as to whether A. sydowii spore are capable of crossing the Atlantic Ocean. In this study, we estimated the fungal diversity of the Saharan dust trapped on air filters during five days of a ship’s trajectory in the eastern Atlantic during a dust event. Also, we investigated whether SDS is a potential source of opportunistic fungal pathogens. We isolated 30 morphospecies including the ascomycetes Aspergillus (33% of identified isolates), Thielavia (18%), Penicillium (12%), Chaetomium strumarium (3%), Periconia (2%), and Cladosporium sphaerospermum (1%). Many of these groups include opportunistic pathogens. Species diversity was similar across days but with significant differences between Days 3 vs 5 and between hazy vs clear days. We report for the first time that Thielavia, Chaetomium strumarium and Periconia are present in SDS and are capable of surviving long-distance transport in SDS. The presence of A. sydowii isolates is consistent with reports of SDS as a source of inoculum for sea fan aspergillosis. This could signify that SDS are carriers of viable, potentially pathogenic spores which can be deposited on terrestrial or aquatic substrates.