Emerging Human Health Problems Caused by Pathogenic and Immuno-activating Fungi

In recent years, several types of novel fungal health problems have been emerging in parallel. Antifungal-drug-resistant opportunistic pathogens have emerged both in previously unknown lineages, notably Candida auris, and in traditional pathogens and opportunists such as the Trichophyton mentagrophytes species complex and Aspergillus fumigatus. Emergence of resistance in Aspergillus is clearly connected to agricultural use of fungicides related to medical antifungals, but is brought into further prominence by the simultaneous emergence of immunosuppressive viral effects connected to influenza and SARS CoV 2 infections. The sources of drug resistance phenotypes in Candida auris and Trichophyton indotineae are unclear, but neither climate change nor drug misuse can be clearly implicated. In Onygenalean endemic mycoses, however, climate change is under suspicion of causing range extension in Coccidioides immitis. Decimation of some North American bat species associated with Histoplasma hot spots has not had a perceptible effect on this fungus so far. Historical reading suggests that it may have survived a previous loss of conditioned habitat when the passenger pigeon became extinct. Emergence of Emergomyces and new Blastomyces species appears mainly to be related to enhanced recognition. Two separate sporotrichosis outbreaks in cats in South America and Southeast Asia suggest a little-discussed mechanism of pathogen emergence, opportunity trawling, i.e. ingress of new potential hosts into pathogen habitats leading to novel epizootics. In the investigations of non-pathogenic fungi connected to immunologically or toxicologically mediated symptomatology in indoor environments, the slow augmentation of difficult-to-obtain evidence has clarified that indoor dampness and mould can cause diverse health effects, ranging from novel advent of asthmatic conditions to eczema-like skin disturbances. The methodology used to evaluate indoor mould symptomatology shares some of the deficiencies that racked medical evaluations of causality during the SARS CoV 2 outbreak. Pertinent epidemiological connections may be obscured by an excessive positivistic demand for proof where the combination of valid evidence and judicious attention to the precautionary principle would better serve the community.