Some like it hot: the emergence of Candida auris from a One Health lens

Abstract

Candida auris is an emergent fungal pathogen of critical public health concern due to its multi-drug resistance, high transmissibility, environmental persistence, and capacity to cause invasive infections with elevated mortality rates, especially in intensive care outbreaks. Since its first identification in 2009, the near-simultaneous emergence of six genetically distant clades across multiple continents without clear close phylogenetic links suggests a novel evolutionary trajectory. This unusual phylogeographic distribution, combined with remarkable thermotolerance, halotolerance, and antifungal resistance, has led to the hypothesis that C. auris is a sentinel species for climatedriven fungal emergence. Experimental data have demonstrated that C. auris can grow at higher temperatures and in saline environments compared to its close relatives, suggesting adaptation to increasingly warm ecological niches. Environmental isolates from undisturbed mangrove sediments in regions without clinical cases exhibit lower thermotolerance and antifungal resistance than clinical strains, supporting an evolutionary trajectory from an environmental saprobe to a human pathogen. Furthermore, its recovery from diverse animal hosts, including dogs, reptiles, and amphibians, in areas lacking documented human transmission raises the possibility of a zoonotic/zooanthroponotic or sapronotic component in its emergence. The widespread detection of C. auris in wastewater, effluents, agricultural settings, and polluted environments further implies ecological persistence and possible selection of resistant strains through exposure to fungicidal residues from agricultural and industrial sources. This convergence of complex ecological, climatic, and anthropogenic factors underlines the importance of elucidating the mechanisms of C. auris emergence and dissemination. Understanding its evolutionary ecology is essential for predicting future hotspots of emergence, improving surveillance, and designing effective multidisciplinary control strategies against outbreaks. A One Health perspective, integrating human, animal, and environmental health, is fundamental to address the complex dynamics driving the rise of C. auris and mitigate the threat of future climate-linked fungal pathogens