Candida auris has unprecedently emerged as a multidrug resistant fungal pathogen, considered a serious global threat due to its potential to cause nosocomial outbreaks and deep-seated infections with staggering transmissibility and mortality, that has put health authorities and institutions worldwide in check for more than a decade now. Due to its unique features not observed in other yeasts, it has been categorised as an urgent threat by the Centers for Disease Control and Prevention and other international agencies. Moreover, epidemiological alerts have been released in view of the increase of healthcare-associated C. auris outbreaks in the context of the COVID-19 pandemic. This review summarises the current evidence on C. auris since its first description, from virulence to treatment and outbreak control, and highlights the knowledge gaps and future directions for research efforts.

Ticks are obligatory hematophagous parasites that serve as vectors for a large amount of important human and livestock pathogens around the world, and their distribution and incidence of tick-associated diseases are currently increasing because of environmental biomass being modified by both climate change and other human activities. Hyalomma species are of major concern for public health, due to their important role as vectors of several diseases such as the Crimea–Congo hemorrhagic fever (CCHF) virus in humans or theileriosis in cattle. Characterizing the Hyalomma-associated microbiota and delving into the complex interactions between ticks and their bacterial endosymbionts for host survival, development, and pathogen transmission are fundamental, as it may provide new insights and spawn new paradigms to control tick-borne diseases. Francisella-like endosymbionts (FLEs) have recently gained importance, not only as a consequence of the public health concerns of the highly transmissible Francisella tularensis, but for the essential role of FLEs in tick homeostasis. In this comprehensive review, we discuss the growing importance of ticks associated with the genus Hyalomma, their associated tick-borne human and animal diseases in the era of climate change, as well as the role of the microbiome and the FLE in their ecology. We compile current evidence from around the world on FLEs in Hyalomma species and examine the impact of new molecular techniques in the study of tick microbiomes (both in research and in clinical practice). Lastly, we also discuss different endosymbiont-directed strategies for the control of tick populations and tick-borne diseases, providing insights into new evidence-based opportunities for the future.

Over 60% of emerging infectious diseases in humans are zoonotic, often originating from wild animals. This long-standing ecological phenomenon has accelerated due to human-induced environmental changes. Recent data show a significant increase in fungal infections, with 6.5 million cases annually leading to 3.7 million deaths, indicating their growing impact on global health. Despite the vast diversity of fungal species, only a few are known to infect humans and marine mammals. Fungal zoonoses, especially those involving marine mammals like cetaceans, are of global public health concern. Increased human–cetacean interactions, in both professional and recreational settings, pose risks for zoonotic disease transmission. This review focuses on the epidemiology, clinical manifestations, and zoonotic potential of major fungal pathogens shared in humans and cetaceans, highlighting their interspecies transmission capability and the challenges posed by antifungal resistance and environmental changes. It underscores the need for enhanced awareness and preventative measures in high-risk settings to protect public health and marine ecosystems.

Cetaceans, which are crucial in marine ecosystems, act as sentinels for ecosystem and human–environmental health. However, emerging fungal infections, particularly by Candida spp., pose a growing concern in these marine mammals. This review consolidates current knowledge on the prevalence, clinical manifestations, species distribution, and antifungal resistance of Candida infections in cetaceans. We detail the diverse pathogenic impacts of Candida, including respiratory, dermal, and systemic afflictions, underscoring diagnostic and treatment challenges amid rising antifungal resistance. Our analysis extends beyond health concerns in captive cetaceans, where confinement stress heightens vulnerability, to encompass substantial ecological risks in wild populations. The review emphasizes the One Health perspective, linking cetacean health with broader environmental and human public health issues. We particularly focus on the potential zoonotic transmission of emerging fungal pathogens such as Candida auris and the role of environmental changes in fostering antifungal resistance. The study underscores the need for concerted, interdisciplinary efforts in veterinary, medical, and environmental sciences to enhance understanding and management of Candida infections in cetaceans. We advocate for comprehensive monitoring and collaborative research initiatives to mitigate the rising challenge of these infections. Addressing Candida spp. in cetaceans is not just a conservation priority but a critical step in safeguarding overall marine health and, by extension, human health in the context of evolving infectious diseases.

Introduction: Immunoglobulin replacement therapy (IgRT), either intravenous (IVIg) or subcutaneous (SCIg), is crucial for managing primary immune deficiencies (PIDs) with hypogammaglobulinemia by reducing infection rates and mortality. During the COVID-19 pandemic, a global shortage of SCIg prompted our unit to reduce SCIg doses or maintain the same dose intravenously. This study evaluates the impact of a standardized SCIg dose reduction on infection rates and clinical outcomes in patients with humoral PID and with a low burden of infections.Methods: Adult PID patients on SCIg for at least 6 months, with IgG trough levels ≥ 700 mg/dL (or ≥ 900 mg/dL under specific conditions), and no significant infections in the past 6 months were eligible. A dose reduction of 15 mg/kg/week (60 mg/kg/month) for every 150 mg/dL above 700 mg/dL (or 900 mg/dL) was proposed. Clinical and laboratory data, and infectious events at 6- and 12-month follow-ups, were analyzed.Results: Thirty-one patients with PID were included: common variable immunodeficiency (54.83%), IgG subclass deficiency (9.67%), and other PIDs (35.48%). The average SCIg dose was initially reduced from 7.82 g/week to 5.72 g/week and adjusted to 6.94 g/week at 12 months. There was no significant change in severe or mild infections before and at 6- and 12-months post-dose adjustment. The dose reduction saved an average of 5,550 euros per patient annually, totaling 172,050 euros annually for our cohort.Discussion: Optimizing SCIg doses in selected well-controlled humoral PIDs is feasible without increasing infection rates, conserving this plasma-derived product during shortages. Larger prospective studies are needed to confirm this strategy's utility and its application to other Ig formulations.

The novel pathogen Candida auris has rapidly become a major health threat due to its high virulence, resistance to multiple antifungal agents, and remarkable environmental persistence. This study evaluated the influence of phenotypic traits and antifungal minimum inhibitory concentrations (MICs) on C. auris virulence using a Galleria mellonella infection model. Ten clinical strains, categorized as aggregative or non-aggregative, were analyzed for antifungal susceptibility and survival outcomes. All strains exhibited fluconazole resistance, with variable susceptibilities to other antifungals. Survival analysis revealed that the non-aggregative phenotype was independently associated with reduced survival in G. mellonella (HR = 2.418, p = 0.015), while antifungal MICs and invasive origin were not significant independent predictors of mortality in an elastic net-adjusted multivariable model. Strong correlations were observed between certain antifungal MICs, suggesting potential cross-resistance patterns; however, no independent association with virulence was identified. These results suggest that C. auris possesses not only an enhanced ability to develop antifungal resistance but also the capacity to do so without incurring fitness costs that could attenuate its virulence.