Fungal Zoonotic Infections in Fish an emerging threat to Aquatic and Terrestrial life

Abstract

Fish fungal infections represent an emerging threat with important implications for both animal and human health. Several primary fish pathogens have zoonotic potential, underscoring the relevance of fish mycoses for public health issues globally. Fungal pathogens of free-living and farmed fish are ubiquitous in aquatic environments. They cause superficial to disseminated infections and play a significant role in morbidity and mortality events in cultured and wild fish stocks. Although most published cases of fungal infections in fish refer to opportunistic pathogens that take advantage of compromised host immunity to invade the host, some fungi can behave as primary pathogens, able to cause disease even in apparently immunocompetent fish. The genera with the greatest number of pathogenic species for fish include Aphanomyces, Aspergillus, Candida, Chrysosporium, Exophiala, Fusarium, Ichthyophonus, Paecilomyces, Penicillium, Phoma, Saprolegnia, Trichophyton, and Trichosporon although zoonotic species are described mainly within genera Chrysosporium, Histoplasma, Paracoccidioides, Sporothrix or Cryptococcus. Yeasts play a role in algun pseudomycoses and mycoses. Saprolegniasis, epizootic ulcerative syndrome, branchiomycosis and dermal pseudomycoses are some examples of emerging fungal infectious diseases causing morbidity and mortality in farmed fish and amphibians and economic losses to aquaculture. This chapter examines the incidence and distribution of clinically relevant fungi in fish hosts, pathological findings associated with infection, and present knowledge on transmission routes. Challenges related to therapy and preventive strategies are discussed. Finally, the zoonotic potential and possible implications for public health will be addressed.