Global Warming Will Bring New Fungal Diseases for Mammals

Abstract

Fungi are major pathogens of plants, other fungi, rotifers, insects, and amphibians, but relatively few cause disease in mammals. Fungi became important human pathogens only in the late 20th century, primarily in hosts with impaired immunity as a consequence of medical interventions or HIV infection. The relatively high resistance of mammals has been attributed to a combination of a complex immune system and endothermy. Mammals maintain high body temperatures relative to environmental temperatures, creating a thermally restrictive ambient for the majority of fungi. According to this view, protection given by endothermy requires a temperature gradient between those of mammals and the environment. We hypothesize that global warming will increase the prevalence of fungal diseases in mammals by two mechanisms: (i) increasing the geographic range of currently pathogenic species and (ii) selecting for adaptive thermotolerance for species with significant pathogenic potential but currently not pathogenic by virtue of being restricted by mammalian temperatures.

ANaganishiain high places: functioning populations or dormant cells from the atmosphere?

“…To our knowledge, this is the first demonstration of the growth of any microbe during extreme freeze-thaw cycles, although activity of microbes during such cycles has long been known (reviewed in Schmidt et al 2009a). The ability to survive and thrive within a very broad temperature range may be a characteristic widespread within the Tremellomycetes; even pathogenic Cryptococcus gatti and C. neoformans exhibit broad tolerance to a range of temperatures (Nichols et al 2007, Garcia-Solache and Casadevall 2010), but have not been shown to be able to grow at subfreezing or fluctuating temperatures like members of the genus Naganishia .…”

Phagocytosis ofCryptococcus neoformansby, and Nonlytic Exocytosis from,Acanthamoeba castellanii

“…Additional evidence for this concept comes from studies of insect fungal pathogens, which suggest that the capacity for insect pathogenicity may follow preadaptation from interactions with amoebae in the environment (4). Understanding the mechanisms by which virulence emerges in environmental microbes is important considering that global warming has been hypothesized to bring about new fungal diseases in the coming century (13).…”

Stop neglecting fungi

“…However, infections of otherwise healthy people are on the rise. Global warming is inducing rapid poleward movement of crop fungal pathogens, and may also increase the prevalence of fungal disease in humans as fungi adapt to survival in warmer temperatures 4 . In this scenario, increasing resistance to the limited arsenal of antifungal drugs is a serious concern 5 , especially for Candida and Aspergillus infections, for which the therapeutic options have become limited.…”