Impact of climate change and natural disasters on fungal infections

Seasonal cycles of infectious diseases have been variously attributed to changes in atmospheric conditions, the prevalence or virulence of the pathogen, or the behavior of the host. Some observations about seasonality are difficult to reconcile with these explanations. These include the simultaneous appearance of outbreaks across widespread geographic regions of the same latitude; the detection of pathogens in the off-season without epidemic spread; and the consistency of seasonal changes, despite wide variations in weather and human behavior. In contrast, an increase in susceptibility of the host population, perhaps linked to the annual light/dark cycle and mediated by the pattern of melatonin secretion, might account for many heretofore unexplained features of infectious disease seasonality. Ample evidence indicates that photoperiod-driven physiologic changes are typical in mammalian species, including some in humans. If such physiologic changes underlie human resistance to infectious diseases for large portions of the year and the changes can be identified and modified, the therapeutic and preventive implications may be considerable.

There is limited information on the public health impact of wildfires. The relationship of cardiorespiratory hospital admissions (n = 40 856) to wildfire-related particulate matter (PM(2.5)) during catastrophic wildfires in southern California in October 2003 was evaluated. Zip code level PM(2.5) concentrations were estimated using spatial interpolations from measured PM(2.5), light extinction, meteorological conditions, and smoke information from MODIS satellite images at 250 m resolution. Generalised estimating equations for Poisson data were used to assess the relationship between daily admissions and PM(2.5), adjusted for weather, fungal spores (associated with asthma), weekend, zip code-level population and sociodemographics. Associations of 2-day average PM(2.5) with respiratory admissions were stronger during than before or after the fires. Average increases of 70 microg/m(3) PM(2.5) during heavy smoke conditions compared with PM(2.5) in the pre-wildfire period were associated with 34% increases in asthma admissions. The strongest wildfire-related PM(2.5) associations were for people ages 65-99 years (10.1% increase per 10 microg/m(3) PM(2.5), 95% CI 3.0% to 17.8%) and ages 0-4 years (8.3%, 95% CI 2.2% to 14.9%) followed by ages 20-64 years (4.1%, 95% CI -0.5% to 9.0%). There were no PM(2.5)-asthma associations in children ages 5-18 years, although their admission rates significantly increased after the fires. Per 10 microg/m(3) wildfire-related PM(2.5), acute bronchitis admissions across all ages increased by 9.6% (95% CI 1.8% to 17.9%), chronic obstructive pulmonary disease admissions for ages 20-64 years by 6.9% (95% CI 0.9% to 13.1%), and pneumonia admissions for ages 5-18 years by 6.4% (95% CI -1.0% to 14.2%). Acute bronchitis and pneumonia admissions also increased after the fires. There was limited evidence of a small impact of wildfire-related PM(2.5) on cardiovascular admissions. Wildfire-related PM(2.5) led to increased respiratory hospital admissions, especially asthma, suggesting that better preventive measures are required to reduce morbidity among vulnerable populations.

Melanins are ancient biological pigments found in all kingdoms of life. In fungi, their role in microbial pathogenesis is well established; however, these complex biomolecules also confer upon fungal microorganisms the faculty to tolerate extreme environments such as the Earth’s poles, the International Space Station and places contaminated by toxic metals and ionizing radiation. A remarkable property of melanin is its capacity to interact with a wide range of electromagnetic radiation frequencies, functioning as a protecting and energy harvesting pigment. Other roles of fungal melanin include scavenging of free radical, thermo-tolerance, metal ion sequestration, cell development, and mechanical-chemical cellular strength. In this review, we explore the various functions ascribed to this biological pigment in fungi and its remarkable physicochemical properties. Functions of fungal melanin. Fungal melanins play multiple biological functions including photoprotection, energy harvest and thermoregulation by readily absorbing and transducing electromagnetic radiation. Fungal melanins also function in free radical and metal binding; protection against dehydration, chemical and mechanical stressors; and fungal development and conidiation.