Berkeley Public Health launches major study on effects of climate change and social inequality on deadly fungal infections

Most people think of fungi as the mushrooms that pop up in backyard gardens, the tasty morels on gourmet menus, and the yeasts used to make beer. But they also include some of the most deadly pathogens affecting vulnerable populations globally.

Fungal pathogens cause over a billion human infections—and an estimated 1.6 million deaths—every year. Concern over pathogenic fungi is rising as novel pathogens emerge, antifungal drug resistance rises sharply, and climate change threatens to increase infections and deaths from fungal diseases in the coming decades.

Now, a team of researchers at multiple institutions led by UC Berkeley School of Public Health Professor Justin Remais, chair of the Division of Environmental Health Sciences, is launching a major study using big data to understand where fungal diseases are emerging across the U.S., and how a changing climate will affect their spread. The research—funded by a $3.9 million, five-year grant from the National Institutes of Health (NIH)—will be critical to understanding this emerging threat to the health of high-risk groups in the coming decades.

Many fungal pathogens—such as Coccidioides, Histoplasma, and Aspergillus—live in the environment, such as in soils or decomposing leaves. People become infected when they inhale fungal spores or come into contact with fungal filaments called hyphae.

Researchers know that fungal diseases respond to shifts in weather and climate. Valley fever, for instance, is spread with airborne dust that blows from desert soils containing Coccidioides pathogens and is sensitive to drought and temperature changes in California and other western states. Similarly, histoplasmosis—a disease caused by the pathogen Histoplasma often found in bird and bat droppings—responds to light, humidity, and temperature changes. Coccidioides and Histoplasma typically cause flu- or pneumonia-like symptoms, such as fatigue, fever, and coughing. Still, they can cause severe and fatal “disseminated” infections if the fungus spreads from the lungs to other organs.

“Fungal disease risks are rising, and climate change may be playing a role, but we badly need improved data and new analytical approaches to predict how climate change will affect these diseases in the years to come,” said Dr. Remais. “Discovering how environmental changes are driving shifts in fungal disease will allow us to anticipate and respond to future risks, increase doctor and patient awareness, and ensure protective measures are made available to those most vulnerable to the impacts of climate change.”

Some fungal pathogens infect people during extreme weather events such as floods and hurricanes. For example, Mucormycetes can cause severe skin and wound infections among those who experience traumatic injuries during extreme weather. As storm surges and other climate extremes increase in intensity or frequency, the incidence of such infections may also increase.

“In order to estimate how these diseases will spread in the future, we need to examine how they have responded to previous weather extremes, then use models to explore how they will act in response to shifts in climate conditions and the frequency of extreme events as the planet warms,” said Remais.

The researchers will analyze more than one billion electronic medical records collected from nearly 100 million patients across the United States to study where fungal diseases are emerging and identify factors leading to disparities in fungal disease incidence and severity across vulnerable populations, investigating why socially and economically disadvantaged populations face greater risk.

“We will examine whether housing quality, social resilience, and FEMA assistance may protect against fungal outbreaks during natural disasters to better understand how communities can adapt and build resilience to fungal disease risks,” said Remais. “We also need to know more about the role of disparities in quality and timeliness of care, variation in population exposure to fungal pathogens, differences in susceptibility to infection and severe disease, preexisting conditions, immunosuppressive treatments, and substance use.”

The team at Berkeley includes experts in fungal biology, epidemiology, and biostatistics, as well as those with expertise in characterizing the climate drivers of infectious diseases. Berkeley researchers will develop data-adaptive statistical models and counterfactuals to estimate the proportion of fungal disease burden attributable to anthropogenic climate change, and will project the distribution of fungal diseases 30 to 50 years in the future. Collaborators at partner institutions bring expertise in the design and function of electronic health records systems and medical mycology.

“Analyzing this remarkable, vast dataset and integrating it with socioeconomic and climate information will help us understand how and why the risk of fungal diseases has been changing, identify areas at particularly high risk for an emergence or intensification of fungal diseases, and help health practitioners to better predict, detect, and prevent future infections,” Remais said.