What Can We Do To Address the Threat of Fungal Superbugs Tied to Climate Change?

Climate change may soon come with another dangerous side effect: possibly deadly fungal infections. Scientists fear that disease-causing strains of aspergillus, coccidioides (which causes Valley Fever) and other fungi could soon be on the move thanks to changing weather patterns. As their ranges expand, so does the risk of difficult-to-diagnose and drug-resistant infections.

Those in warm and arid climates like the Southwestern United States, Mexico and Central America are likely familiar with Valley Fever. This lung infection is caused by breathing in spores of the coccidioides fungi, which grow in dry soils and are kicked up with dust. It presents with flu-like symptoms such as fever and cough, and while most people fully recover, around 5 to 10 percent of those infected develop serious long-term lung problems. In rare cases, the infection can spread to other parts of the body, like the skin or brain. Other fungal infections include aspergillosis, caused by spores from mold species that live almost everywhere and impacting primarily immunocompromised people.

But what does climate change have to do with fungus? Moisture and temperature have a direct impact on fungi’s ability to reproduce, explains Kathleen Treseder, professor of ecology and evolutionary biology at the University of California, Irvine.

“In the case of some fungal diseases like Valley Fever, the fungi do better at hotter, drier climate conditions,” she told TriplePundit. “As climate change is pushing ecosystems in that direction, the fungi do better.”

Within the U.S., Valley Fever is endemic to the Southwest and drier areas of the Pacific Northwest, but it could move into the plains across states like Kansas and Nebraska, reaching as far north as the border with Canada, as temperatures rise and droughts expand, Treseder said.

Likewise, other fungi such as aspergillus mold species that are adapted to wetter conditions could reproduce faster — and cause more infections — in areas that are experiencing heavier rainfall due to climate change. Treseder compared this to what’s happening with the mosquito-borne West Nile Virus, which is expected to infect more people with changing weather conditions.

If the fungus that causes Valley Fever spreads to new regions, it could be a big problem for people who haven’t been exposed to it before and therefore don’t have any immunity, Treseder said. “They're particularly vulnerable to the disease.” 

While it is not usually fatal, the longer it goes untreated, the more likely it is to cause severe illness including disfigurement and even death. And fungal infections like Valley Fever aren’t easy or cheap to treat, with treatment for individual cases costing upwards of $30,000, she said. 

“It's really hard to get rid of Valley Fever once you've got it, because fungi are actually pretty closely related to humans,” Treseder continued. “Any treatment we have identified to kill off the fungi also harms our own cells. People have likened it to getting chemotherapy — the treatment is almost worse than the cure in some cases.”

The disease also poses a huge risk to mammals, especially pets. “Dogs get Valley Fever,” she said. “And it's fatal for them very frequently.”

For Southwestern U.S. states, the first line of defense is mandatory reporting of disease cases. This gives medical professionals and scientists a heads up at the start of an outbreak, which helps them identify new infections faster, Treseder said. That’s why scientists are asking the U.S. Centers for Disease Control and Prevention (CDC) to roll out mandatory reporting to states where infectious fungi are expected to spread.

Another important measure is knowing ahead of time when and where outbreaks are likely to occur, which is now possible from looking at what climate conditions are expected for a given year, Treseder said. If an outbreak is expected, the CDC can forewarn hospitals and doctors to be vigilant. This could be especially useful in areas new to a particular fungus, as misdiagnosis is more common when medical professionals are unfamiliar with the illness it can cause.

“I'm really glad now we have an approach where we can predict the future trajectory of fungal diseases,” she said. “Any sort of early warning or time to prepare can be very helpful to us and our pets.”

For people living in areas where Valley Fever is established or spreading, the best prevention is to curtail the amount of dust stirred up with outdoor activities. That means wetting down fields and soil prior to activities like sporting events and gardening, she said.

There aren’t any antifungal vaccines available that could help mitigate the spread of fungi, but there are some in the works. For example, the University of Arizona is in the process of developing Valley Fever vaccines for people and dogs.

“It's hard to stop the fungus from moving around. I wish that we could,” Treseder said. “Ultimately, the only real way to fight it is to fight climate change.”

In the meantime, the best solution is to predict and stay on top of outbreaks so public agencies and medical professionals can be educated on the threat of new fungal infections as they spread. That way, they’ll know what to look for and how to treat it early on.