Fungal infections become more common as their ranges expand

Research indicates that fungal infections are more common than doctors or patients realise. It is expected to grow even more in the coming years.

“We’re definitely seeing disease in locations we haven’t seen before,” said Dr. George Thompson, an infectious disease specialist at the University of California, Davis. “And it’s worrying, because if we do learn about those locations, where are the places where they occur that haven’t been fully identified yet?”

Thompson co-authored an article published Monday in Annals of Internal Medicine, which notes that more than 10% of fungal infections are diagnosed outside areas where pathogens are known to be endemic. In addition, the paper says, misdiagnoses and a lack of data make it difficult to know how common the cases really are.

This is becoming an even more pressing problem, as research shows that climate change is making this infection more prevalent. For example, the fungus that causes valley fever thrives in desert climates, so the increased heat and drought created more areas hospitable for its growth.

Desert landscape, Sedona, Arizona, 2009.
Sedona, Arizona, 2009. Carol M. Highsmith/Getty Images file

Meanwhile, the fungus Histoplasma, which can cause illness characterized by fever, cough, and fatigue, tends to survive longer in high humidity—a condition that becomes more common as temperatures rise. Furthermore, histoplasma are found in soils that contain large amounts of bird and bat droppings, and climate change is altering the migration patterns of some of these species.

People generally get fungal infections after inhaling the spores. Often, the immune system fights off these invaders, or the infection results in mild, flu-like symptoms that resolve on their own. But some people — usually those with weakened immune systems — can develop life-threatening illnesses such as pneumonia or meningitis.

“The vast majority of people who get valley fever will tell you they’ve had a cough that lasts for a few weeks and goes away,” said Dr. Arturo Casadevall, a microbiologist and immunologist at Johns Hopkins University School of Medicine. “But when people are immunosuppressed or when they have bad luck because they got too much of a dose, these diseases can spread or exit the lung.”

Typically, different fungal infections are associated with specific regions: Valley fever is more common in the Southwest, for example, while histoplasmosis is identified mostly in the central and eastern states. But the coccidia fungus was found in Washington soil in 2014.

Thompson’s paper came just weeks after another study revealed high rates of fungal disease diagnoses far beyond traditionally understood geographic areas. The researchers found that 94% of US states have at least one county with a high number of histoplasmosis cases, and 69% have at least one county with a high number of Valley Fever cases.

“Over the past few years, I’ve started getting a lot of requests for help with these diseases,” said Andrej Spec, a co-author of that paper and an infectious disease specialist at Washington University School of Medicine in St. Louis. . “I often get a request that starts with, ‘Interestingly, we don’t have this disease in Massachusetts. But this patient has never flown in from Massachusetts and he has it, very funny thing. But I’m like, ‘You already have; It’s just that the maps are no longer updated.”

The last study to update the geographic distributions of pathogenic fungi in the United States based on patient data was in 1969, according to the SPICE study.

Globally, an analysis conducted in 2019 identified that fungal infections are on the rise and suggested that fungi may be commonly overlooked as sources of infection. A World Health Organization report in October also found that severe fungal infections became more common among people with pre-existing health problems during the Covid pandemic.

Climate change isn’t the only potential factor fueling this trend, Casadevall said. Increased travel to places where fungal infections are common could play a role, and doctors may get better at diagnosing infections where they weren’t detected before.

But Casadevall said that many U.S. hospitals do not report fungal infections to the CDC, and that historically the agency has not prioritized collecting this data because fungi generally do not cause outbreaks. The CDC received more than 20,000 reports of Valley Fever and nearly 1,100 reports of confirmed or probable histoplasmosis in 2019.

Thompson and other infectious disease experts have called for national surveillance of fungal infections and are urging doctors to test for them more often.

Fungal infections are not easily identifiable in routine tests, so if doctors are not aware that this could be a risk, they may not order the appropriate tests. The later a diagnosis is made, the longer it takes to treat a patient, which can lead to higher medical costs and an increased chance of serious illness or death. In some cases, a fungal infection can take months of treatment to clear up and may become chronic.

Some rapid tests allow doctors to diagnose fungal infections within hours or minutes, but they are not widely available in the United States (the standard way to test is to send a sample), said Dr. David Denning, CEO of Global Action for Fungal Infection, a research and advocacy group. of urine or blood to the lab, then wait several days for the result.)

“There are very few molecular tests for fungi that have been approved by the Food and Drug Administration,” Denning said. “The FDA rules are very strict, and that’s a good thing, but it’s also a bad thing because all of Europe is using these tests and in the United States there are a lot of barriers to adopting these tests on a routine basis.”

Many people are never diagnosed, Thompson said: “There are likely to be a large number of patients who were never directly diagnosed and who actually experienced a lot of morbidity with their disease.”

Leave a Reply

%d bloggers like this: