Scientists have discovered a deadly, drug-resistant fungus hiding in common gardening soils, composts and flower bulbs. 

A team of researchers tested these gardening products for a drug-resistant strain of aspergillus fumigatus, a type of infectious fungus previously only found in Europe.

They found levels high enough to infect gardeners with compromised immune systems, such as people with lung disease or actively undergoing chemotherapy. 

When inhaled, A. fumigatus can grow inside the lungs and cause an infection called aspergillosis. 

A. fumigatus is typically treatable with antifungal medication. But a strain that is resistant to treatment has been been spreading throughout Europe. 

Now, it appears to have emerged in the US. 

Research has shown that A. fumigatus causes over 300,000 globally each year with mortality rates of 30 percent to 90 percent.

In immunocompromised patients, it has nearly 100 percent fatality rate without treatment or if the infection is resistant to antifungal drugs. 

Symptoms include fever, coughing up blood or plugs of mucous, and worsening asthma, according to Mayo clinic.

But 'if you have a healthy immune system, it’s not an issue,' Dr Michael Mansour, an infectious disease expert at Massachusetts General Hospital who treats immunocompromised patients, told the Boston Globe.

'Our immune cells will gobble them up,' he said. 

The University of Georgia researchers collected 525 samples from soil, compost, flower bulbs and other plant products that came from farms across the US.

They tested each sample for the drug-resistant strain of A. fumigatus, and 24 tested positive.  

The study did not determine which types of compost were most likely to contain the drug-resistant strain, nor which commercial sources are most likely to sell it. 

But the results suggest that levels are especially high on imported flower bulbs. 

The rise of drug-resistant A. fumigatus is likely driven by widespread agricultural use of antifungals to kill crop diseases, the researchers stated in their report.

But more research is needed to determine how widespread this fungal disease is in the US, and identify hotspots where it's most prevalent. 

People with compromised immune systems should take caution and wear a mask and gloves when gardening to protect themselves from spores, experts warn. 

A. fumigatus breaks down organic matter, which is why it's commonly found in compost and leaf piles where it thrives in the heat produced by decomposition.

Many people who regularly garden inhale it every day, as gardening disturbs the soil and releases the spores into the air. 

'It’s pretty much everywhere in the environment,' study author Marin Talbot Brewer, a professor of mycology and plant pathology at the University of Georgia, told the Boston Globe. 

This has been known to cause problems for immunocompromised people, which include those with lung disease and chronic obstructive pulmonary disease, recent organ transplant recipients and patients undergoing chemotherapy.

In these populations, aspergillosis can spread rapidly from the lungs to the brain, heart, kidneys or skin, and may be fatal, according to Mayo clinic. 

Mansour told the Boston Globe that this infection is common among his patients, but typically occurs in those who garden regularly and do not take precautions like wearing a mask and gloves.

He has also seen cases in those who participated in a renovation project involving dampness recently.

Most of these cases have been responsive to treatment, he said. 

Previous studies confirmed that drug-resistant A. fumigatus was present in agricultural materials. 

But the University of Georgia study is the first to test whether this fungal disease could be spreading through retail plant and gardening products in the US.