Aspergillus: The Most Dangerous Cannabis Pathogen

Despite its classification as a schedule one controlled substance, medicinal cannabis has proven to be a successful treatment for a wide variety of medical conditions. It’s medicinal properties have shown great efficacy in treating the symptoms of neuropathic pain, muscle spasms, epilepsy, bipolar disorder, and the debilitating nausea that can be a result of chemotherapy and other cancer treatments. Despite the plant’s considerable medicinal benefits, there are potential consequences for patients who use medicinal cannabis which comes in the form of harmful bacteria and spores that can grow on the plant; some of which cultivators and dispensaries aren’t testing their product for. The most concerning of these fungi is Aspergillus.

While it’s been shown that there have been no overdoses from medicinal cannabis in the 33 states that have legalized its use, there have been documented cases of medicinal cannabis patients who have died from aspergillosis, a condition caused by inhaling Aspergillus spores.

What is Aspergillus?

Aspergillus is a saprophytic fungus that helps remove environmental carbon and nitrogen from the earth’s atmosphere. Aspergillus is most commonly found in the soil around us, where it thrives on naturally occurring organic debris. While Aspergillus predominantly grows underground, its spores propagate rapidly in the air with each fungus capable of producing thousands of conidia. These spores are commonly spread through environmental disturbances and strong air currents, that allow them to be found both indoors and out. Aspergillus spores are tiny, even by biological standards, allowing them to travel great distances in the air.

These spores are everywhere, and there’s a solid chance that you and I breathe in hundreds of them each and every day. While there is usually no risk for healthy individuals, Aspergillus is especially dangerous to immunocompromised individuals, in whom the airborne spores can lead to a debilitating invasive infection, called aspergillosis, that oftentimes proves to be fatal.

Who is at risk?

Those with compromised immune systems, either through disease or medical treatment, are at serious risk of developing an aspergillosis infection. A 1992 study found the incidence of cases of aspergillosis per year to be 1 – 2 patients per 100,000 people; however, this number is likely much higher today due to the increased use of immunosuppressants and stem cell therapy. There are a variety of factors that can increase an individual’s likelihood of developing aspergillosis including, but not limited to:

  • the ingestion of immunosuppressive drugs (after undergoing bone or organ transplants)
  • a low white blood cell count (resulting from chemotherapy)
  • asthma or cystic fibrosis
  • long-term corticosteroid therapy

For these individuals, aspergillosis begins when the spores are inhaled through the mouth where the fungus finds ample breeding opportunity in the lungs that can quickly lead to infection. Once the infection takes hold it can cause serious, and sometimes fatal, bleeding in the lungs. Additionally, due to the invasive nature of the infection, aspergillosis can quickly spread to a patient’s kidneys, heart, and even the brain. Aspergillosis is capable of spreading impressively fast and typically results in death, with little regard for how early the infection is observed by medical professionals. A large study conducted with people who had contracted invasive aspergillosis from organ and stem cell transplants found the one-year rate of survival for these patients to be 59% and 25% respectively.

Due to the increased risk of contracting aspergillosis via organ transplant, some transplant programs have removed patients who use cannabis from their donor waiting list. Cancer patients undergoing chemotherapy and other radiation treatments are also at an increased risk.

Though rare, there have been documented cases of otherwise healthy individuals developing an aspergillosis infection. The most recent case happened in 2016 and occurred in a cannabis user.

Do all cannabis products pose this risk?

The danger posed to medicinal cannabis patients exists solely through the practice of ingesting cannabis by smoking, and inhaling, the product directly into the lungs through combustion. This danger is due to the fact that the heat created through the combustion does not reach the approximately 200 degrees required to effectively eliminate Aspergillus spores. When these spores are present in the plant and smoked they are inhaled directly into the lungs where they pose a serious risk of infection.

Luckily for patients, there are methods of consuming medicinal cannabis that eliminate the risk of developing aspergillosis. Medical cannabis in edible or injestible form typically is not a concern because the stomach is not a suitable environment for Aspergillus to live and thrive.

Who tests for Aspergillus?

The following states require testing cannabis for Aspergillus (updated June 2020):

  • Alaska – A. flavusA. fumigatus, and A. niger
  • California – A. flavusA. fumigatusA. niger, and A. terreus
  • Michigan – A. flavusA. fumigatusA. niger, and A. terreus
  • Nevada – A. flavusA. fumigatusA. niger, and A. terreus
  • New York – Aspergillus species

In May 2020, the United States Pharmacopeia (USP)  published a scientific paper with recommendations for cannabis testing in the Journal of Natural Productswhich included A. flavus, A. fumigatus, A. niger, and A. terreus. It’s likely that regualtory bodies will use that recommendation to inform their testing requirements.

Medicinal Genomics can help labs test for Aspergillus flavusAspergillus fumigatusAspergillus niger, and Aspergillus terreus using our PathoSEEK® Microbial Safety Testing Platform. Data from our peer-reviewed study shows that qPCR-based testing for Aspergillus is far more accurate than culture-based methods. The USP agrees, and has said qPCR methods are “by far the most sensitive” for detecting pathogenic Aspergillus, while conventional plating methods are “very difficult”. Read about how the USP Calls for Aspergillus Testing on Cannabis. Names qPCR Best Method ‘By Far’

We can also assist with validation and automation to make testing and scalable. Contact us today using the form below!

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