Growers Network Staff

December 15, 2017 5 min read
December 15, 2017
5 min read

Aspergillus: The Most Dangerous Cannabis Pathogen

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In this article from Medicinal Genomics, Ben Amirault discusses one of the most dangerous pathogens that can be found on commercially-available agricultural products.

The following is an article produced by a contributing author. Growers Network does not endorse nor evaluate the claims of our contributors, nor do they influence our editorial process. We thank our contributors for their time and effort so we can continue our exclusive Growers Spotlight service.


This Contributors article has been reproduced with permission from Medicinal Genomics. The original article can be found here.

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 29 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?

A vial containing Aspergillus.

Aspergillus is a saprophytic fungus (detritivore) 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?

While there is little risk of developing aspergillosis in otherwise healthy individuals, those with compromised immune systems, either through disease or medical treatment, are at serious risk of developing the 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:

  1. the ingestion of immunosuppressive drugs (after undergoing bone or organ transplants)
  2. a low white blood cell count (resulting from chemotherapy)
  3. asthma or cystic fibrosis
  4. 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.

Editor’s Note: Just to highlight, a survival rate of 59% is incredibly low, and 25% is insanely low.

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.

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 ingestible form typically is not a concern because the stomach is not a suitable environment for Aspergillus to live and thrive.

Related Articles: Smoking vs. Eating Cannabis: The Effects on Patient Health

Who tests for Aspergillus?

Currently, Alaska requires testing cannabis for aspergillus flavus, aspergillus fumigatus, and aspergillus niger. California published proposed testing requirements earlier this year that included Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, and Aspergillus terreus. We have heard that other states are looking into implementing similar requirements.

Medicinal Genomics can help labs test for Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, and Aspergillus terreus using our Our PathogINDICAtor® qPCR Microbial Detection Platform. Our Aspergillus Multiplex Assay can test for all four pathogens in a single reaction. Data from our peer-reviewed study shows that qPCR-based testing for aspergillus is far more accurate than culture-based methods. In fact, we believe Aspergillus species cannot be accurately quantitated with culture-based methods and should not be used for cannabis safety testing. More on that here.

We can also assist with validation and automation to make testing and scalable. Contact us today for more information.

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Want to get in touch with Medicinal Genomics? They can be reached via the following methods:

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About the Author

Ben is the Marketing Manager at Medicinal Genomics (MGC) and enjoys the challenge of trying to simplify the amazing science performed in the MGC lab into content for the layman. Ben also maintains and helps to organize and execute MGCs annual CannMed Conference. Prior to joining MGC Ben worked as an writer and editor. He earned his journalism degree from the University of New Hmapshire.