How Bat Guano Turned Deadly For Two Men Growing Marijuana

Two men have reportedly died after inhaling bat guano used to grow marijuana, raising concerns about the safety of natural bat guano and commercially available fertilizers.

The cases of the two men who died from exposure to bat guano used to grow marijuana came to light earlier this month through an accepted manuscript published in the journal Open Forum Infectious Diseases.

The study highlights two fatal cases of histoplasmosis, a fungal infection caused by Histoplasma capsulatum, linked to bat guano exposure among marijuana growers.

Histoplasmosis, most common in the Mississippi and Ohio River valleys, affects 1–2 per 100,000 annually in reportable states, with a 5–7% death rate among hospitalized cases, with many mild cases going undiagnosed, the Centers for Disease Control and Prevention report.

Both cases cited in the study occurred in Rochester, New York, and were linked to either commercially purchased or wild-harvested bat guano used to fertilize marijuana plants. This is noteworthy given the practice of using bat guano as a nutrient-dense “biofertilizer” for marijuana.

How Bat Guano Caused The Deaths Of Two Marijuana Growers

The first case involved a 59-year-old man with a weakened immune system, emphysema, and rheumatoid arthritis who was taking Adalimumab, a medication used to treat rheumatoid arthritis, among other conditions.

He developed respiratory failure, weight loss, and difficulty swallowing. Imaging showed severe lung damage, and a biopsy identified yeast consistent with Histoplasma capsulatum, a fungus commonly found in soil contaminated with bat or bird droppings.

The man had bought bat guano online for use as marijuana fertilizer, unknowingly cultivating the fungus and inhaling it.

Despite treatment with antifungal medications, his condition worsened due to aspiration, and he eventually died.

The second case involved a 64-year-old man with peripheral arterial disease and significant weight loss who had been exposed to bat guano in his attic while planning to use it as fertilizer for marijuana plants.

Imaging showed several lung lesions, as well as cysts in his pancreas and adrenal glands.

He was diagnosed with disseminated histoplasmosis, a fungal infection, and treated with itraconazole.

While the treatment shrank the lesions, complications, including reduced blood flow to his intestines, led to his death.

The Use Of Bat Guano In Marijuana Growing

The study of these two cases highlighted that, with the rise in marijuana cultivation, especially after legalization, growers may be unknowingly exposed to the fungus, and urged the need for testing bat guano in fertilizers and raising awareness about protective measures, like wearing masks.

The researcher of the University of Rochester who conducted this study also said that immunocompromised individuals are at higher risk, and marijuana cultivation should be considered in patient histories to help with early diagnosis and prevention.

Bat guano, which is bat feces, is a natural fertilizer that is particularly high in nitrogen and beneficial for plant growth, including marijuana.

It helps improve soil structure, promotes healthy microbial activity, and aids in better water and nutrient uptake.

Unlike synthetic fertilizers, bat guano releases nutrients slowly, minimizing the chance of overfeeding plants.

Additionally, it helps protect against leaf fungi, encourages growth, enhances resin production, and revitalizes soil.

Marijuana grown with bat guano often has reportedly more complex aromas and flavors than those grown with synthetic fertilizers.

However, the authors of this study emphasized the importance of public awareness, protective measures such as wearing masks, and regulatory testing of biofertilizers to reduce risks, especially for those with weakened immune systems.

The study also urges healthcare providers to be more vigilant when diagnosing histoplasmosis, particularly in marijuana growers and highlights the need for testing commercial bat guano for Histoplasma and educating users on proper handling to avoid fungal infections.