Two men in Rochester, New York, have tragically died after contracting a rare fungal infection linked to bat guano—commonly used as a fertiliser in cannabis cultivation. According to Live Science, the men were exposed to harmful fungal spores called Histoplasma capsulatum, which caused a condition known as histoplasmosis.
One of the victims, aged 59, reportedly purchased the guano online to boost his cannabis plants’ growth. The other man, 64, had encountered bat droppings in his attic following a severe bat infestation. While it remains unclear whether the older man had already started using the guano as a fertiliser, both men developed the same deadly infection.
Doctors who treated the cases have issued a stark warning about the dangers of bat guano exposure, especially for home cannabis growers who may be unaware of the health risks.
Why Bat Guano Is Popular Among Growers
Bat guano has long been hailed as a nutrient-rich soil amendment for plants, particularly cannabis. Its appeal lies in its high levels of nitrogen (N), phosphorus (P), and potassium (K), which are crucial for plant health. Depending on its source and processing, bat guano is often marketed with specific N-P-K ratios suited for different growth stages.
For instance:
- Powders with ratios like 8-1-1 or 7-3-1 are ideal for the vegetative stage.
- Phosphorus-rich products like 0-10-0 or 0-12-0 support flowering phases and are often used as compost teas.
These products are widely available online and through gardening suppliers. A quick search for bat guano fertilisers reveals dozens of options, many touting their organic credentials and efficiency.
The Humboldt Seed Organisation blog describes guano as one of the best natural fertilisers due to its varied nutrient content, which depends heavily on where and how it was harvested. But for all its agricultural benefits, the health hazards of bat guano cannot be ignored.
The Hidden Dangers of Bat Guano
Despite its popularity, bat guano carries significant health risks. The National Institutes of Health (NIH) have long cautioned about bats as a reservoir for zoonotic diseases—illnesses that can jump from animals to humans.
Histoplasmosis, the disease at the centre of this tragic story, is caused by breathing in spores of Histoplasma capsulatum, a fungus commonly found in bat droppings. Once airborne, the spores can enter the lungs and trigger serious respiratory infections. Symptoms can range from mild flu-like discomfort to severe, life-threatening complications—particularly in individuals with weakened immune systems.
The Miller Library at the University of Washington highlights that while commercial guano products are often treated to meet USDA Organic Regulations, not all products undergo rigorous processing. Customers are advised to:
- Confirm the origin and treatment standards of the guano with manufacturers.
- Ensure compliance with OMRI (Organic Materials Review Institute) standards.
Are Home Growers at Higher Risk?
Cannabis cultivation, particularly on a personal scale, has seen a boom in recent years. Many home growers opt for organic fertilisers like bat guano, drawn by its natural benefits and easy availability. However, without awareness of proper handling, the risk of exposure to fungal spores increases significantly.
For example, the simple act of opening a bag of untreated guano can release dangerous spores into the air. This is especially hazardous in confined indoor growing spaces with poor ventilation. The same applies to cleaning up bat-infested attics, where droppings may have accumulated over time.
Health experts recommend these precautions:
- Always wear a dust mask or respirator when handling guano or any soil amendments.
- Ensure proper ventilation when working indoors.
- Purchase fertilisers only from trusted manufacturers with clear safety standards.
One small step, like wearing a mask, could mean the difference between safety and serious illness.
A Wake-Up Call for Cannabis Growers
The deaths of the two Rochester men highlight a grim but crucial point: natural does not always mean safe. While bat guano remains a favourite among growers for its nutrient content, its hidden dangers demand careful handling and awareness.
Histoplasmosis is not new, but its association with DIY cannabis cultivation brings the issue into sharper focus. Doctors are urging growers—hobbyists and professionals alike—to prioritise safety and educate themselves on the potential risks of their materials.
As personal cannabis cultivation grows in popularity, so too does the need for better guidelines and safety measures. Whether fertilising plants or cleaning up after bats, handling guano requires more than just gardening gloves. For some, it could be a matter of life and death.
Emily Wilson is a talented wordsmith whose passion for cannabis shines through in her eloquent articles that explore the plant’s cultural significance and historical context. With a focus on arts and lifestyle, she weaves together narratives that celebrate the creativity, innovation, and community fostered by cannabis enthusiasts worldwide. Emily’s unique perspective and engaging storytelling invite readers to embark on a journey of discovery and appreciation for the diverse facets of the cannabis experience.
