Bird and bat droppings may seem like a nuisance, but large accumulations in attics, barns, steeples, warehouses and other structures can pose health risks. The best-known is histoplasmosis, a fungal infection associated with soil and droppings in certain regions, including parts of the Ohio and Mississippi River valleys. This guide explains the risks and how cleanup is done safely.
Histoplasmosis
Histoplasmosis is an infection caused by the fungus Histoplasma. According to CDC and NIOSH, the fungus lives in the environment, particularly in soil that contains large amounts of bird or bat droppings, and people get histoplasmosis by breathing in microscopic fungal spores from the air. In the United States, Histoplasma is found mainly in central and eastern states, particularly around the Ohio and Mississippi River valleys.
CDC notes that fresh bird droppings on surfaces such as sidewalks and windowsills likely do not pose a risk for histoplasmosis. The concern is disturbing large, older accumulations, which can release spores into the air.
Other organisms
Accumulations of bird and bat droppings can also harbor other organisms, such as Cryptococcus in pigeon droppings, and birds can carry bacteria such as Chlamydia psittaci. Bats can carry rabies, so never handle bats with bare hands.
Activities that raise risk
NIOSH identifies disturbing large accumulations of bird or bat droppings, such as scraping droppings from a bridge, shoveling droppings from a building or cleaning a chicken coop, as activities associated with exposure. Demolition, construction and renovation in affected areas can also raise risk.
Exclusion comes first
NIOSH notes that the best way to prevent exposure is to prevent droppings from accumulating in the first place, by excluding birds and bats from buildings. Before cleanup:
- Birds: a wildlife or pest professional can install netting, deterrents and close openings.
- Bats: exclusion must allow bats to leave and keep them from returning, and many states protect bats and restrict exclusion during certain seasons. Never seal bats inside.
Safe cleanup practices
NIOSH guidance for workers emphasizes reducing dust and using protective equipment:
- Plan the job and keep unprotected people away.
- Suppress dust by spraying water or using other dust suppression methods before and during removal.
- Wear protective equipment: NIOSH materials show coveralls with hoods, NIOSH-approved respirators and eye protection.
- Remove droppings carefully and bag them.
- Remove contaminated materials such as insulation that can't be cleaned.
- Clean and disinfect surfaces after removal.
- Decontaminate before leaving the work area, and launder or dispose of clothing appropriately.
When to call professionals
- Large or old accumulations
- Attics, wall cavities, steeples and enclosed spaces
- Bat colonies
- Commercial and industrial buildings
- People with weakened immune systems in the household
- Any job requiring respirators
Health symptoms
Many people exposed to Histoplasma have no symptoms or mild symptoms. Some develop flu-like illness, and people with weakened immune systems can develop serious disease. NIOSH advises workers with exposure or symptoms to seek medical evaluation and tell their healthcare provider about their work. Anyone with concerns should see a provider.
Structural damage
Large accumulations can also damage roofing, wood and insulation, cause odors and attract insects.
A practical example
A church discovers a large accumulation of pigeon droppings in its bell tower. A wildlife professional installs netting and closes openings. A cleanup crew in coveralls and respirators mists the droppings with water, removes them in sealed bags, removes contaminated insulation, cleans and disinfects surfaces, and seals the waste for disposal. Parishioners stay out of the tower during the work.
Employers and workers
NIOSH advises employers whose workers may disturb accumulations, such as roofers, HVAC technicians, construction and demolition crews, and maintenance staff, to develop a site safety plan, provide protective equipment and training, and encourage workers with exposure or symptoms to seek medical evaluation. Employers using respirators must follow OSHA's respiratory protection standard, including medical evaluation and fit testing.
Disposal
Bagged droppings and contaminated materials are usually disposed of as ordinary solid waste, sealed to prevent dust release, though local rules may vary. Ask your contractor how waste will be handled.
Frequently asked questions
Is a little bird poop on my deck dangerous?
Fresh droppings on outdoor surfaces likely pose little histoplasmosis risk for healthy people. Clean with gloves and wash hands.
Can I clean my attic myself?
Small amounts may be manageable with dust suppression and protection, but large accumulations and bat colonies are best left to professionals.
Do disinfectants kill Histoplasma?
Disinfection is part of cleanup, but removing droppings with dust control and protecting workers' breathing are the key steps.
Are bats protected?
Many states protect bats; follow state rules for exclusion timing.
Does insurance cover cleanup?
Many policies exclude damage from birds, bats and rodents. Check your policy.
Is histoplasmosis contagious?
It isn't spread from person to person.
Key takeaways
Large, old accumulations of bird and bat droppings can harbor Histoplasma and other organisms. Exclude birds and bats first, suppress dust, wear coveralls, respirators and eye protection, remove droppings and contaminated materials carefully, and disinfect. Use professionals for large jobs, enclosed spaces and bat colonies.
Sources
- CDC/NIOSH: Histoplasmosis and Work
- NIOSH: What Workers Should Know about Histoplasmosis (Pub. 2022-104)
- OSHA: 29 CFR 1910.134, Respiratory Protection
This guide is general information. It is not legal, medical, environmental or safety advice. Rules vary by state and locality. For a specific situation, consult the relevant agency or a qualified professional.