Bat Guano in a Texas Attic: Histoplasmosis Risk and Safe Cleanup
Piles of droppings are often the first sign of bats in a Texas attic. Here is what CDC says about the fungus that can grow in bat droppings, what to avoid doing, how small amounts are cleaned, and why the roost has to be sealed first.
The short version
- Don’t sweep or vacuum dry droppings. CDC says to avoid shoveling or sweeping dry, dusty material because it puts spores in the air.
- Small amounts: wet the material with a light spray, collect it in a secure container, and wear a respirator, gloves, and disposable clothing.
- Large amounts: CDC says large amounts of bird or bat droppings should be cleaned up by professional companies that specialize in hazardous waste removal.
- Stop the source first. The best way to prevent exposure is to prevent droppings from accumulating, which means getting the bats out and sealing the gaps.
What histoplasmosis is
According to CDC, histoplasmosis is a lung infection caused by breathing in spores of the fungus Histoplasma. The fungus lives in soil, and it also spreads in bird and bat droppings that mix in soil. Most people who breathe in the spores do not get sick. When they do, symptoms can include fever, cough, tiredness, chills, headache, chest pain, and body aches, usually appearing 3 to 17 days after exposure.
It can be severe for people with weakened immune systems, and it is often misdiagnosed or diagnosed late because it looks like more common pneumonia. CDC says histoplasmosis does not spread from person to person or between people and pets. If you have pneumonia symptoms after cleaning out droppings, tell your doctor about it.
Where bats come in
CDC says Histoplasma mainly lives in soil in the central and eastern states, such as around the Ohio and Mississippi River Valleys, but it can live in other parts of the country too. It grows especially well in material with large amounts of bird or bat droppings. Unlike birds, bats can become infected with the fungus and may excrete it in their droppings, which is why fresh bat droppings are treated differently from fresh bird droppings on a sidewalk.
CDC also notes that the presence of birds, bats, or droppings is not required for the fungus to grow, and many patients have no such exposure. Its guidance for any material suspected of contamination is to assume it contains Histoplasma and take precautions.
Does it have to be removed?
Not always. CDC’s workplace guidance says that leaving an accumulation alone may be the best course if human activity around it is unlikely. In a Texas attic, the question is whether anyone will go up there, whether the droppings sit on insulation that the HVAC or ductwork touches, and whether the bats are still using the space. Droppings that stay dry and untouched in a sealed, unused area are a different situation from a pile in a space you must enter to service equipment.
What to avoid
- Sweeping or shoveling dry droppings. CDC advises against it.
- Pressure-washing. The Illinois Department of Public Health warns that a high-pressure water stream can make spores airborne before they are soaked.
- Cleaning up while the bats are still there. New droppings keep arriving, and entering a roost during pup season can separate mothers from flightless pups.
- Letting someone with a weakened immune system do the cleanup. Illinois IDPH says to make sure such people don’t clean areas that may harbor histoplasmosis.
- Using formaldehyde or “soil disinfectants.” CDC says no EPA-registered product is approved as a soil disinfectant for Histoplasma and formaldehyde isn’t recommended.
How small amounts are handled
For a small amount, public health agencies describe the same basic steps. Lightly wet the material with a low-velocity spray first. Wear disposable clothing and a properly fitted N95 or better respirator. Collect the wetted material and seal it in heavy-duty plastic bags or another secure container for immediate disposal, keep the respirator on until you are out of the area, then remove and bag the protective gear.
CDC says state and local rules apply to disposal, and some landfills treat contaminated material as infectious waste, so check with your landfill or local authority. CDC also says testing the area afterward is generally unnecessary, but the cleaned area should be inspected visually to make sure no dust or debris is left.
When to call a professional
Large accumulations, droppings that have soaked into insulation, or dust-filled spaces call for a professional with hazardous-waste experience, per CDC. Our cleanup vs. exclusion guide explains how the two jobs fit together: cleanup does not stop bats from coming back, and exclusion alone does not remove what they left.
Order of work in a Texas attic
The order matters. First, inspect and find how the bats are getting in. Then, outside the TPWD May 1 to August 15 period that it discourages exclusion, install one-way devices so the bats can leave but not return, and seal the gaps once they are out. Only after that is the attic empty is cleanup safe and worthwhile. If a bat has come into your living space, read our Texas bats and rabies guide first. For general background, see bats in the attic and Texas bat species.
This guide is general information, not medical advice. If you have symptoms after exposure, see a healthcare provider.
Frequently asked questions
Is bat guano dangerous in a Texas attic?
It can be. CDC says the fungus that causes histoplasmosis grows especially well in material with large amounts of bat or bird droppings, and that bats can excrete it. Most people who breathe in spores do not get sick, but the risk is higher for people with weakened immune systems.
Can I just sweep or vacuum bat droppings?
No. CDC advises against shoveling or sweeping dry, dusty material because it puts spores in the air. Wet the material lightly first, and use a respirator.
How do I clean a small amount of droppings?
Lightly mist the droppings, wear an N95 or better respirator, gloves, and disposable clothing, collect the wet material in sealed heavy-duty bags, then remove and bag the protective gear. Check local rules for disposal.
When should I hire a professional for guano cleanup?
CDC says large amounts of bird or bat droppings should be cleaned up by professional companies that specialize in hazardous waste removal.
Should the bats be removed before the droppings are cleaned?
Yes. New droppings keep accumulating while bats use the roost. TPWD discourages exclusion from May 1 to August 15, so plan exclusion after that, then clean once the attic is empty and sealed.
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