Bird Droppings and Health: What CDC and NIOSH Say

Which diseases are linked to bird and bat droppings?

Three come up most often. Histoplasmosis and cryptococcosis are fungal infections caught by breathing in spores from the environment. Psittacosis is a bacterial infection caught mostly by breathing in dust from dried droppings or respiratory secretions of infected birds. None of them spreads easily from person to person, and CDC's descriptions of all three note that most people who are exposed do not become seriously ill.

Montana Fish, Wildlife & Parks lists histoplasmosis, cryptococcosis and salmonellosis among the diseases associated with pigeons, and histoplasmosis and salmonellosis among those associated with starlings. Those are the two birds behind most heavy accumulations on buildings here, which is why the question comes up on almost every cleanup we look at.

What is histoplasmosis?

CDC describes it as a lung infection caused by breathing in spores of the Histoplasma fungus. The fungus is typically found in soil and in bird or bat droppings, and spores are released into the air when contaminated material is disturbed. CDC says most people who breathe in the spores never get sick. Those who do commonly have fever, cough, fatigue, chills, headache, chest pain and body aches, typically 3 to 17 days after exposure, and the illness is often mistaken for other kinds of pneumonia.

One detail is worth knowing. The Internet Center for Wildlife Damage Management notes that while bird droppings provide suitable conditions for the fungus to grow, the birds themselves do not appear to excrete it, whereas bat droppings often host it. The concern is old, accumulated material and the soil under a long-used roost, not a fresh dropping on a windshield.

Is histoplasmosis a Montana problem?

Less than in much of the country, but not zero. CDC says that in the United States the fungus lives mainly in soil in the central and eastern states, particularly around the Ohio and Mississippi River valleys. Montana is not in that zone. CDC also cautions that the fungus can likely live in other parts of the country and could exist outside the areas shaded on its maps.

Montana has its own entry in the record. A 2013 CDC report described four unrelated histoplasmosis cases diagnosed in Montana residents between late 2012 and early 2013. Three of the four patients had not recently traveled outside the state, and the authors concluded those three likely acquired the infection in Montana, while noting that the source of each could not be determined and that environmental studies would be needed to know whether the fungus is established here. Their advice to clinicians was to consider histoplasmosis in a compatible illness even without travel. The fair summary for a Montana property owner is that the risk is low, not absent, and that sensible precautions cost little.

What about cryptococcosis and psittacosis?

CDC says Cryptococcus neoformans lives in the environment throughout the world, including in soil, decaying wood and bird droppings, and that people are infected by breathing in spores. It says healthy people can get cryptococcosis but that it is not common, that infections are most common in people with weakened immune systems, and that it cannot spread between people or between people and animals.

Psittacosis is caused by bacteria that infect many types of birds. CDC says people most often catch it from pet birds such as parrots and cockatiels or from poultry such as turkeys, chickens and ducks, and that the groups at higher risk are bird owners, pet shop and aviary workers, poultry workers and veterinarians. Symptoms usually begin 5 to 14 days after exposure and resemble other respiratory illnesses, and CDC says antibiotics are the standard treatment. For a building owner dealing with wild birds it is the least likely of the three, but the route is the same: breathing dust from dried droppings.

Who is at higher risk?

CDC names several groups at higher risk of getting histoplasmosis and of more severe infection: people with HIV, organ transplant recipients, people taking corticosteroids or certain immune-suppressing drugs, adults over 55, and infants. It also names people exposed to large amounts of the fungus through work, such as construction workers and farmers, especially those cleaning up after chickens.

NIOSH lists the activities behind work exposures: disturbing droppings, for example scraping them from a structure or cleaning a chicken coop, demolition and renovation, digging, and landscaping. It notes that about one third of histoplasmosis outbreaks in the United States are work-related. If anyone in the household is in a higher-risk group, they should not be the one cleaning out the loft.

Why is dry sweeping the problem?

Because the hazard is airborne dust, not contact. All three infections reach people through the lungs. A push broom, a leaf blower, a dry scraper or a shop vacuum without a high-efficiency filter turns a crust of droppings into a cloud at face height in an enclosed space, which is the exposure the guidance is written to prevent.

NIOSH's instruction is direct: avoid shoveling or sweeping dry, dusty material. The same logic applies to shaking out a nest pulled from a vent, knocking mud nests off a beam dry, or pressure washing a ledge so that the spray carries material into a doorway or an air intake.

What does NIOSH recommend for cleanup?

Start by asking whether removal is needed at all. NIOSH says to consider the amount and location of the material and whether people are nearby, and that leaving it alone may be best where people are unlikely to be around it. Where it must go, NIOSH says to spray the material with water before removal, and suggests adding a wetting agent to help it soak in, then collect the wetted material in a secure container for immediate disposal according to state and local rules. For collection it recommends an industrial vacuum with a high-efficiency filter. It notes that no product is registered as effective against Histoplasma, so disinfectant is not a substitute for careful removal.

On protective equipment, NIOSH calls for NIOSH-approved particulate respirators, properly selected and used. For cleaning large accumulations of droppings it advises considering powered air-purifying or full-facepiece respirators, with filtering facepiece respirators such as an N95 offering less protection. It also recommends disposable protective clothing and shoe coverings, disposable gloves under work gloves, and goggles, with the disposable items sealed in heavy plastic bags afterward. That is how our bird dropping cleanup service is carried out: wet methods, protective equipment and contained disposal.

When is it a job for a professional?

CDC and NIOSH both say that large amounts of bird or bat droppings should be cleaned up by a professional company. Neither gives a homeowner a measurement, so judge by setting: an enclosed space, material built up over more than one season, anything above a ceiling or inside ductwork, or a commercial site where staff and customers pass by. A few droppings on an open deck can be wetted and wiped up with gloves on.

Cleanup without exclusion is temporary. NIOSH's own list of controls starts with keeping birds and bats from roosting in the building, so the cleanup should be followed by closing the access. That is the core of our bird mitigation work, and business owners will find the frontage version in bird droppings at a commercial entrance. Related guides cover birds in attics and soffits and bird mites.

What should you do if you feel sick after a cleanup?

See a healthcare provider and tell them about the exposure: what you cleaned, where, and when. NIOSH's advice to workers is the same, to report symptoms and ask about testing, because these illnesses look like ordinary respiratory infections and the exposure history is what prompts the right test. We cannot tell you whether a cough is related to a cleanup, and no website can.

The rest of this series, including where birds get into buildings in the first place, is in the Montana Bird Control Guide.

Call HJ Property Care & Tree Service at (406) 215-7319 or request a bird assessment and we will identify the species, the access points, and what will actually stop them.

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