The Hidden Danger of Bat Guano
Ask nearly anyone, and you’ll hear that bats (although beneficial in insect control) can be dangerous because they carry rabies. But a lesser known danger, and one that is not as easy to avoid, is histoplasmosis, a disease you can get from exposure to bat guano (bat droppings).
What is Histoplasmosis?
It is an infectious disease caught by inhaling the spores of the histoplasmosis capsulation fungus. While it is not contagious, the disease can affect a wide variety of the population who may not even be aware they are at risk.
Should I be concerned about getting histoplasmosis?
Anyone can get histoplasmosis. There are, however, certain people whose occupations make the risk of exposure greater than others. Included in that group are chimney cleaners, construction workers, gardeners, HVAC installers or repair people, roofers, and, of course spelunkers (cave explorers). In reality, however, anyone who comes across the fungus can get histoplasmosis.
But I’ve never touched or been bitten by a bat. So how could I get it?
It’s easier than you might think. Bats become infected with histoplasmosis, and their feces contain the histoplasmosis fungus. This fungus grows in the soil where the droppings land, or in the droppings found in an attic occupied by bats. The fungus then continues to grow, just waiting for you or me to come along to clean out the old barn, the attic, or other place where the spores now lie.
Or sometimes, we disturb the dirt (cleaning up the garden, sweeping out the empty building, or doing other seemingly harmless dirty work), causing the spores to become airborne. When we breathe that air, we then become infected with the histoplasmosis fungus and the real trouble begins.
I don’t do that kind of work. I shouldn’t have to worry about that, right?
Not really. In fact, in 1970, several hundred middle school students developed histoplasmosis, simply because they breathed the spores through their school ventilation system over the few days following a “clean up” of the school’s courtyard as an Earth Day project. Even those children who were not present at the clean up were exposed to the spores over the next few days and came down with histoplasmosis. It was later determined that the spores were spread through the school’s ventilation system.
And there are cases where people have been exposed when working in a city near construction sites where soil containing the histoplasmosis spores was disturbed when the site was excavated. The spores became airborne, and the office workers then breathed the spores through their office ventilation system. Anyone can get histoplasmosis.
How do I know if I have it?
The disease first affects the lungs, and often those with the disease have no or very mild symptoms within the first few days. On an average, around 10 days after exposure, many sufferers complain of flu-like symptoms: fever, chest pain, loss of appetite, dry cough, headache, shortness of breath, impaired vision, and possibly joint and muscle pains. Because of the vague symptoms, you may have been exposed to the disease and not know it.
In many cases, the disease may run its course, and you will think you’ve simply had a case of the flu. Some cases, however, are more serious, leading to long-term illness, often resembling tuberculosis in nature. And some cases, if not treated, are fatal.
If you have a weakened immune system (are undergoing chemotherapy, have AIDS, etc.) or are a heavy smoker, you may be more susceptible to getting histoplasmosis. And if you’ve had it in the past, you are subject to a re-infection or reactivation of the disease after another exposure. This is especially true for the elderly, those with compromised immune systems, and the very young.
If it’s so hard to recognize, how is it diagnosed?
If you suspect you may have been exposed, you should immediately contact your health professional, telling them you may have been exposed, and ask if they recommend tissue or blood tests. The more accurate tests (tissue samples) take a long time for results to show; the quicker tests often show false positives. Thus, it is imperative that you quickly seek medical attention if you think you have been exposed.
If I have it, then what?
Although mild cases may disappear on their own, you should contact your health professional to make sure you are not one of those who should be taking antifungal medicines. Sometimes the disease is spread throughout the blood system (called disseminated histoplasmosis), and if that is the case, medicine is necessary.
How can I keep from getting it?
When you are cleaning an old attic or building, avoid areas that may harbor the fungus, especially if there are accumulations of bird or bat droppings.
Spray a mist of water over contaminated sites if you have to work there. This will help to keep down the dust (and thus the spores).
If you must work around a contaminated area, wear disposable clothing and specially designed face masks that can filter particulate matter of 1 milli-micron in diameter.
Keep bats and birds from nesting in areas in buildings such as barns, and in your house attic or eaves.
Note that you may have to have your home or building cleared of bats and/or bird roosts. If that is the case, it is best to have a company specializing in bat control do this. They will know the proper ways to control the spores and have appropriate clothing and equipment to minimize the risk of getting or spreading the disease.
I have scattered droppings in my attic. Is it safe to vacuum them up?
Scattered bat droppings (guano) do not pose a risk and can be safely swept up or vacuumed. Of course – the dust often found in attics may be an irritant, and you might be wise to wear a dust mask – there is very little risk of Histoplasmosis. It is when the guano starts to accumulate and pile up that the fungus can grow and develop spores.
When bat control professionals clean up these droppings, they use industrial vacuums with special high-efficiency filters, thus reducing the risk to the worker. Even then, the experts don protective clothing and air masks to avoid breathing the spores.
I have a pile of bat droppings in the corner of my attic that is 8 inches deep. Is it okay to be in the house?
Generally, there is no problem if the droppings are not disturbed or if the air vents do not pull up air from that area. However, you should have an expert determine your risk factors in this case.
I had bats living in my wall. Now I have a smell. Is it safe to breathe the air?
While breathing the air may not be pleasant, you should not have problems associated with histoplasmosis. However, be aware that bats may carry bat mites, fleas, and other insects, and they are likely to find a way into your living area. Also, if a bat is trapped, it may die, and the smell of the decomposing bat, as well as the guano, may be very unpleasant. It is best to have the bats removed as quickly as possible.
By Michael Koski