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Whats wrong with Bat Poop (Guano) ?

Guano Can Make you sick:Middle aged man holding his chest and coughing with his hand in front of his mouth.

I get a few dozen, client inquiries every year, asking if bats can make them sick. Just this month I have had three clients call with concerns finding Bats living in their attics.

I have nothing against Bats and know that they have critical role in removing peak insects from around our homes.  I fact, one bat can eat between 600 to 1,000 mosquitos in just one night.

Bats are social creatures and often live in colonies of hundreds to thousands.

Bats will enter small holes, as small as an inch, in siding, chimneys and screening to access your attic. While they wait for evening to exit, they poop and pee, a lot. Most bats will poop their own body weights worth in just one day. Their waste products are called “Guano”. The guano feeds a host of parasites including cockroaches, mites, fleas. Gross!

A Not So Funny Bat Poop Story:

Mrs. M J, from Sequoia Hills area of Knoxville, called me a few months ago asking if I could perform a inspection to see why her second floor ceiling collapsed. She suspected that it might have something to do with the bats that had been in residence in her attic for the last thirty years. She had known they were there and assumed they were harmless. Needless to say she had never gone into the attic of her 90 + year old house.

The weight of the guano compiled over 30 or more years had overloaded the plaster and lathe ceiling materials and caused the collapse.

The sight of 2 to 3 feet of guano on bedding and furniture, was overwhelming, not mention that it smelled horrible.

Mrs. M J was quite ill, and complained of respiratory ailments, later that night had to be hospitalized for lung problems. The ultimate diagnosis was Histoplasmosis a fungus growing in her lungs.

Our air sampling indicated high levels of mold spores and bacteria counts throughout the home.

Everything was fixable. A professional clean up, to a “white glove” standard, and professional decontamination protocol of the home and contents brought the home back to good health.

Heres a great scientific article on the subject of histoplasma a disease directly related to exposure to bat guano.

Microorganism of the Month: Histoplasma capsulatum

By Agner Martinez, EMLab P&K Analyst

“Histoplasma capsulatum is the etiologic agent of histplasmosis, a common granulomatous disease of worldwide distribution. Inhalation of a sufficient amount of conidia can potentially cause an infection in the lungs of a healthy person. In the vast majority of cases the infection is benign, leaving only residual calcifications in the lung and sometimes the spleen. However, it can occasionally progress to a life threatening, disseminated form, particularly affecting the reticuloendothelial system. There are three varieties recognized, depending on the clinical disease: Histoplasma capsulatum var. capsulatum is the most common cause of histoplasmosis; var. duboisii causes histoplasmosis duboisii, common in Africa; and var. farciminosum causes lymphangitis of horses and mules, and is endemic in Asia, Europe, and Africa.

Despite its worldwide distribution, H. capsulatum is most commonly encountered in tropical or subtropical regions, as well as in several large river basins in temperate regions. The most highly endemic areas in the United States are the central and eastern states, especially along the valleys of the Ohio, Mississippi, and St. Lawrence rivers.

Histoplasma capsulatum is a dimorphic (having two forms) fungus that grows as white to brownish mycelium on natural substrates and in culture at temperatures below 35°C. The organism produces characteristic tuberculate (warty), round, or pyriform (pear-shaped) macroconidia (larger spores; 8-16 µm in diameter) and small (2-5 µm in diameter) round, sparse, or abundant microconidia (smaller spores). When inhaled into the alveolar spaces, it is primarily the microconidia that sprout and then transform into small budding yeasts that are 2 to 5 µm in diameter. In culture at a temperature of 37° C, the organism also grows in the yeast-like form. The variety duboisii differs by the production of larger yeast cells, which are 8 to 15 µm in length with thick walls.  Because of close similarity that exists between spores of Histoplasma and the spores produced by many other fungi, identification of this fungus on spore traps is not possible and could be easily placed under Penicillium/Aspergillus type spores. Similarly, identification of this fungus by direct microscopic examination of tapes, bulks, and swabs is problematic. The most effective method for identifying this fungus is by culturing bulk samples.

The saprophytic fungus Sepedonium also produces tuberculate macroconidia, but is usually distinguishable from H. capsulatum by the absence of microconidia and does not convert to the yeast form at 37°C. Chrysosporium species may also resemble isolates of H. capsulatum. The full identification of the organism requires demonstration of the appropriate exoantigen (inducer of antibody formation, separate or separable from its source) and/or conversion to the yeast form at 37°C. Selective media such as mycobiont agar have been used to grow species of Histoplasma. Once the plates are inoculated they are incubated for 3 to 4 weeks.

It is firmly established that H. capsulatum grows in soil with high nitrogen content, generally associated with the guano of birds and bats. The first isolation of the organism from a natural environment was from soil near a chicken house, and since that time it has been recovered on numerous occasions from bat caves, bird roosts, chicken houses, silos inhabited by pigeons, and other such environments. In avian habitats, the organism seems to grow preferentially where the guano is decaying and mixed with soil rather than in nests or fresh deposits.

Anyone working at a job or present near activities where material contaminated with H. capsulatum becomes airborne can develop histoplasmosis if enough spores are inhaled. After an exposure, how ill a person becomes varies greatly and most likely depends on the number of spores inhaled and a person’s susceptibility to the disease. Infants, young children, and older persons, in particular those with chronic lung disease, are at increased risk for developing symptomatic histoplasmosis. The disease can also appear as an opportunistic infection in persons infected with Human Immunodeficiency Virus (HIV).

Some occupations and hobbies may be at increased risk for exposure to H. capsulatum such as construction, demolition, chimney cleaning, farming, gardening, restoring of historic or abandoned buildings, roofing, bridge inspection, and cave exploration, among others. Individuals likely to come into contact with contaminated soil, bat droppings, bird manures, or similar materials should take appropriate precautions.”

Image of Histoplasma under a microscope with red dye.

We, at Volunteer Mold and Indoor Air Quality highly recommend that you have your home or office inspected if you suspect any rodent or bat activity.

Bob Byrne at Volunteer Inspections is happy to consult with you on your projects and awaits your call. 

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