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The Wisconsin Division of Health (DOH) completed this health consultation in response to a request from a Langlade County resident. This consultation addresses the public health risks associated with living in a home where large quantities of bat guano accumulated in the structure. The health consultation is completed in cooperation with the Agency for Toxic Substances and Disease Registry (ATSDR).


In early March 1998, a resident called to ask about possible health threats from bat wastes. He, his wife, and three young children live in the home. They are bothered by odors and discoloration through walls and concerned about the health threats associated with the presence of bat wastes in the walls and attic. The resident described his home as an old farm house. He said the attic may have been occupied by hundreds of bats for many years. Although he paid an exterminator to remove and seal out the bats, the remaining wastes are a problem. The walls have as much as two feet of wastes packed between studs, and the space above the second floor ceiling has a heavy accumulation. The odors are strong in times of high humidity and temperature. When the exterminator left, he told the resident the bat droppings contain mites.

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