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Preventing health problems caused by bats


Bats are flying mammals that are found throughout Québec, both in cities and in rural areas. Active mainly at night, bats feed on insects captured in mid air. Because of the huge number of insects they eat, bats play an important role in the environment.

Bat saliva may, however, contain the rabies virus. Bats can transmit the virus to humans by a bite or a scratch, even a small one. Rabies is an incurable and fatal disease.

Histoplasmosis is another disease that can be transmitted by bats, this time in their droppings. Bat droppings sometimes contain microscopic fungi that cause this disease in humans. There is a risk of getting histoplasmosis in places where large quantities of bat droppings have accumulated.

Histoplasmosis is an infection that generally attacks the lungs. It sometimes affects other parts of the body, for example, the eyes, liver, central nervous system or skin. The symptoms vary from person to person. The disease is rare, usually mild and not contagious. People who get it can be treated.

What to do if you find a bat

If there was contact

If you have had physical contact with a bat, make sure you follow these steps:

  • Wash the skin that was in contact with the bat with soap and water as soon as possible; rub the skin for 10 to 15 minutes.
  • Call Info-Santé 811. A nurse will assess the situation and refer you to a health service if necessary.
  • Follow the instructions the Info-Santé nurse gives you to capture the bat safely if she thinks this is necessary and advises you to do so.
  • Ideally, consult a veterinarian as soon as possible if a pet has had contact with a bat.

If there was no contact

In summer

If you find a bat in your home and no people or pets have had any physical contact with the bat, do not try to capture it. Instead, create a current of air to get it to leave outside, without touching it. Follow these steps:

  • Confine the bat to a room by closing all interior doors to adjacent rooms.
  • Turn off the lights in the room.
  • If there is a door leading to the outside, open it. If not, open the windows, taking care to remove the mosquito screens.
  • Leave the room, closing the door behind you.

The bat will usually find its own way out.

In winter

If you find a bat in your home in winter, capture it by following the instructions for how to capture a bat safely.

The bat will probably be injured, dying or dead. Waking up during hibernation requires a lot of energy, which weakens the bat.

How to capture a bat safely

There are three situations in which you might have to capture a bat that has entered a building:

  • if you had physical contact with it (so that it can be tested to find out if it has rabies);
  • if you are unable to get it to go outside;
  • if the bat is injured, dying or dead, in winter in particular.

When capturing a bat, it is important to take the following precautions:

  • Wear thick work gloves or leather gloves. Cotton or latex gloves are not safe.
  • Confine the bat to a room by closing the doors and windows. Get other people out of the room.

If the bat is injured, dying or dead:

  • Pick the bat up with a shovel or dustpan.
  • If the bat is injured or dying, put it in a container and put the container in a dark, quiet place (e.g., a wardrobe). Contact the Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs at 1-877-346-6763.
  • If the bat is dead, double bag it, that is, put it in a plastic bag lined with a second bag. Throw the bag in the garbage if you did not touch the bat. Otherwise, put it in the freezer.
  • Contact Info-Santé 811 if you touched the bat. The nurse will tell you what to do with the bat that you put in the freezer.
  • Take the gloves off.
  • Wash your hands with soap and water.

If the bat is alive:

  • Wait until the bat lands.
  • Capture the bat by placing a rigid container over it. Slide a piece of cardboard under the container to trap the bat inside.
  • Tape the cardboard to the container so that the bat cannot get out.
  • Release the bat outside if you have not had any physical contact with it. If you touched it, contact Info-Santé 811. The nurse will tell you what to do with the bat.

How to stop bats from getting into a building

Bats are protected species. Killing them is illegal. Instead, you have to try to chase them away when they are found in people’s homes. In summer especially, bats roost in the attics of houses. In winter, they generally leave attics and hibernate in caves or abandoned mines.

Stop bats from getting into a building by taking the following precautions:

  • Make sure the frames and mosquito screens on doors and windows are in good repair.
  • Always close doors leading to the outside and any windows that do not have a mosquito screen.
  • Put mosquito netting over vents that must be kept open, for example, air vents.
  • Inspect the inside of the building to find any holes that provide an opening of at least 2 cm (dime size). Seal these holes to prevent bats in the attic from getting into living spaces.

How to get bats out of a building

Steps to follow

1- Find out where they are getting into the building

To find the openings where bats are getting into the building, look for telltale signs.

  • Inspect the outside of the building. Dark stains and accumulated droppings (droppings are shiny, crumble easily and give off a foul odour) are signs of entry points.
  • Inspect the building at sunset; the places where bats exit at night to go and feed are also entry points.

2- Seal entry points

Once the entry points have been identified, seal them, leaving some exit points open. Do this in the fall. Any type of material will do, since bats will not try to remove what is blocking their entry points. Instead, they will look for another hole that provides an opening of at least 2 cm (dime size) to squeeze into the building and return to their roost

3- Leave some openings so the bats can get out

Once you have sealed off the bats’ entry points, keep one or two access points open. These access points will have to be fitted with a system that will allow the bats to leave their roost yet prevent them from getting back in. To make this one-way system, follow these steps:

  • Get one of the following materials:
    • a piece of polypropylene bird netting;
    • 0.65 cm nylon or steel mesh.

These materials are sold in hardware stores and nurseries.

  • Cut a piece of netting or mesh that is larger than the opening of the entry point.
  • Secure the sides and top part of the netting or mesh over the opening. Leave the bottom part open so that any bats that are still inside can leave the roost by squeezing under the mesh (bats that are outside will not be able to get back in).
  • Permanently seal the last entry points between October and May once all the bats are gone.

It’s best to do this during the day to limit the risk of contact with bats.

Best time to get bats out of a building

The best time to get bats out of a building is between October and May.

In the summer, female bats are very active at night. They leave to go hunting, returning several times to feed their young inside. In the fall, mothers and their young leave their roost for their winter habitat. This means that fall is the best time to get them out. If not, the young will be trapped, with no hope of survival, and the mothers will do everything they can to get inside.

Methods to avoid

No chemical products are approved in Canada to get rid of bats. Furthermore, a bat that has been poisoned with a chemical product may have trouble flying and be more easily approachable. This increases the risk of contact with humans.

Other products or methods only work temporarily and are not recommended. They include:

  • mothballs (naphthalene);
  • smoke or steam;
  • light (attic lighting).

Ultrasound is not effective in getting rid of bats. Glue traps can injure bats and are not recommended.

How to clean an environment contaminated with bat droppings

If bats have taken up residence in your home, you will notice their droppings. To prevent health problems, make sure you clean the contaminated area very well. To find out more about the precautions to take and the steps to follow to clean the area safely, consult the page Cleaning of an environment contaminated with bat droppings.

Last update: June 4, 2018


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