White-nose syndrome (WNS) is an infection caused by the microscopic fungus Pseudogymnoascus destructans. It is the main cause of the decline of bat populations living in caves in North America, including those in Québec.

Wildlife at risk

All species of North American bats can be affected by white-nose syndrome. In Québec, the disease particularly affects the following species:

  • Little brown bat;
  • Northern long-eared bat;
  • Big brown bat;
  • Eastern pipistrelle.

Signs of the disease in wild animals

Bats infected with the white-nose syndrome have white spots on the nose, ears or wing membrane in winter. In affected individuals, it is not uncommon to see a lack of or low fat reserves. These reserves allow them to survive during hibernation. Early awakening in the spring and flying behaviour in broad daylight are common in affected bats. In the early years of detection of the disease in a population, a mortality rate of more than 90% can be observed.

Transmission and incubation period

The fungus that causes white-nose syndrome generally develops in cold, moist environments such as caves and mines. It can affect bats during hibernation by growing in animal tissues, even if they are alive. Bats must lower their body temperature to hibernate. They become a suitable host for the growth of fungi.

The fungus is transmitted by direct contact between bats when they congregate during breeding and hibernating periods.

Once present in one location, the fungus persists in the environment for a long time and can easily be spread by bats from a contaminated site to an area that is not.

Humans can also spread the fungus with their boots, clothing or equipment used when visiting caves. In fact, humans are probably responsible for the introduction of the fungus in North America after visiting a contaminated European site. 


There is no effective large-scale treatment for this infection. Several experimental treatments are being tested (e.g., vaccine, probiotic, antifungal).

Protection and prevention

It is recommended to clean your boots, clothing and hands when visiting a cave to avoid spreading the fungus. It can be present in a location without the bats necessarily showing signs of the disease. Appropriate decontamination measures must be applied before and after each visit to a cave. Refer to the decontamination procedures This hyperlink will open in a new window.. You can also view the national decontamination protocol video This hyperlink will open in a new window..

If you are visiting several caves, be sure to visit those where white-nose syndrome cases have not been confirmed before sites that are contaminated. Refer to maps to locate areas where the infection has been confirmed This hyperlink will open in a new window..

Risk for wildlife health

White-nose syndrome only affects bats.

Risk for human health

White-nose syndrome is not considered a threat to human health. However, it is important to remember that bats should never be touched. A small number may be infected with rabies, a fatal disease for humans.

 If in contact with a bat, wash exposed skin with soap and water for 10-15 minutes. Contact Info-Santé 811 promptly. Follow our prevention tips. Check out these tips if a bat is in your home This hyperlink will open in a new window..


The government is conducting a number of surveys to better understand the status of Québec’s bat populations and to assess the impacts of white-nose syndrome.

Among these, the government participates in the monitoring network of summer bat colonies, Neighbourhood Bat Watch. This network relies on citizens reporting places used by bats during the summer, such as a cottage, a house or a shed. You can report bat sightings on its website This hyperlink will open in a new window..

Last update: January 8, 2024


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