Bats & Public Health

Contrary to popular belief, few parasites and diseases of insectivorous bats (those bats that eat only insects) pose any threat to human health.

  • When bats inhabit a building, they pose little threat to the safety of people or other animals.
  • Their nocturnal habit of feeding on insects means they seldom interact with humans.
  • There are few valid accounts of bats attacking people. Even rabid bats rarely become aggressive.

Some diseases of potential concern are discussed below:

Bat Diseases

Histoplasmosis

Histoplasmosis is a very rare respiratory disease in humans caused by a fungus that grows well in soils enriched with animal droppings.

In North America human cases are known primarily from the humid areas in the Mississippi and St Lawrence river valleys in association with accumulated guano of pigeons, starlings, and bats. However, the fungus requires ongoing warm, moist conditions and is rarely found in Alberta. There is only one report of the fungus in the province.

In 2003 a cluster of four human cases was documented in the Edmonton area. All individuals worked together on a golf course and were involved in a project to replace some sod. The sod originally came from British Columbia. Apparently there were fungus spores either in the sod or in the ground where the new sod was lain.

Rabies

Rabies is an acute infectious disease of the central nervous system. It has been identified in a few bat species throughout Canada and the United States.

It should be noted, however, that much information about rabies has been sensationalized and misrepresented. While individual bats should be handled cautiously, widespread fear and persecution of bats is unwarranted.

A summary of what is known about rabies in insectivorous bats can be found at:

Rabies Risk and Prevention

The risks and preventive measures to safe-guard against rabies in Alberta are outlined below:

Alberta Bat-Related Rabies Infection Cases

There have been very few recorded human fatalities due to exposure to rabies in Alberta:

  • In July 1985, a man apparently contracted rabies from a big brown bat in northern Alberta. He did not notify health officials at the time and did not receive rabies preventative vaccine before or after the exposure. In December 1985, the man died of the disease.
  • In 2007, a case of bat-related rabies occurred in central Alberta. Similar to the first case, the initial encounter with a bat was not reported to health officials.

Bat Handling and Rabies Infection

Although rabies virus infection rates in bats are extremely low throughout North America, care should always be taken when handling a live bat.

Like most wild animals, biting is a natural defensive reaction for bats whenever they are confined. While most bats do not pose a concern, some basic precautions should be applied:

  • Any bat found on the ground should be collected and tested for rabies (contact the District Federal Veterinarian or any Fish and Wildlife office).
  • If the bat is handled, gloves should be worn.
  • You can avoid handling the bat by using a stick or other object to gently push the grounded bat into a pail or a box.
  • If a person is bitten, the wound should be washed immediately and medical assistance should be sought. The animal should be collected if possible and submitted for rabies testing.

Preventing Bat-Related Rabies Infection

Although the prevalence of rabies is low in bats in Alberta, any incident resulting in direct contact and a bite from an unknown bat should be reported immediately to health officials. Appropriate follow-up procedures can then be considered.

Wearing gloves when handling any live bat is the best way to prevent possible rabies infection.

Anti-Rabies Vaccine

A fast, effective, and relatively painless anti-rabies vaccine is available to prevent the disease in humans. The injections are very similar to getting a flu shot.

Pre-exposure immunization should be considered in any occupation with a high potential for contacting wild animals.

Gone are the days when contact with a rabid animal leads to a long series of painful inoculations, often with unpleasant side-effects. The current vaccine, human diploid cell vaccine, requires a maximum of five inoculations administered into the muscles of the upper arm to give full protection against infection.

Because the vaccine is of human origin, there is little or no reaction against it. And the protection provided develops rapidly and lasts a long time.

Bat Parasites

Ectoparasites (Bat bugs)

Ectoparasites, primarily bat bugs (Cimicidae), that live on bats only try to bite people if there are no bats to feed on (i.e., AFTER control measures to eliminate bats have been taken).

Bat bugs rarely feed on humans in Alberta and, while an annoyance, they are not considered dangerous since they are not known to transmit any diseases.

 

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Updated: Jan 9, 2014