Rabies

Rabies

Causative Agent

Rabies is a viral disease causing inflammation of the brain (encephalitis). The virus is a member of the family Rhabdoviridae.
Worldwide, several variants of the virus have been identified, each associated with a single wild animal host that acts as a “reservoir of infection” for a particular geographic area.

Distribution

Geographic:

Currently, rabies from insectivorous bats is the only known variant of the virus present in British Columbia.
Bats that have been confirmed with rabies have been found throughout BC; therefore, all bats should be considered as potential sources of rabies. This is particularly true if bats are observed behaving abnormally, such as being found during the day or on the ground.

Seasonality:

The potential for exposure to rabies from bats exists primarily during the spring and summer months when bats are most active.

Click on the photo to enlarge.

Carnivores infected with rabies such as this skunk, often show evidence of having attacked a porcupine.

Hosts, Transmission and Life Cycle

Hosts:

Although all warm-blooded vertebrates are susceptible, only mammals are important in the spread of rabies.
In BC, bats are the only reservoir of rabies. Records of bats submitted for rabies testing suggest that relatively few are infected, even among those submitted because they are behaving abnormally. Bats are a valuable components of the natural ecosystem and many species are at risk in BC. For further information on bats and how to live safely with them, see the BC Ministry of Sustainable Resource Management and Ministry of Water, Land and Air Protection Endangered Species web page.
Other potential hosts in BC include domestic dogs and cats, foxes, raccoons, skunks, wolves and coyotes.
“Spill over” of rabies to terrestrial mammals from bats has occurred in BC, but rabies has never been maintained in wild populations of terrestrial mammals.

Transmission:

Transmission principally occurs through bites of infected carnivores and bats.
Rabies can also be acquired if licked by an infected animal OR if saliva from an infected animal
comes into contact with the mucous membranes of the eyes, nose, lips, or through wounds in the skin.
The rabies virus does not persist in the external environment; the virus is rapidly inactivated through exposure to most detergents, chemicals, ultraviolet radiation, strong acids and bases, and direct sunlight.

Life Cycle:

Rabies viruses move from the site of entry, such as through a wound, and are transported along nerve fibres towards the spinal cord and ultimately the brain, where the virus undergoes replication.
Abnormal behaviour results from the effects of viral infection in nerve tissues.
From the brain, rabies virus is further spread to other organs via the nervous system.
The salivary glands, located in the tissues of the mouth and cheeks, receive high concentrations of virus, making saliva an effective medium for virus transfer when the infected animal bites another animal.

Signs and Symptoms

Rabies should be suspected in any wild animal exhibiting any behaviour considered “abnormal”, including:
- loss of fear or unusual friendliness
- excitation or aggression
- depression
- incoordination
- paralysis
- convulsions or seizures
- abnormal vocalizations
- appearance of nocturnal creatures during the day
- signs of choking or inability to drink or swallow food
- drooling of saliva or frothing at the mouth
- in carnivores, evidence of having attacked porcupines
Bats, unlike many mammals with rabies, may get sick and die before being observed or showing symptoms typically found in other mammals.

Meat Edible?

DO NOT consume meat from an animal with rabies or suspected to have rabies.
DO NOT feed meat from an animal with rabies or suspected to have rabies to dogs.

Human Health Concerns and Risk Reduction

Rabies is a potentially life-threatening disease for humans; signs of infection may not be detectable for weeks or months – left untreated, rabies is always fatal.
Symptoms in humans are similar to those in wildlife:
- depression
- headache
- vertigo
- stiff neck
- inability to drink (“hydrophobia”)
- spasms and paralysis
- left untreated, death results from swelling of the brain or pneumonia
Two human deaths have been attributed to bat rabies in BC. One was a 22-year old college student bitten by a bat while visiting Alberta in 1985, while more recently a 52-year old man died of rabies in January 2003.
Prevention of rabies depends on 4 basic activities:
- Vaccination of domestic animals that live in close proximity to people and which may be exposed to wildlife reservoirs of rabies
- Avoid contact with potentially infected animals. Always consult a health authority if a bat is found in the house. Never approach any wild animal whether it appears to be acting normally or not. Never feed wild animals.
- If there is a high risk of occupational exposure to bats, a rabies vaccination should be considered.
- Any person that is bitten, scratched, etc. by an animal and suspects they have been exposed to rabies should wash wounds immediately with soap and water, disinfected with 50-70% alcohol, and contact the nearest health authority and inform them of the potential exposure to rabies
DO NOT go near any animal suspected of having rabies.
Report any animal suspected of having rabies to the local Ministry of Water, Lands and Air Protection office or the RCMP.
Do not attempt to collect tissues yourself; if possible, submit the entire carcass for testing. Specimens can be frozen.
For small animals such as bats and foxes, double-bag the entire animal in strong garbage bags and place in a leak-proof container.
For larger specimens, contact the nearest Ministry of Water, Lands and Air Protection or Ministry for advice. Contact the nearest Ministry of Water, Lands and Air Protection or Ministry of Health office for instructions on where to submit the specimen.
Further public health information on rabies can be found on this BC Ministry of Health URL.

Samples for Diagnosis

Intact brain tissue is the key diagnostic tool in confirming rabies infection. If an animal suspected of having rabies must be destroyed, it is important that it NOT be killed by gunshot to the head – other forms of euthanasia must be considered.