Rabies and Animal Bites Information for Health Professionals

Transmission

Rabies is spread to humans when the virus in the saliva of an infected animal enters through broken skin, the mucous membranes or the respiratory tract. Bites from an infected animal are the main route of exposure. Transmission also occurs through transplantation of organs from infected persons.

Incubation Period

The virus gains access to the central nervous system through peripheral nerves. The usual incubation period is proportional to the distance from the portal of entry to the brain and may vary from several days to years (most commonly 3 to 8 weeks).

Signs and Symptoms

Symptomatic rabies is an almost always fatal viral infection of the central nervous system.  Early symptoms of rabies may include:

• headache
• malaise
• fever
• fatigue
• discomfort or pain at the exposure site (i.e., the site where the person was bitten)

Symptoms progress quickly once the central nervous system is attacked, and the illness generally presents in one of two ways:

1. The more common, agitated (furious) form presents with the classic symptoms of hydrophobia and aerophobia (severe laryngeal or diaphragmatic spasms and a sensation of choking when attempting to drink or when air is blown in the face) with a rapidly progressing encephalitis and death.
2. The paralytic form of the disease manifests in progressive flaccid paralysis, has a more protracted course, and is more difficult to diagnose.

When considering the need for post-exposure management of a patient presenting with an animal bite or scratch, a 5Ws approach may be taken:

Where did the exposure occur?

• There is a higher risk of exposure to animals with rabies in countries or areas at risk.
• Ontario has reduced the number of wildlife rabies cases in the province by more than 99% since rabies control programs began.
  • Ontario was declared to be free of raccoon strain rabies in 2005. However, racoons and skunks in Hamilton, Haldimand-Norfolk and Niagara have tested positive for raccoon rabies in 2015/16.
  • The last rabid fox reported in the province was in 2009.
  • The last rabid terrestrial mammal reported from Toronto was in 1997.
  • Rabid bats are still found in Ontario, including the Greater Toronto Area.

What type of animal was involved?

• Only mammals can be infected with rabies.
• Typically in Canada, wild animals (e.g., raccoons, skunks, foxes, bats) can act as a reservoir of infection for domestic animals (e.g., dogs, cats, ferrets). Small rodents (e.g., rats, mice, squirrels) usually do not carry the rabies virus. Refer to the Canadian Immunization Guide summary table by animal.
• In Asia and Africa, dogs are the main carriers of the disease.

Why did the exposure occur?

• An unprovoked attack is more likely to indicate that the animal is rabid.
• Abnormal behaviour in a domestic pet may indicate that the animal is rabid.
• Generally, it is not possible to assess animal behaviour in wild animals.

Who is the animal’s owner?

• For exposures involving domestic animals, this is important information so public health inspectors can track down the location of the animal for observation purposes.
• If a domestic animal can be observed then rabies PEP is not needed except in unusual circumstances.

Wound evaluation and care

• Bites are the most common mode of transmission of rabies virus. Transmission rarely occurs from non-bite exposures (e.g., scratches), unless there is salivary contact on broken skin or mucous membrane. Petting a rabid animal or handling its blood, urine or feces are not considered exposures.
• Bites on the face, neck or hand are considered higher-risk exposures due to the density of nerve endings in these areas. Bites to the face and neck are also much closer to the central nervous system (CNS), making time to CNS infection much shorter. Therefore consideration should be given to starting rabies PEP for bites to the face and neck when awaiting rabies results on an animal sent for testing.
• More severe or multiple bites provide more opportunity for transmission.
• Immediate and thorough cleaning and flushing of the wound with soap and water for approximately 15 minutes is probably the most effective procedure in the prevention of rabies.
• Avoid suturing the wound if possible.
• Tetanus prophylaxis and antibiotics should be given as appropriate.

If indicated based on the risk assessment, initiate post-exposure prophylaxis as soon as possible, regardless of how long ago the exposure occurred. Post-exposure prophylaxis is very effective in preventing infection in people who may have been exposed to an animal with rabies. 

Post-exposure prophylaxis of persons not previously immunized against rabies

Post-exposure prophylaxis of persons who previously completed a full course of rabies immunization

Vaccine schedule deviations

Vaccination schedules for post-exposure prophylaxis should be adhered to as closely as possible. It is essential that all doses be received. If a dose of vaccine is delayed, it should be given as soon as possible and the schedule resumed. If there has been a significant deviation from the recommended vaccination schedule, immunity can be assessed with serology testing 7 to 14 days after the last vaccine dose.

Contraindications and precautions

There are no contraindications for rabies vaccine or RabIg after significant exposure to a proven rabid animal; however, care should be taken if PEP is to be administered to persons who are hypersensitive to the products or to any ingredient in the formulation or component of the container, including the following potential allergens:

• Imovax® Rabies vaccine: neomycin, phenol red
• RabAvert® vaccine: amphotericin B, chick protein, chlortetracycline, neomycin, polygeline (gelatin)
• Imogam® Rabies immune globulin: latex in vial stopper

Imovax® Rabies vaccine is preferred for vaccinees with a history of hypersensitivity reactions to eggs or egg products. RabAvert® vaccine should only be administered to these persons if Imovax® rabies is not available, and with strict medical monitoring.

Pregnancy and breastfeeding

Pregnancy and breastfeeding are not contraindications to post-exposure rabies prophylaxis.

Common adverse reactions

Common adverse reactions include injection site reactions, such as pain, erythema, swelling, and itching. Serious side effects are rare.

Travellers receiving PEP outside of Canada

• PEP given outside of Canada may include products not approved in Canada. Review available documentation from the patient, including product name, dosage, and route of administration.
• The following vaccines meet WHO’s safety, potency and efficacy requirements:
  • Verorab™ (a purified Vero cell rabies vaccine)
  • Rabipur® (a PCECV vaccine)
• If a WHO-approved vaccine series was started while overseas, the series can be completed with a rabies vaccine approved in Canada. Serological testing is recommended 7 to 14 days after completing the series.
• If the vaccine or schedule are not WHO-approved, consider re-initiating the series using rabies vaccine approved in Canada.
• If the vaccine series was given intradermally and not completed, re-initiate the series using rabies vaccine approved in Canada.
• If no rabies immune globulin has been administered while overseas, it can be provided in Canada up to 7 days after the first dose of any rabies vaccine.

For more information

• Physician Instructions for Administering Rabies Post-Exposure Prophylaxis (PEP)
• Rabies Vaccine and Rabies Immune Globulin Fact Sheet for patients

Pre-exposure Prophylaxis

Pre-exposure prophylaxis is recommended for people at high risk of close contact with rabid animals or the rabies virus, including:

• People with occupational exposure to animals, such as veterinarians and veterinary staff, animal control and wildlife workers
• Laboratory workers handling the rabies virus
• Certain travellers to countries or areas at risk.
• Hunters and trappers in areas with confirmed rabies
• People who explore caves (spelunkers)

Pre-exposure immunization consists of three 1 mL IM doses in the deltoid of rabies vaccine (brand names: Imovax® Rabies, RabAvert®) given on days 0, 7, and any time between days 21 to 28.

Rabies Vaccine and Rabies Immune Globulin Fact Sheet for patients

Protection Measures

The following measures can be taken to protect people and their pets from rabies:

• Pet dogs and cats must be vaccinated against rabies. This is required under Ontario legislation, Health Protection and Promotion Act, Regulation 567
• Make sure that pet dogs are supervised. They should not run loose in public spaces, unless in off-leash parks
• Stay away from all wild animals, especially if they appear tame, injured or sick
• Wild animals that show abnormal or sick behaviour should be reported to 311
• Wildlife-proof the home and yard. Store garbage bins inside a garage/basement until the morning of pick-up.

• Rabies Guidance for Health Care Providers, Public Health Ontario
• Canadian Immunization Guide Chapter on Rabies Vaccine, PHAC
• Guidance Document for the Management of Suspected Rabies Exposure, MOHLTC (PDF)
• Wildlife in The City
• Rabies in Ontario – Ontario Ministry of Natural Resources
• World Health Organization. Rabies Vaccines: WHO Position Paper. Weekly Epidemiological Record 2010; 85: 309-20(PDF)

Physicians have a duty to report animal-to-human exposures that in their opinion may result in rabies under Regulation 557, Section 2(1), of the Health Promotion and Protection Act. Toronto Public Health can assist physicians with risk assessments, manage potentially rabid animals, and provide post-exposure prophylaxis to requesting physicians.

To report an animal exposure to Toronto Public Health:

• During business hours (8:30 a.m. – 4:30 p.m.), call Toronto Health Connection at 416-338-7600 or fax the Animal Exposure Report to 416-696-4297.
• After business hours, fax the Animal Exposure Report to 416-696-4297 or call 311 only if you need to speak to staff after hours.

To order rabies post-exposure treatment, call Toronto Public Health

• During business hours (8:30 a.m. – 4:30 p.m.), call Toronto Health Connection at 416-338-7600.
• After business hours, call 311.

To report human cases of rabies

Physicians have a duty to report suspected or confirmed human cases of rabies immediately to the Medical Officer of Health, under the Health Promotion and Protection Act.

•  How to report a communicable disease