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Causative Agent

Rabies virus

Incubation Period

20 - 90 days (range 4 days - 19 years)

Infectious Period

Throughout duration of clinical illness


From saliva of infected animals via bites. Rarely, contamination of mucous membranes by infectious material, aerosol transmission and organ transplantation.


Although reservoir is present in many mammalian species, dog bites account for the majority of human infections. Rabies has not been reported locally since 1953. but remains prevalent in many parts of the region and the world. Recent decrease in human rabies cases has been due to improved post-exposure treatment as well as elimination of rabies in animal reservoirs via oral immunisation of wildlife.

  • The first symptoms of rabies usually begin when the virus enters the CNS. A non-specific prodrome of 2-10 days includes fever, malaise, fatigue, anorexia, cough, sore throat, abdominal pain, nausea, vomiting or diarrhoea. The first rabies-specific symptom is pain or paraesthesia referred to the site of the exposure.
  • The acute neurological period manifests as either a hyperactive (furious rabies) in 80% or a paralytic (dumb rabies) form in 20%. Autonomic instability is often prominent (hyperthermia, salivation, hypertension and tachycardia).
  • The neurological phase lasts 2-7 days before development of coma then death.

No tests are available to diagnose human rabies during the incubation period.

After onset of clinical disease, diagnostic methods include:

  • Direct fluorescent antibody staining of skin biopsy from nape of neck (50%).
  • Rabies neutralising antibodies in serum or CSF.
  • Rabies virus isolation from saliva, CSF, urine and tracheal secretions (low).
  • Rabies RT-PCR in saliva, CSF, urine and tissue.
  • Cortical brain biopsy.
    • Specimens may need to be sent overseas for tests.
    • Post-mortem brain examination for Negri bodies and fluorescent staining for rabies antibodies.

Notify all suspected and confirmed cases immediately. Call MOH Communicable Diseases Surveillance team at 98171463 and the Agri-Food and Veterinary Authority of Singapore (AVA) for further investigation.

  • There is no specific treatment for clinical human rabies. Intensive supportive care in the ICU is often used although mortality is virtually 100%.
  • Standard and respiratory precautions should be observed by healthcare workers caring for such patients. Pre-exposure immunisation of medical staff is generally not required. Routine delivery of healthcare is not an indication of post-exposure prophylaxis unless the healthcare worker is reasonably certain that he or she was bitten or mucous membranes or non-intact skin was exposed to potentially infectious saliva or neural tissue.

  • In rabies-free Singapore, the AVA exercises strict control on importation and quarantine of dogs, cats and wild animals and intensive control of stray dog and cat population.
  • In the case of human exposure to animals suspected of having rabies, immediate attempts should be made to identify, capture or kill the animal involved. The veterinarian, AVA, will remove the brain of the animal to examine for presence of rabies virus antigen by immunofluorescence.

Pre-Exposure Vaccination

  • For travellers visiting rabies endemic countries (Central and South America, Africa, Indian subcontinent and Southeast Asia), pre-exposure vaccination may be recommended depending on intended activity, duration of stay, local incidence of rabies and availability of appropriate anti-rabies biologicals.
  • Pre-exposure vaccination greatly simplifies but does not eliminate the need for post-exposure treatment.
  • Pre-exposure vaccination consists of 3 doses given on days 0, 7 and 21 or 28 days.
  • The human diploid cell vaccine (HDCV) is an inactivated virus vaccine available in Singapore.

Post-Exposure Treatment

  • The most effective mechanism of protection against rabies is to wash and flush a wound or point of contact with soap and water, followed by application of ethanol, tincture or aqueous solution of iodine.
  • Suturing should be postponed and where indicated, anti-tetanus toxoid and antimicrobials should be administered.
  • Rabies vaccine and immunoglobulin should be given as soon as possible if indicated (see table below). Post-exposure vaccination consists of 5 doses given on days 0, 3, 7, 14 and 28. Tan Tock Seng Hospital, keeps a stock of rabies vaccine and human rabies immunoglobulin.


Type of contact with a suspect or confirmed rabid domestic or wild a animal, or animal
unavailable for observation

Recommended treatment


Touching or feeding of animals.
Licks on intact skin.

None, if reliable case history is available.


Nibbling of uncovered skin. Minor scratches or abrasion without bleeding.
Licks on broken skin.

Administer vaccine immediately. b
Stop treatment if animal remains healthy throughout an observation period c of 10 days or if animal is euthanised and found to be negative for rabies by
appropriate laboratory techniques.


Single or multiple transdermal bites or scratches.
Contamination of mucous membrane with saliva (i.e. licks).

Administer rabies immunoglobulin and vaccine immediately b. Stop treatment if animal remains healthy throughout an observation period c of 10 days or if the animal is euthanised and found to be negative for rabies by appropriate
laboratory techniques.

  1. Source: Rabies pre- and post-exposure prophylaxis in humans (revised 15 June 2010). Dept of Neglected Tropical Diseases. Neglected Zoonotic Diseases team. WHO, Geneva. Exposure to rodents, rabbits and hares seldom, if ever, requires specific anti-rabies treatment.
  2. If an apparently healthy dog or cat in or from a low-risk area is placed under observation, it may be justified to delay specific treatment.
  3. This observation period applies only to dogs and cats. Except in the case of threatened or endangered species, other domestic and wild animals suspected as rabid should be euthanised and their tissues examined using appropriate laboratory techniques.


  1. Rupprecht CE, Hanlon CA, Hemachudha T. Rabies re-examined. Lancet Infect Dis. 2002; 2:327-43
  2. Whitley RJ, Gnann JW. Viral encephalitis: familiar infections and emerging pathogens. Lancet 2002; 359:507-13
  3. WHO Rabies Fact Sheet No 99 December 2008. Available at Accessed August 2010
  4. Committee on Epidemic Diseases. An imported case of human rabies in Singapore. Epidemiological News Bulletin 1999; 25:71
  5. Warrell MJ, Warrell DA. Rabies and other Lyssavirus diseases. Lancet 2004; 363:959-69
  6. CDC (Atlanta). Human Rabies Prevention. Recommendations of the Advisory Committee on Immunization Practices 2008

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