Rabies

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Rabies is a viral zoonotic disease that causes progressive and fatal inflammation of the brain and spinal cord.

Clinically, it has two forms: 

  • Furious rabies – characterized by hyperactivity and hallucinations.
  • Paralytic rabies – characterized by paralysis and coma.

Causes

It is caused by the rabies virus which is transmitted to man through the bite of infected animals: dogs, bats.  Saliva from infected animal contains large numbers of the rabies virus and can be inoculated through a bite, laceration or a break in the skin. Incubation period varies between less than 20 days to 1 year as follows:

Incubation period

Proportion of patients

Conditions

20 – 90 days

75%

 

< 20 days

20%

Bites to face, head and hands; or multiple bites

90 days – 1 year

5%

 

Signs and symptoms

Diagnosis is often difficult: there may be no history of scratch or bite (exposure through licking) or wounds may have healed; a reliable history may be difficult to obtain.

Early symptoms

  • Fever with pain
  • Unusual or unexplained tingling, pricking or burning sensation (paraesthesia) at the wound site

Later stages

  • The virus spreads to the central nervous system, causing fatal inflammation of the brain and spinal cord

Furious rabies

  • Hyperactivity
  • Excitable behaviour
  • Hydrophobia (fear of water)
  • Sometimes aerophobia (fear of drafts or of fresh air).
  • Death occurs after a few days due to cardio-respiratory arrest. 

Paralytic rabies

  • Usually less dramatic
  • Longer course than the furious form
  • Muscles gradually become paralyzed, starting at the site of the bite or scratch
  • A coma slowly develops
  • Eventually death occurs 

Non-pharmacologic treatment

In all cases, even if patient presents late:

  • Cleanse wound or contact site with soap
  • Run water (tap or container) over the contact site continuously for at least 15 minutes to reduce viral load
  • Remove all foreign materials
  • Apply a disinfectant e.g. 10% povidone-iodine
  • For mucous membranes – Rinse thoroughly with 0.9% sodium chloride (normal saline)
  • Do not suture wounds
  • If suturing is indicated, administer rabies immunoglobulin several hours before wound closure.

Pharmacologic treatment

  • No specific antiviral treatment

Prevention

Post-exposure vaccination (PEV)

The decision to start immunization depends on the perceived risk, (nature of contact-broken skin, presence of rabies in the area, status of animal involved). WHO categorizes risks as follows:

Category I

-        Contact with animal or licks on intact skin

No exposure

No PEV

Category II

-        Nibbles on exposed skin

-        Minor bite(s) or scratch(es) without bleeding

Minor exposure

PEV

Category III

-        Transdermal bite(s) or scratch(es)

-        Licks on broken skin

-        Contamination of mucous membranes by animal saliva (licks)

-        Direct contact with bats

Severe exposure

PEV

If the patient has had no prior rabies vaccination, if he or she is of unknown status, or if more than 5 years have passed since his or her last vaccination, active and passive immunizations are provided as follows:

Passive immunization

Human rabies immunoglobulin 20 IU/g instil/ infiltrate intramuscularly around the wound and then, human rabies immunoglobulin 20 IU/kg once daily for seven days

Active immunization

Post-exposure prophylaxis

In those with no previous immunization with rabies vaccine, the vaccine can be administered as deep IM injection as follows

Day 0              1ml in upper arm

Day 3              1ml in upper arm

Day 7              1ml in one upper arm

Day 14            1ml in one upper arm

Day 28            1ml in upper arm

In those previous pre-exposure immunization, post-exposure immunization can be administered as follows:

Day 0              1ml in upper arm

Day 3              1ml in upper arm

 

Pre-exposure Prophylaxis

  • This is given to those at high risk such as laboratory workers, veterinary surgeons and animal handlers

Rabies vaccine

Day 0              1ml

Day7               1ml

Day 28            1ml

Note: Repeat after every 2 years for those at continued risk.

Public Education

The public should be advised to do the following:

  • Teach children at an early age not to handle stray animals or wildlife, especially bats found on the ground
  • Report any animals that are sick or acting strange to local public health authorities
  • Keep pets indoors at night and fenced in or on a leash when outdoors
  • Keep pet food and water dishes indoors
  • Have professional animal trappers remove bat colonies from homes and barns
  • Handle sick or dead animals with heavy gloves and shovels
  • Keep trash container lids tight and maintain compost piles away from dwellings
  • Wash hands with soap and water after contact with wildlife
  • If an animal scratch or bite occurs, especially if due to a dog or bat, immediately wash the areas vigorously with soap and water and immediately seek the care of a physician.

Prevention

  • Vaccinating dogs is the most cost-effective strategy for preventing rabies in people, and human rabies vaccines exist for pre-exposure immunization. 

Referral

  • Refer all patients with symptoms and signs of rabies to a tertiary hospital with an Intensive Care Unit (ICU)