Bugs – Rabies

Rabies is a zoonotic disease (which means that it can be transmitted from animals to humans). It is colloquially known as “Mad Dog Disease”, “Hondsdolheid” in Afrikaans. It is also known as Hydrophobia / “Watervrees”, which relates to one of the major symptoms, an inability to swallow in spite of intractable thirst. 

It is caused by the Rabies virus, belonging to the Lyssavirus genus of the Rhabdoviridae family. 

The virus attacks the central nervous system targeting the brain and the spinal cord.

The incubation period from the time of infection until the onset of clinical symptoms may range from days to many months, depending on where the bite took place (head hand or foot). 

Although stray dogs are the main source of human rabies, responsible for more than 99% of human deaths, any warm blooded mammal, including bats, can carry the virus. 

Rabies is 100% deadly and 100% vaccine preventable.

This disease is endemic in most areas of the world but is very common in the tropics where control of animals is limited. Only a few island countries and Antarctica are free of the disease. 

Eighty percent of human Rabies occurs in Africa and Asia, and children are the most common victims as they may not report scratches or bites. 

The virus is usually transmitted by:​

• a bite​
• a scratch​
• or a lick​

from an infected animal​. 

The virus is most commonly transmitted by (stray) dogs or cats​ but may also be transmitted by wildlife and farm animals e.g. cattle and goats.

• Avoid contact with all unknown animals​.
• Teach children:​
• To  avoid unknown animals​;
• To report ALL animal bites, licks, scratches​.
• Ensure your own animals are vaccinated against rabies.​
• Rabid animals may be “furious” (Majority of cases)​.
• Rabid animals may act “dumb” (Paralytic rabies)​
• Beware: Unusually “tame” wildlife.

At the time of exposure:

• The bite, scratch or lick should be well washed and flushed (minimum 15 minutes) with soap and water to remove as much saliva as possible from the area.
• Apply iodine​
• Do not scrub the wound as this may force the rabies virus into the nerve endings.
• Do not suture​ the wound
• Seek expert medical care
• Dress the wound and obtain post exposure prophylaxis which should be administered in accordance with established treatment protocols dependent on whether the animal was known to be rabid or not, the category of the exposure / wound and the patient’s pre-exposure vaccination status.

In a rabies-endemic area, the circumstances of an animal bite and the animal’s behaviour and appearance may suggest that it is rabid. Domestic animals may be aggressive and attack unprovoked and conversely wild animals may act uncharacteristically tame and timid. All such exposures that involves ANY contact with the animal should be reported to a doctor with a sound knowledge of rabies without delay.

NO attempt to catch or kill the animal should be made for fear of further exposure. Report the animal to the local authorities who should have the animal observed and or euthanized by a qualified veterinarian. Remain in contact with the veterinarian until it can be conclusively confirmed whether the animal did / not have rabies.

Post-exposure treatment to prevent the establishment of rabies infection involves First-Aid Treatment [link to first aid above] of the wound including thorough cleaning.

Definitive Medical Treatment will depend on bite category and pre-exposure vaccination status.

Bite Category

Category I​:
Touching or feeding animals, licks on the skin​

Category II​:
Nibbling uncovered skin, minor scratches or abrasions without bleeding, licks on broken skin​

Category III​:
Single / multiple transdermal bites / scratches, contamination mucous membrane with saliva from licks; exposure to bat bites or scratches

Pre-exposure Vaccination Status

Complete:
Two doses vaccine intra dermal or intramuscular on day zero and day seven.

Incomplete:
No vaccine administered or only one dose received.

Definitive Treatment Guide

Post exposure vaccination must ideally take place within 24-48 hours, but it is never too late to start.

HRIG (if indicated) must be administered within seven days from the date of first post exposure vaccine.

Symptoms

The incubation period ranges from 3 days to 3 years, most commonly between 1 and 3 months. The incubation period is directly related to the extent of the inoculation and the proximity to the brain. Thus, bites on the face and neck are particularly significant and will, in general, be associated with a short incubation period.

In many patients no symptoms occur until the final days of the disease are reached.

The site of the initial inoculation will usually have fully healed and be well forgotten. When the patient begins to experience the first effects of the disease, they may experience fever and headaches and numbness at the original bite site. Following this, patients may complain of anxiety, photophobia, muscular pains and difficulty swallowing.

Like animals, humans may have one of two clinical presentations:

• Furious Rabies: (most common variety – 80%)

The patients experience severe muscular spasms which may lead to temporary loss of breath, if the respiratory muscles are involved. The patients tend to develop spasm of the throat muscles which is precipitated by swallowing, the sound of running water or attempts to drink water, cold drafts across the neck or movement.

• Paralytic Rabies: Less common variety in humans

Death may be delayed but always occurs. Patients tend to lie quietly and because of the gross hypersalivation, saliva dribbles from their mouths. Some patients with furious rabies may have periods of paralytic symptoms.

Irrespective of the clinical presentation the patient remains conscious of his fate throughout the last awful days. 

As rabies vaccine and HRIG in particular is exceptionally difficult to obtain in many countries, all persons living in or travelling to rabies endemic areas should seriously consider pre-exposure vaccine to prevent anxious delays in appropriate treatment.