Rabies is a zoonotic, infectious disease that mainly transmits to humans through dog bites. However, wild animals like foxes, bats, raccoons and skunks can also can transmit the rabies virus to human’s trough bits or scratches in the skin. Left untraded the infection is virtually 100% fatal.
After entering the body, the rabies virus infects the nervous central system. The virus then migrates though the nervous central system to the spinal cord and later the brain where it causes inflammation (encephalitis) and death.
Period of incubation varies. Normally it takes 1 – 3 months from being exposed to rabies to symptoms arises. However, it may vary from 1 week to 1 year, dependent on where the person is bit and the amount of virus entering the body.
Symptoms
In humans
Humans can experience fewer with pain, picking, tingling or burning sensation around the wound site. If the virus spreads to the central nervous system, the virus will cause a progressive impanation in the spinal cord and brain.
WHO describes to forms of the disease, furious rabies and paralytic rabies.
Furious rabies: signs of hyperactivity, hydrophobia (fear of water), anxiety and nervous behaviour (excitable behaviour). Sometimes the individual can experience aerophobia (fear of fresh air or drafts). Death occurs a few days after symptom debut due to cardio and respiratory arrest.
Paralytic rabies: In 20 % of the human cases, the disease has different symptoms and usually longer course. Starting at the site of wound or scratch, muscle paralysis gradually occurs. Coma gradually develops, before death occurs. The paralytic form of rabies is often misdiagnosed, and thus underreported.
In animals
Symptoms of rabies in dogs can be fewer, abnormal behaviours (like aggression), hyperactivity, and changed pattern of movement and paralysis in some part of the animal’s body. After 1 -2 weeks after symptom’s debut the animal dies.
Prevention
It is possible to prevent and control the spread of rabies. According to WHO, this can be achieved by vaccination of dogs, spread of knowledge of dog behaviour and bite prevention and immunization of people after exposure to rabies, called post-exposure prophylaxis or PEP.
WHO also recommend pre-exposure immunized (vaccinated) against rabies for expatriates living in remote high exposure risk areas with limited access to rabies biologics. They also recommend outdoor travellers, children living in or visiting these areas to get immunized.
Post exposure prophylaxis (PEP)
After exposure to rabies it is important to imminently start post-exposure prophylaxis (PEP). PEP prevents the entry of the virus into the central nervous system, saving the life of the exposed person.
The WHO describes PEP in three steps:
- right after suspected exposure to rabies, the wound or scratch is excessively washed and locally treated.
- immunization of the exposed person by an effective rabies vaccine that meets the WHO standard.
- administration of rabies immunoglobulin (RIG), if indicated.
Step 1. Includes:
Extensive wound washing includes immediate, thorough washing and flushing of the wound. This is performed for a minimum of 15 minutes with soap and water, detergent, povidone iodie or other substances that can kill or remove the rabies virus.
For more information about PEP, please read the WHO fact-sheet about rabies.
The rabies virus
The rabies virus is a part of a family of viruses called Rhabdoviridae, and belongs to the genus lyssavirus. It is a single stranded RNA virus that codes for 5 proteins called N, P, M, G and L. The structure of the rabies virus is determined by sequence of the five proteins.
More information about the rabies virus can be found at the CDC.
