The incubation period for rabies is typically 1-3 months. This however could vary from 1 week to a year. Initial symptoms of rabies are usually non-specific and suggest involvement of fever and often pain or unusual or unexplained tingling, pricking or burning sensation (paraesthesia) at the wound site.
As the virus spreads through the central nervous system, progressive, fatal inflammation of the brain and spinal cord develops.
Two forms of the disease can follow:
- Furious rabies during which people infected by the virus exhibit signs of hyperactivity, excited behaviour, hydrophobia and sometimes aerophobia. After a few days, death occurs by cardio-respiratory arrest.
- Paralytic rabies accounts for about 30% of the total number of human cases. This form of rabies runs a less dramatic and usually longer course than the furious form. The muscles gradually become paralyzed, starting at the site of the bite or scratch. A coma slowly develops, and eventually death occurs. The paralytic form of rabies is often misdiagnosed, contributing to the underreporting of the disease.