Symptoms of Rabies in Humans
It takes some time (the "incubation period") before a person exposed to rabies develops symptoms. The incubation period for rabies can be anywhere from a week to over a year. An incubation period as long as 19 years has been reported. However, it usually lasts about one to two months. The incubation period varies, depending on the amount of virus introduced into the body and the distance the virus has to travel from the site of exposure to the central nervous system (CNS). The closer the bite is to the CNS, the shorter the incubation period. Bites to the head and neck are usually associated with an incubation period of less than one month.
Rabies generally progresses through four clinical stages: 1) prodrome, 2) acute neurologic period, 3) coma, and 4) death, or in extremely rare cases, recovery.
Symptoms are most often nonspecific and consist of fever, headache, fatigue, loss of appetite, nausea, vomiting, sore throat, and nonproductive cough. The first rabies-specific symptom, pain or paresthesia (abnormal burning sensation) at or around the site of exposure. This occurs in about 50-80% of patients.
The first acute neurologic symptoms may include hyperactivity, confusion, hallucinations, seizures, anxiety, agitation or other bizarre behavior, neck stiffness, or paralysis. Other symptoms and signs seen during the acute neurologic stage are fever, rapid breathing, excessive salivation, twitching, and convulsions. The acute neurologic phase lasts about two to seven days. During this phase the mental status progresses from confusion to disorientation, stupor, and finally coma.
Comas may last anywhere from hours to months. Death during coma usually occurs as a result of respiratory failure or a variety of other complications. Recovery from presumed rabies has only been reported in three cases, all of which had received either pre-exposure prophylaxis or post-exposure