Symptoms of Rabies

Despite being rare in the United States, rabies remains a frightening prospect due to the speed neurological symptoms can develop and progress. Early infection may be marked only by a mild fever and headache. Symptoms developing after the incubation period (20 to 90 days) will invariably be severe and include confusion, excessive salivation, seizures, paralysis, delirium, and coma. Once symptoms appear, death is, sadly, almost inevitable.

This type of virus, known the lyssavirus, moves through the network of nerve cells, causing progressive symptoms as it gradually infiltrates the brain and central nervous system. That's why, unlike some infectious diseases, you cannot wait for signs of the illness to appear. You must seek treatment the moment you come you are bitten or scratched by an animal that has or is suspected to have rabies.

The symptoms of rabies can be characterized by the stages of infection, broadly described as the incubation period, the prodromal period, and the acute neurologic period.

The incubation period is the time between exposure to the virus and the first appearance of symptoms. The period can run anywhere 20 to 90 days on average but may be shorter or longer based on the severity of the exposure. For example, symptoms in a person with a mild bite may take months to develop. Those with deep or multiple wounds of the neck or head may see symptom progression within weeks. 

Symptoms of rabies during the incubation period may include:

• Fever
• A headache
• Tingling or burning sensation at the site of the exposure (known as paresthesia)

The prodromal period is described by the first appearance of symptoms. This is when the virus first enters the central nervous system and begins to cause damage.

The prodromal phase tends to run from two to 10 days on average and may cause such symptoms as:

• Fatigue
• A general feeling of unwellness (malaise)
• Loss of appetite (anorexia)
• A sore, swollen throat (pharyngitis)
• Nausea
• Vomiting
• Diarrhea
• Agitation
• Insomnia
• Anxiety and depression

The acute neurologic period lasts anywhere from two to seven days and will almost invariably end in death. The types and characteristics of symptoms can vary, depending largely on how severe or mild the initial exposure was.

Furious rabies is the type most people with experience. As its name suggests, this form of rabies is characterized by violent physical and neurologic symptoms. Symptoms may come and go, and will often be interspersed with moments of calm and lucidity. Death will most often be caused by cardio-respiratory arrest.

Paralytic rabies affects up to 30 percent of people and will cause muscles to gradually weaken, starting from the site of the exposure and expanding outward. Paralysis and death will eventually ensue (usually by respiratory failure). Most paralytic cases are believed to be caused by a minor injury, such as a nip, that has gone unnoticed.

Atypical rabies is a type most often associated with bat bites. It may involve symptoms from both furious and paralytic forms of the disease. The variations in symptoms and severity can often make it hard to recognize a case as rabies.

Symptoms of rabies occurring during the acute neurologic period may include:

• Hyperactivity
• Excessive salivation
• Hydrophobia (a distressing symptom characterized by an unquenchable thirst, an inability to swallow, and panic when presented with fluids to drink)
• Priapism (persistent and painful erection of the penis)
• Extreme sensitivity to light (photophobia)
• Paranoia
• Confusion and incoherence
• Aggression (including thrashing and biting)
• Hallucinations
• Seizures
• Partial paralysis
• Delirium

These symptoms will soon to lead to a coma as the rabies infection causes massive brain inflammation. Without intensive supportive care, death will usually occur within hours or days.

Once rabies symptoms begin to appear, the infection is almost always fatal. To this end, you need to seek care the moment you are bitten by a wild animal—or even a domestic one.

Start by washing the wound thoroughly with soap and warm water. While a doctor should be seen as a matter of urgency, the condition is not considered to be a medical emergency at this stage. It is simply important to see a physician, ideally on the same day, and to provide as much information as you can about the attack. Even if you've been previously vaccinated for rabies, you should still have your wound looked at since the vaccine only provides around 10 years of protection.

If the animal has been captured (or the suspected pet quarantined), tests can be performed to determine whether it has rabies. But, even then, treatment wouldn't necessarily be delayed pending the results. This is because the only sure way to confirm rabies is to euthanize the animal and obtain two tissue samples from the brain. Clearly, with a domestic animal, this may be less of an option if the symptoms are vague, non-specific, or nonexistent.

Whatever the circumstance, if there is a genuine suspicion of exposure, treatment should be started without delay.

On the other hand, if you have been scratched by a suspicious animal or have come into contact with body fluids from a sick or dead animal, you should still see a doctor if only for your peace of mind. This is especially true if you live in an area where animal rabies has been identified.

While rabies can only be transmitted through saliva or brain/nerve tissues, any potential exposure, however small, should be taken seriously. If anything, it may provide you the impetus to get the rabies vaccine and reduce your future risk.