Symptoms of Rabies

Why Treatment Is Needed Before Symptoms Appear

snarling dog
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Despite being rare in the United States, rabies remains as frightening as ever due to the speed by 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 almost inevitable.

Unlike some infectious diseases, you cannot wait for signs of the illness to appear. Rather, you need to seek treatment the moment you are bitten or scratched by any animal suspected of having rabies.

Stages of Infection

Rabies is caused by a type of virus, known the lyssavirus, which is primarily transmitted to humans by animal bites. The virus can found in high concentrations in the saliva and brain/nerve tissues and less so in blood, urine, or feces where it is not considered infectious.

Once you have been bitten, the virus will move through the network of nerve cells, causing progressive symptoms as it gradually infiltrates the brain and central nervous system.

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.

Incubation Period

The incubation period 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. A person with a mild bite, for example, may take months before symptoms develop. Those with deep or multiple wounds of the neck or head may progress within weeks. 

Symptoms of rabies during the incubation period may include fever, headache, and a tingling or burning sensation at the site of the exposure (known as paresthesia).

Prodromal Period

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

Acute Neurologic Period

The acute neurologic period lasts anywhere from two to seven days and will almost invariably end in death. Tthe 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 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.

When to See a Doctor

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 at this stage to be a medical emergency. It is simply important to see a doctor, ideally on the same day, and to provide as much information as you can about the attack.

The doctor will be able to advise you whether treatment is needed. Even if you've been previously vaccinated for rabies, you should still have it 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, treatment should be started no later than 10 days after exposure.

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.

Sources:

Centers for Disease Control and Prevention (CDC). "Human Rabies." Atlanta, Georgia; updated August 23, 2017.

CDC. "Rabies: When should I seek medical attention?" Issued April 22, 2011.

Yousaf, M.; Qasim, M.; Zia, S. et al. "Rabies molecular virology, diagnosis, prevention, and treatment." Virol J. 2012; 9: 50. DOI 10.1186/1743-422X-9-50.