Timeline and Symptoms of a Rabies Infection

Understanding Signs of an Infection and Why It Can Be Fatal

Once the symptoms of rabies begin to appear in a person who has been exposed to the virus, the infection is almost always fatal, with death occurring as few as four days later.

Rabies can be treated, but only if it is treated immediately after exposure. That is why it's critical to seek treatment right away if you think you've been exposed to rabies.

This article explains what symptoms occur during each stage of infection with rabies, how it is diagnosed and treated, and when to see a healthcare provider.

When Is Rabies Fatal?

The rabies virus, a member of the Lyssavirus genus, moves through the network of nerve cells, causing progressive symptoms as it gradually infiltrates the brain and central nervous system.

It's rare for people in the United States to get rabies. Only one to three rabies cases are reported each year. In the decade from 2009 to 2018, the U.S. had 25 cases of human rabies, and seven of those infections were acquired outside of the U.S. and its territories.

Despite being rare in the U.S., rabies remains a frightening prospect: Once symptoms start to appear, death can occur within four to 20 days.

Early rabies symptoms may only include mild fever and headache. As it progresses, severe symptoms like confusion, excessive salivation, seizures, paralysis, delirium, and coma occur. Once this happens, death is almost inevitable.

The following is a timeline of the three stages of rabies: incubation, prodromal, and acute.

rabies symptoms
© Verywell, 2018 

Incubation Period for Rabies

The incubation period is the time between exposure to the virus and the first appearance of symptoms. The period can run anywhere 30 to 90 days on average but may be shorter or longer based on the host and viral factors.

How Many Years Later Can Rabies Take Effect?

Incubation periods longer than one year are exceptionally rare, but it can happen. There have been reports of rabies symptoms beginning years after exposure, including a case of a girl in Ghana who developed symptoms more than five years after a dog bite.

Prodromal Period

The prodromal period is when symptoms first appear. 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:

  • Fever
  • Itching (pruritus)
  • Tingling or burning sensation at the site of the exposure (known as paresthesia)
  • Fatigue
  • Headache
  • Anxiety
  • Irritability
  • Chills
  • Insomnia
  • A general feeling of unwellness (malaise)
  • Loss of appetite (anorexia)
  • A sore, swollen throat (pharyngitis)

Acute Neurologic Period

The acute neurologic period lasts anywhere from two to 10 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 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 cardiorespiratory arrest.

Paralytic rabies accounts for about 20% of cases 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).

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:

  • Agitation
  • Hyperactivity
  • Hyperventilation
  • Excessive salivation
  • Hydrophobia (a distressing symptom characterized by an unquenchable thirst, an inability to swallow, and panic when presented with fluids to drink)
  • Partial paralysis
  • Confusion
  • Vomiting blood
  • Aggression (including thrashing and biting)
  • Hallucinations
  • Seizures
  • Priapism (persistent and painful erection of the penis)

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

Why Are Rabies Patients Afraid of Water?

Hydrophobia results from intense pain and muscle spasms in the throat that make it difficult for a person with rabies to swallow. This may cause avoidance of water, and even the sight or sound of water may trigger spasms.

When to See a Healthcare Provider

If you've been bitten by an animal that is known to or suspected to have rabies, wash the wound thoroughly with soap and warm water and seek medical attention right away. Do not wait for rabies symptoms or signs to appear to seek treatment.

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 the impetus to get the rabies vaccine and reduce your future risk.

What Are the Signs of a Rabid Animal?

You can't tell for certain if an animal has rabies just by looking at it. The only way to know for sure is through laboratory testing. Still, you may be able to spot certain signs and behaviors that would lead you to suspect an animal may have rabies. Here's what to look for:

  • General sickness
  • Problems swallowing
  • Excessive drool or saliva (often depicted as foaming at the mouth)
  • Overly aggressive behavior
  • Biting at imaginary objects (a.k.a. "fly biting")
  • Unexpected tameness
  • Trouble moving, even to the point of paralysis
  • A bat on the ground

The Rabies Vaccine

Even if you’ve been previously vaccinated for rabies, you should still have your wound looked at as soon as possible.

The rabies vaccine can prevent rabies after you've been exposed—but only early on, before symptoms appear. Once you start showing symptoms, the vaccine can no longer prevent you from getting rabies.

Rabies Doctor Discussion Guide

Get our printable guide for your next doctor's appointment to help you ask the right questions.

Doctor Discussion Guide Man

Diagnosing Rabies

Be prepared to provide a healthcare provider with as much information about the animal and the circumstances of the attack as possible.

In the case of a wild, potentially rabid animal that has been caught, a definitive diagnosis requires that the animal be euthanized, after which tissue from different parts of the brain will be removed and analyzed.

It is not necessary to euthanize and test all animals that bite, however. For animals with a low probability of rabies such as dogs, cats, and ferrets, observation periods (10 days) may be sufficient to rule out the risk of potential human rabies exposure.

Several tests are necessary to diagnose rabies in humans, including those performed on samples of saliva, serum, spinal fluid, and skin biopsies of hair follicles at the nape of the neck. Skin biopsy specimens are examined for rabies antigen in the cutaneous nerves at the base of hair follicles.

Your healthcare provider will decide if you need postexposure prophylaxis. The decision will be based on whether you were bitten or exposed otherwise, which animal you were exposed to, and whether the animal is available for testing.

Postexposure prophylaxis may include a dose of human rabies immune globulin and the rabies vaccine on the day of exposure, followed by additional doses of the vaccine on days 3, 7, and 14. People who have been previously vaccinated need only the vaccine.

Summary

While rabies is extremely rare in the United States, it is a lethal disease once symptoms are evident. Symptoms progress through three stages: incubation, prodromal, and acute. Rabies can be diagnosed using brain tissue samples in an animal that is suspected to be infected. Rabies in humans can be diagnosed using samples of saliva, spinal fluid, and skin biopsies.

13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Rod Brouhard, EMT-P
Rod Brouhard is an emergency medical technician paramedic (EMT-P), journalist, educator, and advocate for emergency medical service providers and patients.