Rabies

Rabies is a topic covered in the 5-Minute Clinical Consult.

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Basics

Description

  • A rapidly progressive central nervous system (CNS) infection caused by a ribonucleic acid (RNA) rhabdovirus affecting mammals, including humans
  • May present with either encephalitic or paralytic symptoms
  • Generally considered to be 100% fatal once symptoms present
  • Vaccine-preventable
  • System(s) affected: Central nervous system
  • Synonym(s): Hydrophobia (inability to swallow water)

Epidemiology

  • Present on all continents except Australia and Antarctica
  • >95% of human deaths related to rabies occur in Asia and Africa.
  • Bats are the most common reservoir in the United States.
  • Dogs are the most common reservoir worldwide.

Incidence
  • Estimated 55,000 deaths worldwide per year
  • Typically only 1 to 3 cases per year in the United States: 1/3 of those exposures occur outside of the United States
  • Predominant age: 40% of people worldwide bitten by suspected rabid animals are children <20 years of age.
  • Predominant sex: male = female

Etiology and Pathophysiology

  • Family Rhabdoviridae; genus Lyssavirus: bullet-shaped, enveloped, neurotropic virus
  • Transmission occurs mainly via bites from infected animals or when saliva from an infected animal comes in contact with an open wound or mucous membrane.
    • However, 60% of human cases of bat-variant virus in North America report no history of bat bite or scratch and 33% report no history of bat contact.
    • Although rare, there are reported cases of laboratory aerosolization and infection from transplanted organs.
  • The virus replicates in muscle tissue and binds to acetylcholine receptors at the neuromuscular junction.
    • The virus continues moving through nerves to the spinal cord where infection of the dorsal ganglia leads to pain. It rapidly multiplies in the brain and passes to the salivary glands where it is shed abundantly during the incubation period.

Risk Factors

  • Professions or activities with exposure to potentially infected (wild or domestic) animals (e.g., animal handlers, lab workers, veterinarians, cave explorers)
  • Travel to countries where canine rabies is endemic
  • Most U.S. cases are associated with bat exposure.
  • Internationally, rabies is widespread in both domestic and feral dogs.
  • Human-to-human transmission has occurred through transplantation of cornea, solid organs, and other tissues.

General Prevention

  • Pre-exposure vaccination
    • For high-risk groups (veterinarians, animal handlers, wildlife rangers, and certain laboratory workers)
    • Consider pre-exposure vaccination for travelers to areas (such as North Africa) that have increased risk of rabies from domestic animals.
  • Source control and avoidance
    • Immunization of dogs and cats has led to a dramatic decrease in U.S. cases since the 1950s.
    • Contact animal control and avoid approaching or handling wild (or domestic) animals exhibiting strange behaviors.
  • Post-exposure prophylaxis
    • Seek treatment promptly if bitten, scratched, or in contact with saliva from potentially infected animal.
    • Prevent infection by prompt post-exposure treatment.
    • Consider post-exposure prophylaxis for individuals in direct contact with bats.
    • Hospital contacts of patients infected with rabies do not require postexposure prophylaxis unless there has been exposure through mucous membranes or an open wound (including a bite) to saliva, cerebrospinal fluid (CSF), or brain tissue from the infected patient.
    • Hospitalized patients should be placed in contact isolation with gowns, gloves, goggles, and masks.

-- To view the remaining sections of this topic, please or --

Basics

Description

  • A rapidly progressive central nervous system (CNS) infection caused by a ribonucleic acid (RNA) rhabdovirus affecting mammals, including humans
  • May present with either encephalitic or paralytic symptoms
  • Generally considered to be 100% fatal once symptoms present
  • Vaccine-preventable
  • System(s) affected: Central nervous system
  • Synonym(s): Hydrophobia (inability to swallow water)

Epidemiology

  • Present on all continents except Australia and Antarctica
  • >95% of human deaths related to rabies occur in Asia and Africa.
  • Bats are the most common reservoir in the United States.
  • Dogs are the most common reservoir worldwide.

Incidence
  • Estimated 55,000 deaths worldwide per year
  • Typically only 1 to 3 cases per year in the United States: 1/3 of those exposures occur outside of the United States
  • Predominant age: 40% of people worldwide bitten by suspected rabid animals are children <20 years of age.
  • Predominant sex: male = female

Etiology and Pathophysiology

  • Family Rhabdoviridae; genus Lyssavirus: bullet-shaped, enveloped, neurotropic virus
  • Transmission occurs mainly via bites from infected animals or when saliva from an infected animal comes in contact with an open wound or mucous membrane.
    • However, 60% of human cases of bat-variant virus in North America report no history of bat bite or scratch and 33% report no history of bat contact.
    • Although rare, there are reported cases of laboratory aerosolization and infection from transplanted organs.
  • The virus replicates in muscle tissue and binds to acetylcholine receptors at the neuromuscular junction.
    • The virus continues moving through nerves to the spinal cord where infection of the dorsal ganglia leads to pain. It rapidly multiplies in the brain and passes to the salivary glands where it is shed abundantly during the incubation period.

Risk Factors

  • Professions or activities with exposure to potentially infected (wild or domestic) animals (e.g., animal handlers, lab workers, veterinarians, cave explorers)
  • Travel to countries where canine rabies is endemic
  • Most U.S. cases are associated with bat exposure.
  • Internationally, rabies is widespread in both domestic and feral dogs.
  • Human-to-human transmission has occurred through transplantation of cornea, solid organs, and other tissues.

General Prevention

  • Pre-exposure vaccination
    • For high-risk groups (veterinarians, animal handlers, wildlife rangers, and certain laboratory workers)
    • Consider pre-exposure vaccination for travelers to areas (such as North Africa) that have increased risk of rabies from domestic animals.
  • Source control and avoidance
    • Immunization of dogs and cats has led to a dramatic decrease in U.S. cases since the 1950s.
    • Contact animal control and avoid approaching or handling wild (or domestic) animals exhibiting strange behaviors.
  • Post-exposure prophylaxis
    • Seek treatment promptly if bitten, scratched, or in contact with saliva from potentially infected animal.
    • Prevent infection by prompt post-exposure treatment.
    • Consider post-exposure prophylaxis for individuals in direct contact with bats.
    • Hospital contacts of patients infected with rabies do not require postexposure prophylaxis unless there has been exposure through mucous membranes or an open wound (including a bite) to saliva, cerebrospinal fluid (CSF), or brain tissue from the infected patient.
    • Hospitalized patients should be placed in contact isolation with gowns, gloves, goggles, and masks.

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