eMedicine Specialties > Pediatrics: General Medicine > Infectious Disease

Rabies

Author: Donna J Fisher, MD, Assistant Professor, Department of Pediatrics, Division of Pediatric Infectious Diseases, Tufts University School of Medicine and Baystate Children's Hospital, Baystate Medical Center
Contributor Information and Disclosures

Updated: Oct 9, 2008

Introduction

Background

Rabies is a viral infection of the central and peripheral nervous systems that causes encephalitis with or without paralysis; it is virtually uniformly fatal.

Epidemiology and transmission

Bat (avian) rabies appears to be widespread in the 49 continental states. Bat rabies has been implicated in most human rabies cases acquired domestically in the United States during the last 25 years.1 Cases of rabies have been reported in humans exposed to aerosols of bat guano during recreational caving or to aerosolized laboratory strain virus. Recently, rabies has occurred secondary to virus transmission from infected transplanted solid organs in the United States.2,3 Statistics compiled by the Centers for Disease Control and Prevention (CDC) in the United States confirm that most human deaths from rabies not associated with foreign travel are from bat strains of rabies.4,5

In the United States, terrestrial rabies is most common in raccoons on the eastern coast and in skunks, foxes, coyotes, and dogs on the Texas-Mexico border. Canine rabies and bat rabies are significant problems in Mexico and around the world.

Five antigenic variants of rabies strains are recognized in the United States. The single raccoon strain is the predominant strain (see Media file 1).6,7 A single case of human rabies has resulted from the raccoon rabies strain in the United States.8

The only rodent in the United States that can carry rabies long enough to transmit to humans is the groundhog. Other small rodents (eg, squirrels, chipmunks, rats, mice) and lagomorphs (eg, rabbits, hares) usually die before being able to transmit rabies virus to humans, and human disease has never been transmitted by these mammals.

Domestic animals usually succumb to the virus strain predominant in their geographic region. Cats are the most common domestic animals reported by health departments as being rabid because of the high number of unvaccinated strays with possible contacts with bats and other mammals.9,10

Since 1980, most endemic rabies cases in humans in the United States have been associated with bat strains. Other cases have been associated with dog or animal bites in travelers returning from abroad, especially in countries where wild canine rabies is endemic. In other countries, canines are the most common source of rabies. Other animals, such as mongooses, jackals, ferrets, and domestic farm animals, may be common sources. Human-to-human transmission has only occurred with corneal and other organ transplants.3,2  Transmission of virus in saliva through mucous membranes, open wounds, or scratches is possible but rarely documented.

Rabies-free areas of the world are recognized. The island nations of the Caribbean are free of terrestrial rabies but may have bat rabies.11 Updates of this information can be found through the World Health Organization (WHO) and the CDC.

Pathophysiology

When the rabies virus enters muscles, it replicates locally and is then transported through peripheral sensory nerves to the spinal ganglia, where it replicates and travels up the spinal cord to the brain. The virus migrates to the gray matter of the brain and predominates in the neurons of the limbic system, midbrain, and hypothalamus. Efferent nerves transport virus to the acinar glands of the submaxillary salivary glands, where it achieves high concentrations.12

This transit time is presumably shorter if the initial wound is severe with a high load of virus and is proximal to the head.13,14

The reported incubation period in human beings has ranged from as short as 5 days to as long as 7 years; average incubation is 1-3 months prior to onset of symptoms. In rare cases, human rabies with an extended incubation period (2-7 y) has been reported.15,16

Frequency

United States

During 1990-1998, 22 cases of human rabies were reported in the United States. Potential exposures are not uncommon in the United States; an estimated 20,000-30,000 people per year receive treatment for potential rabies exposures. Exact exposures can only be determined if an animal is submitted for testing.1,17

International

Worldwide, endemic countries with wild animal vectors may have death rates as high as 40,000-50,000 per year (eg, Asia, Africa).

Mortality/Morbidity

Rabies is 100% fatal if postexposure treatment is not administered. A single survivor who was treated with an intensive care protocol to induce a controlled coma has been reported in the United States.18 Since then, others have tried to repeat use of this intervention without success.19

Race

No racial predilection is observed.

Sex

Encounters with rabid animal vectors may be increased in males, who may have greater contact in certain geographic areas. Evidence to support this is found in data on dog bites, which are observed more frequently in males than females.

Age

No age predilection is noted.

Clinical

History

  • Identify the following in any suspected case of rabies virus exposure:
    • The nature of the interaction with the animal (eg, provoked attack or unexpected)
    • Strange animal behavior (eg, nocturnal animal out during the daytime)
    • Vaccination status of the animal for rabies9 (See Other Tests.)
  • The 2 forms of rabies vary in nature of presentation between illness in the animal and possible human cases. Both forms progress to paralysis of pharyngeal and respiratory muscles, seizures, and coma with death in 1-3 weeks.
    • Most common in humans is the furious form with classic symptoms of paresthesias at the site of the bite, hypersalivation, and hydrophobia, including spasms and contractions of the neck muscles. This form is also common in cats.
    • Many other animals, including bats, exhibit dumb rabies (paralytic form).

Physical

Include the following in any examination of a patient who has been bitten by an animal:

  • Localization and documentation of the extent of the wound
  • Evidence of secondary complications, such as bacterial superinfection and tissue destruction
  • Neurologic examination of a patient with rabies - May reveal altered mental status, anxiety, hyperactivity, and bizarre behaviors with interspersed calm periods
  • Examination for autonomic instability -Hypertension, hypersalivation, hyperthermia, hyperventilation

Causes

  • Rabies is caused by the rabies virus, of the genus Lyssavirus and family Rhabdoviridae.
  • The bullet-shaped RNA virus has 3 major components: surface glycoprotein (G protein), outer envelope protein (M or matrix protein), and nucleocapsid.
  • Rabies virus is transmitted by bite or saliva of an infected mammal.
  • Any mammal can carry and potentially transmit the virus, but carnivorous species and bats are usually the agents of transmission.

More on Rabies

Overview: Rabies
Differential Diagnoses & Workup: Rabies
Treatment & Medication: Rabies
Follow-up: Rabies
Multimedia: Rabies
References
[ CLOSE WINDOW ]

References

  1. Messenger SL, Smith JS, Rupprecht CE. Emerging epidemiology of bat-associated cryptic cases of rabies in humans in the United States. Clin Infect Dis. Sep 15 2002;35(6):738-47. [Medline].

  2. Srinivasan A, Burton EC, Kuehnert MJ, et al. Transmission of rabies virus from an organ donor to four transplant recipients. N Engl J Med. Mar 17 2005;352(11):1103-11. [Medline]. [Full Text].

  3. Centers for Disease Control and Prevention. Investigation of rabies infections in organ donor and transplant recipients--Alabama, Arkansas, Oklahoma, and Texas, 2004. MMWR Morb Mortal Wkly Rep. Jul 9 2004;53(26):586-9. [Medline].

  4. Centers for Disease Control and Prevention. Human death associated with bat rabies--California, 2003. MMWR Morb Mortal Wkly Rep. Jan 23 2004;53(2):33-5. [Medline].

  5. Pape WJ, Fitzsimmons TD, Hoffman RE. Risk for rabies transmission from encounters with bats, Colorado, 1977- 1996. Emerg Infect Dis. May-Jun 1999;5(3):433-7. [Medline].

  6. Blanton J D, Hanlon CA, Rupprecht CE. Rabies surveillance in the United States during 2006. J Am Vet Med Assoc. Aug 15 2007;231(4):540-56. [Medline].

  7. Wyatt JD, Barker WH, Bennett NM, Hanlon CA. Human rabies postexposure prophylaxis during a raccoon rabies epizootic in New York, 1993 and 1994. Emerg Infect Dis. May-Jun 1999;5(3):415-23. [Medline].

  8. Centers for Disease Control and Prevention (CDC). First human death associated with raccoon rabies--Virginia, 2003. MMWR Morb Mortal Wkly Rep. Nov 14 2003;52(45):1102-3. [Medline].

  9. Compendium of animal rabies prevention and control, 2008: National Association of State Public Health Veterinarians, Inc. (NASPHV). MMWR Recomm Rep. Apr 18 2008;57:1-9. [Medline]. [Full Text].

  10. Moore DA, Sischo WM, Hunter A, Miles T. Animal bite epidemiology and surveillance for rabies postexposure prophylaxis. J Am Vet Med Assoc. Jul 15/ 2000;217(2):190-4. [Medline].

  11. Nel LH, Markotter W. Lyssaviruses. Crit Rev Microbiol. 2007;33(4):301-24. [Medline].

  12. Baer GM. The Natural History of Rabies. Boston, MA: CRC Press; 1991.

  13. Mrak RE, Young L. Rabies encephalitis in humans: pathology, pathogenesis and pathophysiology. J Neuropath Exp Neurol. 1994;53(1):1-10. [Medline].

  14. Tsiang H. Pathophysiology of rabies virus infection of the nervous system. Adv Virus Res. 1993;42:375-412. [Medline].

  15. Fisher DJ. Epidemiology and prevention of rabies. Curr Probl Pediatr. Nov-Dec 1995;25(10):304-13. [Medline].

  16. Fishbein DB, Robinson LE. Rabies. N Engl J Med. Nov 25 1993;329(22):1632-8. [Medline].

  17. Rupprecht CE, Gibbons RV. Clinical practice. Prophylaxis against rabies. N Engl J Med. Dec 16 2004;351(25):2626-35. [Medline].

  18. Willoughby RE, Tieves KS, Hoffman GM, et al. Survival after treatment of rabies with induction of coma. N Engl J Med. Jun 16 2005;352(24):2508-14. [Medline]. [Full Text].

  19. McDermid RC, Saxinger L, Lee B, et al. Human rabies encephalitis following bat exposure: failure of therapeutic coma. CMAJ. Feb 26 2008;178(5):557-61. [Medline].

  20. Manning SE, Rupprecht CE, Fishbein D, et al. Human rabies prevention--United States, 2008: recommendations of the Advisory Committee on Immunization Practices. MMWR Recomm Rep. May 23 2008;57:1-28. [Medline]. [Full Text].

  21. Goldstein EJ. Current concepts on animal bites: bacteriology and therapy. Curr Clin Top Infect Dis. 1999;19:99-111. [Medline].

  22. Moran GJ, Talan DA, Mower W, et al. Appropriateness of rabies postexposure prophylaxis treatment for animal exposures. Emergency ID Net Study Group. JAMA. Aug 23-30 2000;284(8):1001-7. [Medline].

  23. Dandoy S, Scanlon F. Teaching kids about rabies. Am J Public Health. Mar 1999;89(3):413-4. [Medline].

  24. Murray KO, Arguin PM. Decision-based evaluation of recommendations for preexposure rabies vaccination. J Am Vet Med Assoc. Jan 15 2000;216(2):188-91. [Medline].

  25. Fescharek R, Schwarz S, Quast U, et al. Postexposure rabies prophylaxis: when the guidelines are not respected. Vaccine. Dec 1991;9(12):868-72. [Medline].

  26. Fisher DJ. Resurgence of rabies. A historical perspective on rabies in children. Arch Pediatr Adolesc Med. Mar 1995;149(3):306-12. [Medline].

  27. Committee on Infectious Diseases, American Academy of Pediatrics. 2006 Red Book - Report of the Committee on Infectious Diseases. 27. Elk Grove, IL: American Academy of Pediatrics; 2006:552-9.

  28. Chutivongse S, Wilde H, Benjavongkulchai M, et al. Postexposure rabies vaccination during pregnancy: effect on 202 women and their infants. Clin Infect Dis. Apr 1995;20(4):818-20. [Medline].

  29. Arya SC, Agarwal N. Assessing the safety of post-exposure rabies immunization in pregnancy. Hum Vaccin. Sep-Oct 2007;3(5):155; author reply 155. [Medline].

  30. Abazeed ME, Cinti, S. Rabies prophylaxis for pregnant women. Emerg Infect Dis. Dec 2007;13(12):1966-7. [Medline].

  31. Wilde H, Tipkong P, Khawplod P. Economic issues in postexposure rabies treatment. J Travel Med. Dec 1999;6(4):238-42. [Medline].

[ CLOSE WINDOW ]

Further Reading

[ CLOSE WINDOW ]

Keywords

rabies, terrestrial rabies, hydrophobia, mad dog disease, bat rabies, avian rabies, paralytic rabies, dumb rabies, furious rabies, rabies virus, rhabdovirus, Lyssavirus, Rhabdoviridae, encephalitis, raccoon bite, bat bite, paralysis, altered mental status, anxiety, hyperactivity, hypertension, hypersalivation, hyperthermia, hyperventilation

[ CLOSE WINDOW ]

Contributor Information and Disclosures

Author

Donna J Fisher, MD, Assistant Professor, Department of Pediatrics, Division of Pediatric Infectious Diseases, Tufts University School of Medicine and Baystate Children's Hospital, Baystate Medical Center
Donna J Fisher, MD is a member of the following medical societies: American Academy of Pediatrics, American Society for Microbiology, Infectious Diseases Society of America, and Pediatric Infectious Diseases Society
Disclosure: Nothing to disclose.

Medical Editor

Rosemary Johann-Liang, MD, Medical Officer, Infectious Diseases and Pediatrics, Division of Special Pathogens and Immunological Drug Products, Center for Drug Evaluation and Research, Food and Drug Administration
Rosemary Johann-Liang, MD is a member of the following medical societies: American Academy of Pediatrics, American Medical Association, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

Pharmacy Editor

Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine
Disclosure: Pfizer Inc Stock Investment from broker recommendation; Avanir Pharma Stock Investment from broker recommendation

Managing Editor

Leslie L Barton, MD, Professor, Program Director, Department of Pediatrics, University of Arizona School of Medicine
Leslie L Barton, MD is a member of the following medical societies: American Academy of Pediatrics, Association of Pediatric Program Directors, Infectious Diseases Society of America, and Pediatric Infectious Diseases Society
Disclosure: Nothing to disclose.

CME Editor

Robert W Tolan Jr, MD, Chief, Division of Allergy, Immunology and Infectious Diseases, The Children's Hospital at Saint Peter's University Hospital; Clinical Associate Professor of Pediatrics, Drexel University College of Medicine
Robert W Tolan Jr, MD is a member of the following medical societies: American Academy of Pediatrics, American Medical Association, American Society for Microbiology, American Society of Tropical Medicine and Hygiene, Infectious Diseases Society of America, Pediatric Infectious Diseases Society, Phi Beta Kappa, and Physicians for Social Responsibility
Disclosure: GlaxoSmithKline Honoraria Speaking and teaching; MedImmune Honoraria Consulting; MedImmune Honoraria Speaking and teaching; Merck Honoraria Speaking and teaching; Novartis Honoraria Speaking and teaching; sanofi pasteur Grant/research funds Unrestricted research grant; sanofi pasteur  Consulting; sanofi pasteur Honoraria Speaking and teaching; Tap Honoraria Speaking and teaching

Chief Editor

Russell W Steele, MD, Head, Division of Pediatric Infectious Diseases, Ochsner Children's Health Center; Clinical Professor, Department of Pediatrics, Tulane University School of Medicine
Russell W Steele, MD is a member of the following medical societies: American Academy of Pediatrics, American Association of Immunologists, American Pediatric Society, American Society for Microbiology, Infectious Diseases Society of America, Louisiana State Medical Society, Pediatric Infectious Diseases Society, Society for Pediatric Research, and Southern Medical Association
Disclosure: None None None

 
 
HONcode

We subscribe to the
HONcode principles of the
Health On the Net Foundation

All material on this website is protected by copyright, Copyright© 1994- by Medscape.
This website also contains material copyrighted by 3rd parties.

DISCLAIMER: The content of this Website is not influenced by sponsors. The site is designed primarily for use by qualified physicians and other medical professionals. The information contained herein should NOT be used as a substitute for the advice of an appropriately qualified and licensed physician or other health care provider. The information provided here is for educational and informational purposes only. In no way should it be considered as offering medical advice. Please check with a physician if you suspect you are ill.