Rabies

Table of Contents

Disease Information

(Human and Animal)

The virus that causes rabies is a rhabdovirus of the genus Lyssavirus.

Overview

Report Human Cases Immediately

Also known as: Hydrophobia and Lyssa

Responsibilities

  • Hospital: Report human cases immediately by phone
  • Infection Preventionist: Assess in-house exposures to hospitalized human cases
  • Lab: Report all human cases immediately by phone, animal positive cases report by phone or mail
  • Physician: Report human cases immediately by phone
  • Local Public Health Agency (LPHA): Assess case exposures and other potential human exposures

Iowa HHS
Disease Reporting Hotline: (800) 362-2736
Secure Fax: (515) 281-5698

A. Agent

The virus that causes rabies is a rhabdovirus of the genus Lyssavirus.

B. Clinical Description

Animal Rabies

Rabies is primarily a disease of the central nervous system. Animals with rabies can appear normal, meek (“dumb rabies”), or may be aggressive (“furious rabies”). Animals with furious rabies often exhibit aggressive or unusually excited behavior; they may excessively salivate and attack other animals or humans. Dumb rabies may be more difficult to detect; animals may seem tame, wounded, or dazed. These animals have been described as acting disoriented or suffering from some paralysis.  While these behaviors are commonly reported, an animal’s behavior is not a reliable indicator of whether it has rabies.

Human Rabies

Rabies is a fatal infection, which usually progresses over 2 – 21 days.  A prodromal phase, lasting 2 – 10 days, is characterized by pain and numbness/tingling at the site of the bite (present in 50% – 80% of cases), and nonspecific complaints such as fatigue, headache and fever. Behavioral changes may also be apparent, including apprehension, anxiety, agitation, irritability, insomnia and depression.  The prodromal phase is quickly followed by the neurologic phase, during which the patient may suffer disorientation and hallucinations; paralysis; episodes of terror and excitement; hydrophobia; hyperventilation; hypersalivation; and seizures. These symptoms are invariably followed by coma and death. Once symptoms have begun, there is usually no treatment or cure; prevention is the only tool.

Rabies should be considered in patients with signs or symptoms of encephalitis or myelitis, including autonomic instability, dysphagia, hydrophobia, paresis, and paresthesia, particularly if a nonspecific prodrome preceded the onset of these signs by three to four days. Progressive worsening of neurologic signs is characteristic of rabies and should be considered as a positive indicator for rabies. Laboratory tests to rule out common encephalitides (herpes, enteroviruses, arboviruses) should be performed. Negative results of these tests would increase the likelihood of rabies as the diagnosis. If a patient presents with symptoms similar to the ones described above, but the neurologic status does not change and the illness continues for longer than three weeks, rabies is unlikely as the diagnosis.

Positive Indicators for Rabies

  • Nonspecific prodrome prior to onset of neurologic signs
  • Neurologic signs consistent with encephalitis or myelitis
    • dysphagia
    • hydrophobia
    • paresis
  • Progression of neurologic signs
  • Negative test results for other etiologies of encephalitis

Negative Indicators for Rabies

  • Improvement or no change in neurologic status
  • Illness with = 2 to 3 week duration

C. Reservoirs

All species of mammals are susceptible to rabies infection. In 2014, 15 cases of animal rabies were reported in Iowa, which is slightly higher than the number in 2013. Rabies was identified most frquently in wildlife species, including 10 bats and 2 skunks. Two cases were diagnosed in cows and one in a cat. This data reflects only the tested animals that might have exposed humans or other domestic animals to rabies, and does not represent all rabid animals in Iowa.   See www.idph.state.ia.us/Rabies/Resources.aspx  for more information.

D. Modes of Transmission

Rabies is spread via the virus-laden saliva of an infected animal through a bite or saliva contact with mucous membranes or a fresh break in the skin. Breaks in the skin or mucous membrane exposure to nervous tissue (brain, spinal cord) of an infected animal also pose a transmission threat. Bites of some animals, such as bats, can inflict injury so minor that it goes undetected.  Airborne spread (for example, in a cave with many bats, or in a laboratory through rabies virus or specimens) is rare, but has been reported.  Rabies is not transmitted through contact with blood, urine, skunk spray, or feces of an infected animal.

Person-to-person spread has been documented after organs and corneas were transplanted from rabies infected individuals. Two non-laboratory-confirmed cases of person-to-person rabies transmission in Ethiopia have been described; the reported route of exposure in both cases was direct saliva contact (a bite and a kiss). 

E. Incubation period

Animal Rabies

Depending on the animal, the incubation period may vary from a few weeks to a few years, but is typically 1 - 3 months.

Human Rabies

The incubation period is usually 3 - 8 weeks, but can rarely range from as few as 9 days (although 9-day incubation periods have not been documented in the U.S. with native strains of rabies) to as many as 7 years. Less than 1% of human cases have an incubation period longer than 6 months. The incubation period is typically related to the site of exposure; e.g., the incubation period is usually shorter if the virus is inoculated closer to the central nervous system or in a highly innervated area. The incubation period also typically depends on exposure severity (more virus exposure results in a shorter incubation period) and the age of the exposed person (younger age generally results in a shorter incubation period). 

F. Period of Communicability or Infectious Period

Animal Rabies

Animals are not infectious until virus is present in their saliva, which happens around the time of clinical onset of illness. Dogs, cats and ferrets may shed virus in their saliva for 3 – 7 days before the onset of clinical signs, and continue to shed virus until death. The shedding/communicability period for most wild animals has not been determined, although it appears that skunks may shed virus up to 18 days before death. Carcasses of animals with rabies may contain infectious virus, depending on temperature and environmental conditions. Rabies virus may persist in a frozen carcass for many weeks; however drying and sunlight rapidly deactivate rabies virus. A dried carcass or dried saliva does not contain live rabies virus.

Human Rabies

The period during which a patient is potentially infectious may begin up to 1 week before symptom onset and last until death. Saliva is considered potentially infectious, as are cerebrospinal fluid and organs (although viral concentrations in humans are 3 – 4 times lower than in dogs).

G. Epidemiology

Animal rabies

Animal rabies exists in most parts of the world. In the United States, Hawaii is the only state that has never reported an indigenously-acquired rabies case in humans or animals. In 2010, wild animals accounted for approximately 92% of reported cases of animal rabies in the U.S. Nationally, raccoons continue to be the most frequently reported rabid wildlife species (36.5% of all animal cases in 2010), followed by skunks (23.5%), bats (23.2%), foxes (6.6%), and other wild animals including rodents and lagomorphs (1.9%).

In the U.S., domestic species accounted for 8% of all rabid animals reported in 2010. The number of reported rabid domestic animals increased among cats and decreased among dogs, horses, sheep, and goats during 2010. In 2010, cases of rabies in cats increased 1.0% compared with the number reported in 2009. The number of rabies cases reported in cats is routinely 3-4 times that of rabies reported in cattle or dogs. In 2010 approximately 1.1% of cats and 0.3% of dogs tested for rabies were found positive.  

Human Rabies

Worldwide an estimated 35,000–40,000 human rabies deaths occur each year. The vast majority of these deaths occur in developing countries. In the United States from 1995 through 2008, there were 49 human cases, of which 48 were fatal.  Four cases were the result of solid tissue organ transplantation; 30 cases were associated with bat variants; one was associated with the raccoon variant; one was associated with the fox variant; and eight were associated with the canine variant. The most recent human cases of rabies in Iowa occurred in 1951 and 2002. The 2002 case was caused by the bat strain of rabies virus.

H. Additional Information

The Council of State and Territorial Epidemiologists (CSTE) surveillance case definitions for Rabies can be found at:  www.cdc.gov/osels/ph_surveillance/nndss/phs/infdis.htm#top

CSTE case definitions should not affect the investigation or reporting of a case that fulfills the criteria in this chapter. (CSTE case definitions are used by the state health department and the CDC to maintain uniform standards for national reporting.)

Fact Sheets and Forms

Programs for Uninsured and Underinsured Patients

Patient assistance programs that provide medications to uninsured or underinsured patients are available for rabies vaccine and Immune globulin.

Sanofi Pasteur’s Patient Assistance Program (providing Imogam ® Rabies-HT and Imovax ® Rabies as well as other vaccines) is now administered through the Franklin Group. A healthcare professional or patient can either contact the Franklin Group directly, or call the customer service team (1-800-VACCINE) who will transfer them to the Franklin Group. The Franklin Group will review the application against the eligibility criteria. For more information about the program or to request an application, please contact the Sanofi Pasteur, Inc. Patient Assistance Program (Franklin Group) at 1 (866) 801-5655.

Novartis’ Patient Assiatance Program for RabAvert ® is managed through RX for Hope and can be accessed at 800-244-7668. Instructions and request forms are also available at the Rx for Hope website RabAvert Patient Assistance Program .

References

CDC. Human Rabies Prevention—United States, 2008, Recommendations of the Advisory Committee on Immunization Practices (ACIP), MMWR. May 23, 2008; 57:RR-03.

Heymann D., ed. Control of Communicable Diseases Manual, 20th Edition. Washington, DC: American Public Health Association, 2015.

Compendium of Animal Rabies Control, MMWR, April 18, 2008; 57:RR02

Additional Resources

Iowa Department of Public Health – Rabies Resources:   www.idph.state.ia.us/Rabies/ 
CDC Resources:       www.cdc.gov/mmwr/preview/mmwrhtml/rr5902a1.htm
www.cdc.gov/mmwr/preview/mmwrhtml/rr57e507a1.htm?s_cid=rr57e507 _e%0d%0a

Compendium for animal rabies control:   www.nasphv.org/Documents/RabiesCompendium.pdf

Consultants

Iowa Department of Public Health
During regular business hours call:  (800) 362-2736
After hours call:  (515) 323-4360

Laboratories

University of Iowa State Hygienic Laboratory (SHL)
Oakdale Campus
University of Iowa
Iowa City, IA 52242
Tel:  (319) 335-4500 or (800) 421-4692 (answered all hours)
https://www.shl.uiowa.edu/testmenu/formgenerator.xml
 
Iowa State University Veterinary Diagnostic Lab (VDL)
College of Veterinary Medicine
Iowa State University
Ames, IA 50011
Tel:  (515) 294-1950 or after hours (515) 290-1969 (Veterinary Teaching Hospital)
https://vetmed.iastate.edu/vdl/submissions/guidelines/rabies

Laboratories that perform the Rapid Fluorescent Focus Inhibition Test

(the CDC recognized test for assessing human antibody levels)

Interpretation:  A titer of 1:5 is considered adequate.
Shipping Information:  Please send the following information with your specimen:

  • Address of person or institution responsible for receiving the results and billing information.
  • Complete vaccination history if possible.
  • All serum samples that are potentially pathogenic to humans should be labeled or marked with red tape or sticker.Send samples to (any one of the following):

K-State Rabies Laboratory
Manhattan/K-State Innovation Center
2005 Research Park Circle
Manhattan, KS 66502
Main telephone:  (785) 532-4483
Fax:  (785) 532-4522 or (785) 532-4474
Email: rabies@vet.k-state.edu
Web address: www.vet.ksu.edu/rabies

Atlanta Health Associates
309 Pirkle Ferry Road, Suite D300;
Cumming, GA 30040
(770) 205-9091 or (800) 717-5612
FAX: (770) 204-9021
Web address: www.atlantahealth.net/

Auburn University College of Veterinary Medicine
Note: Only animal specimens tested.
Dept. of Pathobiology, Virology Lab
261 Greene Hall
Auburn University, AL 36849-5519
(334) 844-2659 
www.vetmed.auburn.edu/diagnostics

Current Licensed Rabies Immunizing Products for Humans:

Human Rabies Vaccine

Imovax TM  Rabies
Human diploid cell vaccine
Sanofi Pasteur Inc
Box 187 Discovery Dr
Swiftwater, PA 18370-0187
(800) 822-2463
(570) 839-7187
fax: (570) 839-0955
www.sanofipasteur.us

RabAvert TM
Purified chick embryo cell culture
Novartis
4560 Horton Street
Emeryville, CA 94608-2916
(800) 244-7668
fax: (510)923-3434
MN # (510) 655-8730
www.rabavert.com

Human Rabies Immune Globulin (HRIG)

Hyperrab
Talecris Biotherapeutics Inc
PO Box 110526
4101 Research Commons
79 T. W. Alexander Dr
Research Triangle Park, NC 27709
(800) 243-4153 
www.talecrisbiousa.com

Imogam Rabies
Sanofi Pasteur Inc.
Box 187 Discovery Dr
Swiftwater, PA 18370-0187
(800) 822-2463
(570) 839-7187
fax: (570) 839-0955
www.sanofipasteur.us