Rabies Topic Disucssion

Background Signs/Symptoms
• Definition • After a rabies exposure, the rabies virus must travel to the brain before it can cause symptoms. This time
o Rabies (Lyssavirus rabies) is a severe, viral disease that primarily affects the central between exposure and the appearance of symptoms is the incubation period. It may last for weeks to
nervous system and can lead to severe brain disease and death if medical care is not months. The incubation period may vary based on:
o The location of the exposure site (how far away it is from the brain),
received before symptoms start.
o The severity of exposure (how much virus entered the body),
o Rabies virus (RABV) can affect any mammal. It can be spread to people and pets o The age of the patient (younger children may have shortened incubation periods), and
through broken skin from the bites and scratches of an infected animal. o Whether the person had ever received a rabies vaccine.
• Incidence • The first symptoms of rabies, called prodrome, are like the flu, including weakness, discomfort, fever, or
o 60,000 human deaths every year worldwide, particularly in Asia and Africa where dog headache and may last for several days.
rabies is endemic. • Severe disease can appear within two weeks of the first symptoms when the rabies virus causes brain
dysfunction, including encephalitis.
o In the United States there are usually only 1 or 2 human cases per year. The most
o Furious rabies which occurs in 80% of cases and is characterized by hallucinations, bizarre behavior,
common source of human rabies in the United States is bats.
anxiety, agitation, biting, hydrophobia, and autonomic dysfunction
o Zero human rabies cases due to bites by rodents have been reported and RABV is very o Paralytic rabies which occurs in 20% of cases is characterized by progressive paralysis which typically
uncommon in rodents. starts at the site of the bite and spreads throughout the body
o In Wyoming, rabies is mostly found in bats and skunks. Bat bites are not always visible, Pathophysiology
anyone who has direct contact with a bat or who wakes up with a bat in their room should o Virus enters into the body (typically from a bite through a break in the skin)
immediately contact emergency services. o Virus replicates in muscles (causes first specific clinical symptom, neuropathic pain at the bite site)
o As of 3/31/2025 there have been 54 total exams for rabies in Wyoming with zero positive o Then infects the nerves that innervate the muscle spindles & moves into the peripheral neurons
tests. o Virus spreads via peripheral nerves to the spinal cord
o After reaching the spinal cord the virus spreads throughout the CNS
o In some parts of the world, like certain countries in Africa and Asia, dogs are the most
• Once clinical signs of rabies appear, the disease is nearly always fatal, and treatment is typically supportive.
likely animal to spread rabies. Because in these countries, most dogs do not get a rabies
Death is due to neuronal dysfunction at the molecular level and occurs an average of 18 days after onset of
shot. symptoms.

Treatment Treatment
• There is no known effective treatment for rabies and although rabies is nearly always a fatal disease in humans, it can • Rabies Immune Globulin (HRIG)
be successfully prevented if post-exposure prophylaxis (PEP) treatment is started promptly after exposure and before o Purified antirabies immunoglobulins from serum of hyperimmunized donors
symptoms develop. o Dose = 20 IU/kg IM x 1 dose on day 0 (recommended for all age groups, including children)
• 2 main immunization strategies: o Give entire dose into the bite area if anatomically possible, otherwise inject intramuscularly at a site distant from
o Pre-exposure prophylaxis (PrEP): vaccination where the vaccine was given.
o Post-exposure prophylaxis (PEP): vaccination and immunoglobulins • If the wound is small and on a distal extremity (e.g., a finger, or toe), use clinical judgement to decide how much
• Preexposure Prophylaxis (PrEP), indications for rabies vaccine include persons whose job places them at high risk HRIG to inject to avoid complications (e.g., ischemia) due to localized swelling of the finger or fingers.
for rabies exposure, such as veterinarians, animal handlers, laboratory workers in rabies research, cavers, wildlife • If the wounds are extensive, do not exceed the dose-appropriate volume of HRIG. If the indicated volume is
officers where animal rabies is common, and anyone who handles bats. Travelers who will be in a country where inadequate to inject into all wounds, you can dilute the HRIG with normal saline to ensure sufficient volume to
there is a constant threat of rabies, which stay is likely to extend beyond 1 month, and who many do not have inject all wounds. The one exception is the newer more concentrated version of HRIG (HyperRAB 300 IU/mL),
readily available medical services (e.g., Peace Corp workers and missionaries) should be considered for preexposure which requires using D5W as the diluent.
prophylaxis. o Human Rabies Immunoglobulin (HRIG):
o PrEP vaccination is a three-dose series of 1 mL IM on days 0 and 7 and once between days 21 and 3 years • Human immunoglobulin – KEDRAB 150 IU/mL saline diluent
later. • Human immunoglobulin – HyperRAB S/D 150 IU/mL saline diluent
o Individuals with ongoing risk of exposure—either continuous risk or individuals with frequent exposures—should • Human immunoglobulin – HyperRAB 300 IU/mL dextrose 5% in water (D5W)*** requires lower volumes to
undergo serologic testing every 6 months and 2 years, respectively, to monitor rabies antibody concentrations. administer the recommended dose of 20 IU/kg
o A booster dose is recommended if the complete virus neutralization is less than 1:5 serum dilution. • Rabies Virus Vaccine (4 or 5 doses)
• Postexposure Prophylaxis (PEP), is medical care after a rabies exposure. o 1 mL administered IM on days 0, 3, 7, 14,
o For people who have never had a rabies vaccine, rabies PEP consists of:
• And day 28 if immunosuppressed
▪ wound washing with soap and/or virucidal agents, which may reduce the risk of rabies by 90%,
o Administer in the deltoid muscle
▪ a dose of human rabies immune globulin (HRIG) administered into and around the wound, after o Vaccines:
exposure, neutralizing RABV at the wound site,
• Human diploid cell vaccine (HDCV) – Imovax (>2.5 IU of rabies antigen)
▪ and a series of 4 or 5 rabies vaccines, the first given immediately after exposure, induces antibodies
that lower the risk of RABV entering peripheral nerves. Then, it includes a dose of vaccine given again • Purified chick embryo cell vaccine (PCECV) – RabAvert (>2.5 IU of rabies antigen)
on days 3, 7, and 14 after the first dose and day 28 if immunosuppressed. • The shelf-life of these vaccines is >3 years, provided they are stored at 2-8*C and protected from sunlight.
o Rabies deaths occur mainly in those who cannot access timely and effective PEP. • HRIG provides passive immunization by neutralizing RABV at the wound site before the immune system can respond to
o PEP is nearly 100% effective if administered promptly. the vaccine by producing viral neutralizing antibodies (VNAs). HRIG should be administered only once, preferably at, or
o For people who have been previously vaccinated AND have adequate antibody titers: as soon as possible after, the initiation of PEP. HRIG should not be given after day 7 following the first rabies vaccine
▪ wound washing, dose because circulating VNAs will have begin to appear.
▪ no immune globulin, • Because patients are getting immunoglobulin that can stunt the body’s own production they need to get more vaccine in
▪ give 2 booster doses of vaccine (on days 0 and 3). order to create the necessary antibodies.

Tips to Prevent Rabies in You and in Your Pets Reference

• Do not touch or feed wild or stray animals. • Jackson AC. Treatment of rabies. UpToDate. Updated March 07, 2025. Accessed April 18, 2025.
https://www.uptodate.com/contents/treatment-of-rabies
• Treat animal bites with soap and water and contact a medical professional • Rabies. Infectious Disease Epidemiology Unit. Wyoming Department of Health. 2025. Accessed April
immediately. Call your veterinarian if you believe your pet may have come into 18, 2025. https://health.wyo.gov/publichealth/infectious-disease-epidemiology-unit/disease/rabies/
• Rabies Information. Wyoming State Veterinary Laboratory. Updated March 31, 2025. Accessed April
contact with a rabid animal. 18, 2025. https://www.uwyo.edu/wyovet/client-services/rabies-information.html
• People waking to find a bat in their room or a child’s room should contact a • Rabies. U.S. Centers for Disease Control and Prevention. Accessed April 18, 2025.
medical professional immediately. Call local animal control. https://www.cdc.gov/rabies/index.html
• Hayney MS. Vaccines and Immunoglobulins. In: DiPiro JT, Yee GC, Haines ST, Nolin TD, Ellingrod
• Vaccinate dogs, cats, ferrets, horses and other selected livestock for rabies
VL, Posey L. eds. DiPiro’s Pharmacotherapy: A Pathophysiologic Approach, 12th Edition. McGraw Hill;
and keep vaccinations up to date. 2023. Accessed April 18, 2025. https://accesspharmacy-mhmedical-
o Dogs and cats required (1- or 3-year vaccine) com.proxy.hsl.ucdenver.edu/content.aspx
o Livestock in areas of increasing rabies • Rabies vaccines: WHO position paper – April 2018. Weekly Epidemiological Record. 26:202-219.
Published April 20, 2018. Accessed April 28, 2025.
• Select humans at high risk of exposure should also get vaccinated: https://iris.who.int/bitstream/handle/10665/272372/WER9316-201-219.pdf?sequence=1
o Veterinarians
o Lab workers using rabies virus
o Spelunkers
o Travelers to areas of high dog rabies