HUMAN RABIES PREVENTION:PROPHYLAXIS MANAGEMENT: HUMAN RABIES PREVENTION: PROPHYLAXIS MANAGEMENT
Charles E. Rupprecht VMD, MS, PhD
Chief, Rabies Program
PRB/DVRD/NCZVED/CCID/CDC DEFINITION: DEFINITION Rabies is an acute, progressive encephalomyelitis
The case to fatality rate is the highest of any infectious disease
One of the oldest described diseases
The leading viral zoonosis as regards global public health significance ETIOLOGY: ETIOLOGY Rabies is caused by RNA viruses in the family Rhabdoviridae, genus Lyssavirus
The type species of the genus is Rabies Virus
At least other 6 other lyssavirus species or genotypes cause rabies
Recently, 4 new lyssaviruses from Eurasian bats have been described as putative species DISTRIBUTION: DISTRIBUTION Rabies is distributed on all continents (with the exception of Antarctica)
Several areas are considered ‘free’ of the disease, including many islands in Pacific Oceania
Globalization may threaten the disease-free status of many localities, due to the introduction of rabid animals RABIES HOSTS: RABIES HOSTS All warm-blooded vertebrates are susceptible to experimental infection
Mammals are the natural hosts of rabies
Reservoirs consist of the Carnivora (canids, skunks, raccoons, mongoose, etc.) and Chiroptera (bats) BURDEN: BURDEN More than ~55,000 human rabies deaths per year
Most occur in developing countries
Millions of human exposures per year
The domestic dog is the single most important animal reservoir
Wildlife important, especially in developed countries RABIES PATHOGENESIS: RABIES PATHOGENESIS Virus is transmitted via bite
Agents are highly neurotropic
Enter peripheral nerves
Centripetal travel by retrograde flow in axoplasm of nerves to CNS
Replicate in brain
Centrifugal flow to innervated organs, including the portal of exit, the salivary glands
Viral excretion in saliva RABIES DIAGNOSIS: RABIES DIAGNOSIS Based upon history of animal exposure and typical neurological clinical signs
Postmortem demonstration of viral antigen in CNS is gold standard
In humans, antemortem detection of virus or viral amplicons, antibodies, or antigens (sera, csf, saliva, nuchal biopsy)
CLINICAL STAGES: CLINICAL STAGES Incubation Period (range = ~<7 days to >6 years; average is ~4-6 weeks)
Prodromal Phase (Non-specific signs)
Acute Neurological Phase
Death (recovery from rabies?) RABIES RECOVERY?: RABIES RECOVERY?
Five historical human case recoveries, after vaccination, but before illness onset
Only one documented unvaccinated human survivor after clinical presentation RABIES IN THE USA: RABIES IN THE USA Human rabies uncommon (1-8 cases per year); ~ 20,000 – 40,000 human exposures per year
Approximately 7,000 – 10,000 animal rabies cases diagnosed per year
Dog rabies transmission eliminated
Wildlife hosts include raccoons, skunks, foxes, mongoose (Puerto Rico), and bats
Distributed in every state except Hawaii RABIES EXPOSURE: RABIES EXPOSURE Bite (common cause)
Non-bite (rarely causes rabies)
Contacts with blood, urine, feces, etc. are not considered exposure
Many scenarios, such as merely seeing a rabid animal, being in the same room, petting, etc., are not considered grounds for prophylaxis A small bat bite on a finger PROPHYLAXIS: PROPHYLAXIS Pre-exposure Vaccination
Postexposure Prophylaxis (PEP) PRE-EXPOSURE VACCINATION: PRE-EXPOSURE VACCINATION Provided to subjects at risk before occupational or vocational exposure to rabies
Subjects include diagnosticians, laboratory & vaccine workers, veterinarians, cavers, etc.
Simplifies postexposure management POSTEXPOSURE PROPHYLAXIS: POSTEXPOSURE PROPHYLAXIS Provided to subjects after rabies exposure
Consists of wound care, rabies immune globulin, and vaccine
If prompt and proper, survival virtually assured RABIES BIOLOGICALS: RABIES BIOLOGICALS Rabies Vaccines (for pre- and PEP)
Rabies immune globulin (only in PEP)
RABIES VACCINES: RABIES VACCINES Two Human Rabies Vaccines in USA:
Human Diploid Cell Vaccine Imovax® (HDCV)
Purified Chick Embryo Cell RabAvert® (PCEC)
RVA no longer available
Intradermal application no longer available in USA
RABIES IMMUNE GLOBULIN: RABIES IMMUNE GLOBULIN Two Human Rabies Immune Globulins in the USA:
Both supplied in vials at ~ 150 IU/ml
PRE-EXPOSURE VACCINATION: PRE-EXPOSURE VACCINATION Vaccine given on days 0, 7, and 21 or 28
Serology occurs every 6 months to 2 years (if remaining at risk)
If antibody titer not adequate, administer a single booster dose
If ever exposed, give a vaccine dose on days 0 and 3, regardless of titer POSTEXPOSURE PROPHYLAXIS: POSTEXPOSURE PROPHYLAXIS Wash lesions well with soap and water (tetanus booster ad hoc)
Infiltrate rabies immune globulin (20 IU/kg) into and around the margin of the bites
Administer vaccine on days 0,3,7,14, and 28 POSTEXPOSURE PROPHYLAXIS: POSTEXPOSURE PROPHYLAXIS Urgency rather than emergency, per se
Depends in part upon the animal species, exposure details, rapidity of diagnostic testing, and epidemiology of rabies in the local area
Consultation with knowledgeable public health officials should be routine ADVERSE REACTIONS: ADVERSE REACTIONS PEP should not be interrupted because of local or mild systemic adverse reactions
Use of anti-inflammatory, antihistaminic, and antipyretic agents suggested
Serious systemic, anaphylactic, or neuroparalytic reactions are rare (VAERS) CASE REPORTS: CASE REPORTS Defining true viral exposure (or not)
Management or diagnosis of the biting animal
Correction of errors in clinical delivery or schedules CASE REPORT #1: CASE REPORT #1 While jogging in upstate New York, a 55 yr old woman is bitten by her neighbor’s poorly supervised, vaccinated, elderly poodle (which is then restrained and held for observation)...
Are you concerned?
CASE REPORT #2: CASE REPORT #2 While working with a friend’s retriever in rural Mississippi, an experienced, 42 yr old dog trainer is bitten multiple times by the unvaccinated, unruly, and somewhat vicious puppy (which runs to the highway, is struck and killed by a speeding semi-tractor trailer truck, and subsequently buried)...
Do you suggest PEP?
CASE REPORT #3: CASE REPORT #3 While walking to work in downtown Seattle, a well intentioned 35 yr old lawyer receives a superficial scratch on the hand as she befriends a stray street kitten (which is never seen again)...
What do you recommend?
CASE REPORT #4: CASE REPORT #4 The ER resident is new, and gave 5 doses of RIG and only a single dose of rabies vaccine to a teenage Wisconsin camper, who awoke to find a bat in his rustic cabin this morning…
How would you now manage this case?
CASE REPORT #5: CASE REPORT #5 A San Francisco family brings in to your hospital their elderly relative, bitten by a dog on the outskirts of Beijing 2 weeks ago, carrying a village pharmacy script written in a local dialect, for follow-up PEP…
What would you do?
CASE REPORT #6: CASE REPORT #6 It is Friday before a 3 day weekend, when a 4 yr old toddler from Virginia presents with a skunk bite to the lower leg. Due to the holiday, diagnostic testing results may not be available for 5-7 days…
Would you wait until next week to consider PEP?
CASE REPORT #7: CASE REPORT #7 A 72 yr old farmer in Florida was bitten by a rabid bobcat. He appears for his 4th dose of HDCV on day 21, instead of day 14…
Do you restart PEP?
CASE REPORT #8: CASE REPORT #8 A 25 yr old Chicago native awakens to a rat bite on the foot, but the animal escapes from her apartment…
Is PEP warranted?
CASE REPORT #9: CASE REPORT #9 A 60 yr old animal shelter worker in Montana has a rabies virus antibody ELISA titer of ~1/5, 2 yr after primary pre-exposure vaccination with PCEC…
Does the patient require a booster?
CASE REPORT #10: CASE REPORT #10 A 31 yr old Michigan veterinarian relocates to Texas. Approximately 10 yr ago, he received the RVA vaccine in a pre-exposure setting, and has cut himself during a necropsy on a suspect gray fox…
Do you need to acquire RVA vaccine?
REFERENCES: REFERENCES Advisory Committee on Immunization Practices (ACIP), 1999 MMWR 48: RR-1
World Health Organization Expert Consultation on Rabies, Geneva, Switzerland, 2005, Tech Rep Ser 931:1-88
NASPHV Compendium of Animal Rabies Prevention & Control, 2007, MMWR 56:RR-3 QUESTIONS? : QUESTIONS?