Lecture 3 - Rabies (me created)

Susceptibility of rabies?

• all mammals believed to be susceptible

• Bats: rabid bats were found in 50 jurisdictions in 2021

• Wild terrestrial carnivores: Raccoons, skunks, foxes

• Wild animals: Rodents not considered reservoirs and lagomorphs rarely infected

• Dogs, Cats, ferrets

why are rodents not usually carriers of Rabies?

something that bites a rodent usually kills the rodent and they often die rapidly so dont have living rodents with rabies

what is important with dogs, cats, ferrets with rabies?

• US has been declared free of K9 rabies virus variant transmission (misleading though b/c dog to dog bites rare but dog to human still occur)

• Since 2000, more cats than dogs are diagnosed with rabies

where are rabies raccoons highly prevalent?

all across east coast

rabies skunk distribution?

midwest states and mostly CA

rabies fox distribution?

South Arizona and Parts of Alaska

Rabies mongoose distribution?

carribbean

transmission and incubation of rabies?

• dogs, cats, ferrets shed virus for a few days prior to and during clinical signs

• incubation period is highly variable (3-12 weeks in domestic animals (range several days to 6 months)

• Incubation periods >1 year have been reported in humans

Rabies transmission?

dogs usually shed rabies virus in their saliva for up to 5-10 days before clinical signs develop

clinical presentation of rabies - animals?

• highly variable: inappetance, dysphagia, cranial nerve deficits, abnormal behavior, ataxia, paralysis, altered vocalization seizures

• case definition: requires lab confirmed by: positive direct fluorescent antibody test or isolation of rabies virus

• progression to death is rapid

• no effective rabies antiviral drugs

animal to human exposures - 2 major categories?

Bite and non-bite

animal to human exposures?

• indirect contact does not constitute rabies exposure

• bat exposures deserve special consideration (any direct contact)

human to human exposures

• organ transplantation has resulted in 16 rabies cases (8 corneas, 7 solid organs, 1 vascular tissue graft)

• no other human-to-human transmission is known

• caring for a human rabies patient is not an exposure; unless bite or saliva into an open wound occurred

what 2 vaccines are licensed for humans against rabies?

Human diploid cell vaccine (HDCV) and Purified chick embryo cell vaccine (PCECV)

how do the vaccines help protect against rabies?

each stimulates active antibody response in 7-10 days and neutralizing antibodies persist for several years

what are the ways of Human Rabies Biologics?

vaccines and Rabies immune globulin (RIG)

what does the Rabies immune globulin help with immunity?

provides rapid passive immunity for about 21 days

pre-exposure prevention in humans?

• 2 doses of RV on days 0 and 7

• Follow-up: serologic testing to ensure protection 1-3 years later or booster after 3 years w/o titer testing

post-exposure prevention (humans)?

• post-exposure prophylaxis

• post-exposure regimen

what specifically is the post-exposure prophylaxis of rabies?

wound treatment, local infiltration of RIG, vaccination(RV)

what specifically is the post-exposure rabies regimen?

• Not previously vaccinated: thorough wound cleaning with soap and water, RIG (half at bite site/other half IM) - concurrent with first dose of RV, then 4 doses of RV (Days 0,3,7, and 14)

• previously vaccinated: thorough wound cleaning and RV on days 0 and 3 (2 doses)

post exposure prophylaxis is considered a medical urgency not a ?

an emergency

management of exposures in humans?

• approx. 16K-39K people receive post-exposure prophylaxis each year in the US

• pre-exposure prophylaxis alone my not be sufficient to protect w/o post-exposure prophylaxis

• Costs of post-exposure rabies prophylaxis can be significant

what are the recommendations from NASPHV for rabies in domestic animals?

• all dogs, cats, and ferrets be vaccinated

• remove strays and unwanted animals (impound for 3 days in case of ownership or potential exposure)

what are the recommendations for rabies prevention in wildlife?

• NO licensed parenteral rabies vaccines for use in wild animals or wild hybrids

• states are encouraged to enact laws to prohibit importation, distribution, translocation, and private ownership of Racoons, skunks, coyotes, foxes, bats, and other wild species

What is important about rabies vaccines for animals?

• All USDA-licensed vaccines are listed in NASPHV Compendium

• No value in more frequent vaccination than labeled

• Adverse events… are rare in animals (reactions should be reported to USDA/APHIS/CVB)

• No licensed vaccines exist for wild or hybrid animals

• human contact with animal rabies vaccines (injectable nothing happens, oral should be reported)

Pre-exposure prevention guidelines?

• dogs, cats, ferrets, horses, and livestock w/frequent human contact

• wild animals or hybrids should be kept as pets

• vaccination by licensed DVM with approved vaccine

• regardless of age at initial vaccination, animal should be boostered in one year

what is the typical vaccination schedule for dogs, cats, ferrets for rabies?

• initial vaccination at 3-4 months of age

• booster one year later (regardless of initial vaccine type)

• booster every three years

rabies control and prevention in wildlife - carnivores?

• oral rabies vaccines for mass vaccination is considered in select situations (border between Ohio and Pennsylvania, certain regions in Texas, Only by approval with gov’t health agencies)

rabies control and prevention in wildlife - Bats?

• rabid animals reported from all 48 contiguous States

• caused at least 43 human deaths in USA

• Reducing bat populations is neither feasible nor desirable

Management of animals exposed to a rabid Animal - Wild

• any wild mammal carnivores and bats unavailable for testing should be considered rabid

management of animals exposed to a rabid animal - dogs, cats, ferrets?

• Dogs, cats, and ferrets exposed to a rabid animal

  • unvaccinated animals should be euthanized immediately

  • current vaccines should be revaccinated immediately and observed by owner for 45 days

  • Those overdue for booster (with documentation) also should be boostered immediately and kept under owner control for 45 days

management of animals exposed to a rabid animal - livestock?

• unvaccinated livestock should be euthanized immediately

• current vaccines should be revaccinated and observed for 45 days

• multiple exposures in a herd are uncommon

• exposed animal can be immediately custom-slaughtered

• cooking and pasteurization inactivate rabies virus

management of animals that bite humans - dogs, cats, ferrets?

• confined and observed for 10 days

• strays or unwanted animals should be euthanized and tested immediately

how is testing for rabies in animals done?

• accomplished for those animals potentially exposing humans or domestic animals

• for all animals except bats, submit only the head or brain to diagnostic lab

• No USDA-licensed rapid test kits for commercially available antemortem diagnosis

what is the international and interstate Movement?

• CDC regulates the importation of dogs and cats into the US

• Prior to interstate movement for dogs, cats, ferrets, horses:

  • should be current on rabies vaccination

  • accompanied by current, valid rabies vaccination certificate