Zoonotic diseases: Bite related zoonoses

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Zoonotic diseasesBite related zoonoses

• Stephen Waring, DVM, PhD
• Assistant Professor of Epidemiology
• swaring_at_sph.uth.tmc.edu
• 731-500-9241

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Bite/Scratch Transmitted Zoonoses

• Rabies
• Animal bites and severe attacks
• Cat Scratch Disease (Bartonella henselae)
• Capnocytophaga canimorsus
• Pasteurella multocida
• Francisella tularensis
• Cercopithecine herpesvirus-1

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Bite/Scratch Transmitted Zoonoses

• A kind and gentle heart he had,  To comfort
  friends and foesThe naked every day he
  clad  When he put on his clothes.
• And in that town a dog was found,  As many dogs
  there be,Both mongrel, puppy, whelp, and
  hound,  And curs of low degree
• The dog, to gain his private ends,  Went mad,
  and bit the man.
• The man recovered of the bite,  The dog it was
  that died.

An Elegy on the Death of a Mad dog by Oliver
Goldsmith
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Bite/scratch transmission Rabies

• Viral infection
• Worldwide
• Concentrates in saliva
• Transmitted by bite or scratch from a rabid
  animal
• Invariably fatal with very few exceptions
• Primarily a disease of animals

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Rabies

• Host cycle
• Skunk-to-skunk
• central US west Texas
• Raccoon-to-raccoon
• eastern US
• Red fox-to-red fox
• Canada
• Fox-to-fox (grey) coyote-to-coyote
• Texas

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Rabies

• Host cycle
• Bat rabies
• tends to cycle in migratory and some sedentary
  insect eating colony bats
• Most human cases of bat rabies are from migratory
  solitary bats

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Rabies

• Temporal cycle
• Seasonal
• most terrestrial wildlife species peak in the
  Spring may have second peak in the Fall
• bats peak in late summer
• domestic animal peaks follow terrestrial wildlife
  peaks by 3 to 5 weeks
• bats dont influence domestic animal peaks

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Rabies

• Temporal cycle
• Secular trends
• foxes often have 3 to 5 year cycles
• skunks often have 5 to 8 year cycles
• not much data on other wildlife hosts

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Rabies

• Clinical features
• Incubation period 3-8 weeks (9 days to 7 years)
• Signs not definitive, but all animals exhibit
  typical CNS signs
• Behavioral changes
• Anorexia, nervousness, hyperexcitability
• CNS ataxia, altered phonation, aggressiveness
  loss of fear in wild animals nocturnal animals
  wander in daytime

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Rabies

• Clinical features
• Stages
• Prodromal (1-3 days) vague signs
• Excitative rapid intensification furious
  rabies form (mad dog) refers to animals with
  pronounced excitative phase
• Paralytic rapid onset of paralysis, followed by
  death within 10 days dumb rabies form refers
  to animals with predominant paralytic features
  and minimal behavioral changes

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Rabies

• Prevention
• Domestic animals
• routine vaccination programs (annual for dogs
  cats in TX)
• Terrestrial wildlife
• baited oral rabies vaccine programs for both grey
  and red foxes also raccoons, and coyotes

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Rabies

• Animal vaccine
• Regulated by USDA, APHIS, Veterinary Biologics
  Division
• Vaccinated Animals
• 1) Number 25
• 2) Protection from challenge 86
• Unvaccinated Controls
• 1) Number 10
• 2) Succumb to rabies 80

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Rabies

• Animal vaccine
• Oral Rabies Vaccines
• Approved for Federal and State Agencies use only
• Approved for Raccoons, Coyotes and Foxes

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Rabies

• Prevention - humans
• Pre-exposure prophylaxis
• for high risk occupations and travelers to high
  risk countries.
• Post-exposure prophylaxis
• treatment regimens following exposure to
  potentially rabid or confirmed rabid animal

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Rabies

• Human vaccine
• IMOVAX
• human diploid cell vaccine (HDCV)
• IM or ID (pre-exp only)
• RVA (Rabies Vaccine Adsorbed)
• Rhesus monkey fetal lung cell vaccine
• IM
• RABAVERT
• Purified chick embryo cell vaccine (PCECV)
• IM

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RabiesBat proofing your house
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Bite Transmitted ZoonosesSevere Animal Bites

• Background
• domestication of dogs for hunting, protection,
  companionship began over 12,000 years ago
  (Nature, 1978)
• still retains some of natural instincts,
  including attack-related behaviors (provocation,
  fear, protection of food and young,
  territorialism)
• bites have a major impact on health care
  utilization and costs

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Bite Transmitted ZoonosesSevere Animal Bites

• Background
• estimated 33 of US households own a dog
• 50 million dogs and 60 million cats in US
• one of every two people will be bitten by a dog
  or another person during their lifetime
• more than 70 of victims are bitten by their own
  pet (breaking up a fight) or by an animal known
  to them
• 80 of animal-bite wounds are from dogs

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Bite Transmitted ZoonosesSevere Animal Bites

• Definitions
• severe attack - one in which the animal
  repeatedly bites or attacks (shakes) the victim
  and extreme difficulty encountered in terminating
  attack
• severe bite - a puncture or laceration which
  breaks skin, resulting in a sufficient degree of
  trauma to seek medical treatment independent of
  rabies prevention
• an attack can be by any animal, but the
  overwhelming majority are by dogs

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Bite Transmitted ZoonosesSevere Animal Bites

• Epidemiology
• Incidence
• estimated to be 0.5-4.5 million per year in US
  based on surveillance and monitoring
• 0.3 - 1.1 incidence of emergency department
  treated bites
• based on CDC Injury Control and Risk Survey,
  estimated 800,000 required medical attention
• Mortality
• 15 fatalities per year (1979 - 1988)

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Bite Transmitted ZoonosesSevere Animal Bites

• Epidemiology of dog bites (JAMA, 1998)
• National Hospital Ambulatory Medical Care Survey
  (NHAMCS)
• survey conducted under direction of CDC/National
  Center for Health Statistics
• ICD-9 E code of E906.0 (dog bite)
• only included those coded as injury, first
  visit
• Injury Severity Score imputed from primary and
  secondary diagnoses
• used data from 1992-1994

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Bite Transmitted ZoonosesSevere Animal Bites

• Epidemiology
• Results
• Injuries comprised
• Annual incidence of 12.9 per 100,000 (95 C.I.,
  10.5 - 15.4)
• Rates were higher in rate being 60.7 per 100,000 in 5-9 year old males
  (3.6 of all injury-related ED visits for this
  group)
• face, neck, and head (combined) was the most
  common region affected (29)
• 58 of all bite injuries occurred at home
• 96 were treated and released (99 were of lowest
  assigned severity score)

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Bite Transmitted ZoonosesSevere Animal Bites

• Epidemiology
• Conclusions
• based on an average payment of 274 per patient,
  annual cost represents 102 million
• based on estimates of dog population and
  dog-owning households, potential risk may be much
  greater
• evaluation of prevention strategies and their
  effectiveness is imperative
• information regarding high-risk situations is
  needed
• improved bite-reporting systems need to be
  developed and implemented

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Bite Transmitted ZoonosesSevere Animal Bites

• Surveillance - Texas
• voluntary reporting to TDH-Zoonosis Control
  Division
• 1997 729 severe animal attacks
• dogs accounted for 620 (85)
• 30 Chows, Rottweilers, Pit Bulls, German
  Shepherd
• 21 Mixed, cross with above, Labrador cross
• 49 All other breeds
• cats accounted for an additional 86 (12)

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Bite Transmitted ZoonosesSevere Animal Bites

• Surveillance - Texas
• Animal characteristics associated with attacks
• canine sex (550 reports)
• Female 75 (77/103) were intact
• Male 86 (223/260) were intact
• behavior prior to attack (570 reports)
• 64 were described as docile or friendly
• 36 displayed warning
• 9 were multiple animal involvement
• 51 were not currently vaccinated (491 reports)

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Bite Transmitted ZoonosesSevere Animal Bites

• Surveillance - Texas
• Victim characteristics associated with attacks
• Extent of injury (266 reports)
• 78 required sutures
• 47 were sufficient to required surgery and/or
  hospitalization
• Age
• 44 were
• Children under 11 years of age were 4 times more
  likely to be a victim
• Location of injury
• most were multiple site wounds
• 42 involved head, neck, or torso (indication of
  severity)

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Bite Transmitted ZoonosesSevere Animal Bites

• Education
• Collective effort by humane organizations, animal
  control agencies, schools, family care
  practitioners, veterinarians, and parents
• Basic animal behavior
• Informed pet owners
• Avoid potential problem breeds for family pet
• Surgical sterilization for all pets not to be
  used for breeding

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Bite/scratch transmission

• Cat scratch
• Bacterial infection
• Bartonella spp.
• Worldwide
• Human infection primarily associated with
  exposure to domestic cats

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Bite/scratch transmission

• Cat scratch
• Cats are asymptomatic carriers, serving as both
  vector and reservoir host
• May have chronic bacteremia
• Greatest risk associated with traumatic cat
  contact with kittens and young cats
• Fleas may play role in facilitating reservoir
  maintenance (cat-cat transmission) uncertain
  role as vectors for human transmission

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Bite/scratch transmission

• Control measures
• Quarantine
• Observation
• Treatment
• Proper handling techniques
• Protective clothing
• Prophylaxis

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Zoonotic DiseasesMore information