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Zoonotic diseases: Bite related zoonoses

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Title: Zoonotic diseases: Bite related zoonoses


1
Zoonotic diseasesBite related zoonoses
  • Stephen Waring, DVM, PhD
  • Assistant Professor of Epidemiology
  • swaring_at_sph.uth.tmc.edu
  • 731-500-9241

2
Bite/Scratch Transmitted Zoonoses
  • Rabies
  • Animal bites and severe attacks
  • Cat Scratch Disease (Bartonella henselae)
  • Capnocytophaga canimorsus
  • Pasteurella multocida
  • Francisella tularensis
  • Cercopithecine herpesvirus-1

3
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
4
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

5
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

6
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

7
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

8
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

9
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

10
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

11
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

12
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

13
Rabies
  • Animal vaccine
  • Oral Rabies Vaccines
  • Approved for Federal and State Agencies use only
  • Approved for Raccoons, Coyotes and Foxes

14
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

15
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

16
RabiesBat proofing your house
17
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

18
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

19
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

20
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)

21
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

22
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)

23
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

24
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)

25
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)

26
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)

27
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

28
Bite/scratch transmission
  • Cat scratch
  • Bacterial infection
  • Bartonella spp.
  • Worldwide
  • Human infection primarily associated with
    exposure to domestic cats

29
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

30
Bite/scratch transmission
  • Control measures
  • Quarantine
  • Observation
  • Treatment
  • Proper handling techniques
  • Protective clothing
  • Prophylaxis

31
Zoonotic DiseasesMore information
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