Animal Hazard Occupational and Safety Program

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Animal Hazard Occupational and Safety Program

• VSC 443/543 Research Animal MethodsSusan E.
  Wilson-Sanders, DVM., M.S.

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Occupational accidents account for more than 120
million injuries and at least 220,000 deaths a
year
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The purpose of an occupational health and safety
program is to minimize risks of occupational
injury and illness by controlling or eliminating
hazards in the workplace.
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Risks

• A measure of the likelihood of a consequence.
• It is a statement of the probability that harm,
  injury, or disease will occur.

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Risk

• Frequency of animal contact
• Intensity of exposure
• Hazards associated with the animal
• Hazardous properties of agents used in research
• Susceptibility of individuals
• Hazard control measures available
• Occupational history of the individual

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Hazards

• Hazard is an inherent danger in a system or
  material
  
• Hazards could be obvious
• Lifting a heavy animal
• Putting fingers into a cage
• Hazards could be hard to see
• Aerosolized diseases
• TB

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Hazards

• Are recognized risks
• May be attenuated through modifying the
  underlying factors that contribute to the risk.
  
• Such as behavior change.

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Risk Assessment - Implementation

• Questionnaire
• Anticipated animal exposure
• Medical history
• Home life
• Children, pets
• Pre-employment health exam
• Pregnancy risks
• Lifting
• Immunodeficient conditions

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Zoonotic diseases - hosts all animals
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Common Zoonoses

• Toxoplasmosis
• Rabies
• Herpes B
• Salmonella
• Tb
• Giardia
• Shigella
• Q fever
• Hepatitis A, B

• Pox virus
• Leptospiros
• Cryptosporidia
• Chlamydia psittaci
• Erysipelothrix
• Cat Scratch
• Toxacara
• Tularemia
• Infection - bites

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Toxoplasmosis

• Toxoplasma gondii
• Occurs in almost all warm-blooded animals and
  many birds
  
• Humans become infected by
• Eating infected meat
• Congenital transmission
• Drinking contaminated water, milk, food
• Approx. 30 - 40 humans in US have antibodies

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Toxoplasmosis - Forms

• 3 Oocysts (sporozoites)
• Occur only in feline family - cat is definitive
  host

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Toxoplasmosis and Cats

• Cats become infected by eating intermediate hosts
  with tissue cysts.
  
• Prevalence of oocysts in cat feces is low.
• Rarely found in fecal exam of cats.
• Cats can become ill, not usually when shedding
  oocyst.

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Human Disease

• Congenital
• Transplacental transmission in 55 untreated
  and 22 treated pregnant women
  
• abortion, stillbirth, signs, no signs.
• hydrocephalus
• signs many not be noted at birth but occur later
  in life.

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Human Disease

• Congenital
• Incidence of fetal infection depends on trimester
  infected.
  
• 2nd and 3rd (untreated) 54 - 65 fetal
  trans., more asymptomatic
  
• 1/1,000 - 1/10,000 births infected
• 5.3 bill in 1993
• Approximately 30 women of childbearing-age have
  antibodies.

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Toxoplasmosis - Prevention

• Reduce oocysts in environment.
• No correlation with cat ownership.
• Reduce feline infections and oocyst shedding.
• Cat owners/handlers - use proper hygiene.

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Toxoplasmosis - Prevention

• Cover childrens sandboxes.
• Proper disposal of cat feces.
• Wash hands.
• Cook meat well.
• Wash fruits and vegetables.
• Pregnant women should be especially careful.
• Use gloves when gardening.

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Cercopithecine Herpesvirus 1

• Transmission
• Diagnosis
• Treatment
• Prevention

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Cercopithecine Herpesvirus 1

• Herpes B, B virus
• 1st reported in lab workers - 1932
• Enzootic in Asian old world monkeys of genus
  Macaca
  
• Fatal in some New World primates
• Not described in African old world monkeys

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Cercopithecine Herpesvirus 1

• Natural infection in monkeys similar to HSV in
  humans.
  
• Mild or no overt signs latency.
• Shed virus during shipping/stress.

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Cercopithecine Herpesvirus 1

• Rare human infection.
• Incubation approx. 3 days 3 weeks (10
  yrs.?)
  
• Death in approx. 70 cases 1-3 weeks after onset
  of symptoms.

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Disease of Antiquity
RABIES
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Viral Characteristics

• Family Rhabdoviridae
• Genus Lyssavirus
• Rabies
• can infect all warm blooded animals.
• species specific strains (skunk, raccoon, bat,
  canine, fox).

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Facts, Figures, and Epidemiology of Rabies
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Worldwide

• Known to exist in Egypt before 2300 B.C.
• Occurs throughout the world.
• 35,000 - 100,000 deaths a year worldwide.
• Majority from dog bites.

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Worldwide

• Dogs account for 52 of animal cases
• Wildlife (raccoons, skunks, foxes, jackals,
  wolves, others) 41
  
• Bats 6

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United States

• 1700s dog and fox cases in Mid-Atlantic states
  
  
• 1938 became reportable disease
• 1960s transition from domestic to wild animals
• 1995 7,247 rabid animals

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Rabies in Animals

• Pathogenesis and Signs

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Rabies in Animals

• Incubation usually 2 - 8 weeks
• Prodromal, furious (excitatory)
• First signs of rabies in animal is behavior change

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PathogenesisAnimals (and Humans)

• Rabies retrograde intra-axonal 100 - 400 mm/day
• Reaches CNS - salivary glands
• Incubation depends on site of inoculation
• Death may occur prior to salivary involvement
• Viral excretion prior to neurological signs
  possible

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Signs of Rabies in Animals

• Prodromal
• Dog 2-3 days nervous, anxiety, solitude, fever,
  shy or snap, lick/chew bite site
  
• Cat same as dog but erratic and unusual behavior
  for 1-2 days. Often develop paralytic directly
  from prodromal.

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Signs of Rabies in Animals

• Furious
• Dog 1-7 days irritable, hypersensitive to sound
  and stimuli, excitable.
  
• Cat more consistently develop this phase.
  Erratic biting/scratching.
  
• Cow hypersensitive to sound/movement, may
  attack animals or objects, hoarse loud bellowing,
  sexual excitement, finally collapse into
  paralytic phase then death.

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Signs of Rabies in Animals (cont.)

• Cat develops 5 day of signs similar to dog
  with little drop jaw. Incoordination,
  paralysis.
  
• Cow knuckling of hind fetlocks, swaying on walk,
  decreased sensation, tenesmus, drooling, yawning
  (voiceless bellowing).

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Signs of Rabies in Animals (cont.)

• Paralytic
• Dog develops 2-4 days after 1st signs. LMN
  paralysis of limb, laryngeal paralysis bark
  changes in tone, salivation, inability to
  swallow, dropped jaw.

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Diagnosis

• History, signs
• Postmortem
• Direct immunofluorescent-antibody test (DIFA)
• Negri bodies
• Mouse inoculation

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Differential Diagnosis

• Rabies should be considered in cases of rapidly
  progressing encephalitis, even when there is no
  known exposure.

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Human Cases - United States

• Since 1980,
• 34 human cases

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Arizona

• Arizona 4 human cases since 1943
• Last in 1981

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Routes of Rabies Transmission

• Bites, scratches, mucous membrane contact.
• Tissue exposure.
• Aerosol transmission possible, rare.
• Corneal transplant.

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Human Disease

• Signs and Diagnosis

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Signs of Rabies in Humans

• Incubation period 1 - 3 months
• Three phases
• Prodromal
• Excitatory
• Paralytic

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Prodromal Phase

• Fever, malaise, headache, nausea, anorexia, sore
  throat, anxiety, melancholia
  
• Hyperesthesia increased sensitivity to light,
  noise, and movement
  
• Dilated pupils
• Abnormal sensation at wound site

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Paralytic Phase

• Symptoms of paralysis predominate in 20 of
  cases
  
• May precede death by 1-4 weeks
• Hydrophobia disappears
• Progressive, general flaccid paralysis
• Progress to stupor then coma
• Vascular collapse and death

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Excitatory Phase

• Seen in - 80 of cases.
• Increased anxiety, apprehension, impending doom
  sensation.
  
• Hydrophobia.
• Respiratory arrest or coma.

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Diagnosis

• Antemortem
• Saliva or throat swabs, CSF, urine, nasal or
  conjunctival secretions
  
• FRA demonstration of viral antigen in neural
  structures of facial or posterior nuchal skin and
  corneal cells (press slide to cornea)

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Wildlife Rabies

• Raccoons, Bats, and Coyotes

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Raccoons

• 1990 most reported rabid animal in USA.
• Mid-Atlantic epizootic.
• Constant move north into New England.
• Mid-Atlantic and New England account for 89 of
  all rabid raccoons in USA.

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Raccoons

• New York went from a few hundred fox cases to
  over 2000 raccoon cases
  
• No documented human cases from raccoons
• Why not?
• Recognized bite and PEP sought.
• Vaccinated pets as barrier.

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Bats

• Every bat is considered rabid!
• No geographic boundaries.
• Paralysis 1st sign, not behavior change.
• Can transmit rabies to terrestrial animals.
• Only 3 human deaths in Europe attributed to bats
  in last 30 years.

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Bats

• Rabies is in most US bat species
• Insectivorous bats - United States
• Activities that increase exposure to bats should
  be curtailed or reevaluated
  
• Outdoor cats will play with drowned bats

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Prevention of Rabies

• The Key to Controlling the Disease

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Human Prevention

• Vaccinate pet dogs and cats
• Follow leash laws
• Teach children (and adults) not to touch sick or
  injured wildlife
  
• Seek appropriate prophylaxis
• Post-exposure prophylaxis

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Human Pre-exposure Immunization

• Two types
• Human diploid cell vaccine (HDCV), ID

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Post-Exposure Prophylaxis (PEP)
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PEP

• Thorough cleansing of all wounds with soap and
  water- Most Important Step
  
• Assess need to begin PEP series
• animal vaccination history, owner compliance for
  quarantine
  
• Immunization status of person bit

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If an Animal Bites

• Immediately wash wound
• Consult physician
• Notify local animal control department
• Determine rabies vaccine status of animal
• Quarantine (except wildlife)
• Test animal for Rabies

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PEP

• Recommended for all persons with bite, scratch,
  or mucous membrane exposure to a bat.
  
• Appropriate even in absence of a demonstrable
  bite or scratch.
  
• Sleeping person awakes to find bat in room.

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PEP

• Once started - do not discontinue because of
  local or mild systemic reactions.
  
• Begin as soon as possible.
• No reported failures of PEP in USA.

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Vaccination of Animals
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Vaccination of Pets

• Purpose to create barrier between human and
  enzootic rabies reservoir.
  
• Biggest problem in prevention is poor vaccination
  of animals - especially dogs.

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Vaccination of Pets

• Dogs 3 months, 1 yr. later, then as required by
  law.
  
• Cats recommended.
• Ferrets not required in all states.
• Livestock consider only if valuable or regular
  contact with humans in rabies epizootic area.

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Vaccination of Wildlife Oral Baits

• Vaccinia-rabies glycoprotein recombinant virus
  vaccine.

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Risks

• Risk for international travelers is greatest in
  areas where canine rabies is still highly
  endemic, including many parts of Africa, Asia and
  Central and South America.

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United States

• Domestic - 8