ANS 42 Lecture Notes - Lecture 17: Zoonosis, Enzootic, Immunocompetence
13 Jan 2017
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Zoonotics
1. Zoonoses: diseases transmitted from animals to humans and the diseases pose a threat to
human health.
a. animal health influences human health and vice versa
b. 30 identified dog and cat diseases
2. Transmitted by:
a. Contact: contacts animal/skin, ereet, respirator seretios, aial’s eviroet,
bites, scratches,
b. Vector: mosquitos, ticks, fleas,
c. Trasplats: hua’s orgas trasplated ito aother perso’s od
i. Eaple: haster had eigitis that affeted door’s lugs
3. Zoonoses can be classified by agent of transmission
a. Viral: submicroscopic element that will reproduce and replicate in a host cell
b. Bacterial: bacteria that are transmitted and will replicate and develop in a host or a
human
i. Tend to have a capacity to live for a long time outside of the host
c. Fungal: fungi, spores
d. Parasitic: caused by free-living organisms that will act as a parasite in order to increase
their size.
i. Example: mites, protozoa
4. Have the greatest impact on the young and the very old humans
a. Reduced immune functions
b. Also for immunocompromised individuals
i. HIV, AIDS
ii. Opposite of immunocompetent
5. Viral
a. Rabies: present in every continent except for Antarctica and maybe Australia
i. Considered enzootic if a reservoir of the zoonotic agent exists in the wild Animal
population
ii. Can be in any mammal
1. Likely due to body temperature
2. Most present in carnivores
3. Transmitted through an open wound
4. Travel from site of infection up through the nerve cells to the spinal
cord. Then up to the spinal cord to the brain.
5. Once in the brain, it multiplies and then causes brain damage
a. Displacing brain tissue for viral tissue
6. Will also travel to the salivary glands
a. Excessive salivation
7. Depends on where the bite happens
a. The deeper the wound and the nearer the brain, the faster the
symptoms
b. Can take as long as 6 months to transmit up to the brain
iii. Three particular phases for symptoms
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1. Prodromal stage
a. Changes in temperament, anxiety, nervousness, behavioral
changes
2. Excitatory stage
a. Extreme agitation and aggressive behavior
b. Sometimes referred to as furious rabies
c. When animal is in the stage where it is transmitting the virus to
the next host
3. Paralytic
a. Short period
b. Limbs and organs are paralyzed
c. Followed quickly by death
d. Called dumb rabies
iv. Once symptoms are shown, it is 99% sure that the person will die
v. Cannot be infectious before showing the symptoms
vi. Prevention: vaccination
1. Need to be given by a veterinarian to ensure that the animal was
vaccinated
vii. Can also be transmitted by airborne aerosols
1. Concerned with bats
2. Since they groom themselves, their saliva can drop to the ground and it
may be transmitted airborne if the dirt is stirred up
b. Newcastle
i. Affects birds (primarily in domesticate fowl but may be in the wild)
1. More in chickens
ii. Respiratory infections and symptoms
iii. Mortality rate: 90% in a group of birds
1. Economically devastating in the fowl industry
iv. Shows up as conjunctivitis in humans
1. Inflammation of the eye
v. Birds can be vaccinated against the disease
vi. Introduced into north America through the pet trade
1. It is an aerosol
2. When the bird sneezes, there is respiratory secretion in the air and that
is how it is transmitted
c. WEE: Western Equine Encephalomyelitis
i. Has a variety amount of hosts
1. Only species that shows the symptoms are humans and horses
ii. Isolated from reptiles
1. only viral zoonotic agent
iii. in horses that show the symptoms, brain inflammation
1. fever, infection in the brain, neurological damage, unsteady gait, lack of
coordination, agitation
2. mortality rate around 40-50%
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