Exam 1 Flashcards
Paratenic host
- intermediate host required for completion of lifecycle
* no development of parasite occurs
Percutaneous
o Made, done, or effected through the skin
Sporotrichiosis Basics & effects on humans vs cats
o Sporothrix schenkii o Dimorphic fungus o Soil saprophyte o Can be gotten from rose garden pokes o Reverts to yeast in tissue (37 degrees C)
Humans
• Nodular, ulcerative pyogranulomatous dermatitis.
• Nodules along lymph channels near surface of skin.
• Infrequently can affect lungs, joints, CNS
Cats
• Nodular, ulcerative pyogranulomatous dermatitis
• Adult cats are usually resistant
Sporotrichiosis Diagnosis, Treatment, Client Education
Diagnosis
• Cytology on exudates from lesion
• Looking for polymorphonuclear things
Treatment
• Itraconazole
Client Education
• potential for transmission from cat lesions.
• Wear gloves; wash hands
Classification of zoonoses based on hosts
Direct zoonoses
• One vertebrate host
• Transmission through contact, aerosol, vehicle, or mechanical vector
Cyclozoonoses
• 2 vertebrate hosts
Metazoonoses
• Biological vector
Saprozoonoses
• Has an environmental stage
Mycobacterium Species
M. tuberculosis:
• Human-to-human (elephants)
M. avium complex:
• disseminated disease in immunocompromised patients.
M. avium paratuberculosis:
• Johne’s disease, Crohn’s Disease?
Other “Atypical mycobacterial diseases”
• M. marinum (fish), M. chelonae (pedicures)
M. leprae:
• leprosy, human-to-human Armadillo-to-human
Reservoir & Hosts for M bovis
Reservoir for M bovis
• Cattle
• Does not multiply outside host
Hosts • Cattle, humans, swine, goats, dogs, rarely cats • White-tail deer, elk, bison • Badgers in the UK • Brush-tailed possums in New Zealand
Transmission of M bovis
Infected bovine to non-infected
• Aerosol or milk
Infected bovine to humans
• Mostly milk worldwide but more aerosol in US
Infected bovine to other animals
• Raw milk or aerosol
Humans to non-infected bovine
• aerosol
Vaccine for M bovis
- BCG vaccine
- Attenuated strain of M bovis
- Used for humans
- Can stimulate immune system in cancer patients
- Can cause infection in AIDS patients
Diagnosis of M bovis
• Histopathology of lesions using acid-fact stain will be (+)
for ALL Mycobacteria
Live animals
• Skin (antigen) testing
Postmortem
• Culture, PCR (NVSL)
Testing for M bovis in different species
- Done by accredited vets or state/fed vets
- Done for interstate or international shipment
Cattle bison goats
• Caudal tail fold test
Camelids
• Axillary skin region
Cervids
• Single cervical test
Performing a caudal fold test
- Inject 0.1 purified protein derivative, tuberculin Ag ->
- Return and read in 72 h +/- 6 h
- Vet who made the injection must be vet who reads test result.
- determine results by observation and palpation of site
US State Accreditation for Dz’s
- USDA-APHIS-VS regulate inter-state (between states) movement of livestock
- States regulate intra-state movement (state’srights)
- used for Bovine TB, Brucellosis, Equine Infectious Anemia
- Uniform rules are developed to control diseases
- Status is given to areas (states) free of disease
- Movement between areas (states) is less restricted when status is “free”
Basics of M avium & M tuberculosis
M avium
• No Federal control program
• environment is Reservoir
M tuberculosis
• Maintained in Humans & NH primates
• Some other animals are susceptible pigs, dogs
What does a (+) caudal fold test mean & what are the regulations?
Positive response
• delayed hypersensitivity ->
• TH1/macrophage response (cell mediated) ->
• Swelling ->
• Means the animal has been exposed
• Responder: (+) response
• Reactor: reacts specifically to M. bovis
Regulations for positive reactions • Reactors sent to slaughter • Post mortem inspection • No lesions -> pass carcass for cooking • Lesions -> condemn carcass
Taenia saginata (Cysticercus bovis) & Taenia solium (Cysticercus cellulosae) life cycle, & hosts
Lifecycle in human • Tissue cyst in animal -> • human eats undercooked meat & ingests cysticerci -> • shed eggs in feces -> • animal picks up eggs
Definitive Hosts
• House adult tapeworms
• T. saginata - Humans
• T. solium- Humans
Intermediate Hosts
• House larvae
• T. saginata – cows
• T. solium – swine
T. saginata & T. solium Dz in humans & control
Disease in humans • Taeniasis • rarely clinical • Human cysticercosis • serious, CNS and ocular
Control • Prevent infection in animals • Prevent access to human feces • Treat human cases • Meat inspection • “Measly beef” • Condemn carcass if severe • If can trim, require freezing or cooking before sale. • Cook meat well done
Rickettsia rickettsii (Rocky Mountain Spotted Fever); basics, hosts, & transmission
o Prefer endothelial cells -> vasculitis & rash
o Comes from Dermacentor & Rhipicephalus ticks
o Transmitted transovarian or transstadial
o Ticks infected for life
Hosts
• Wild rodents, lagomorphs, dogs. Opposums, humans
• Humans & dogs are dead end
Transmission
• Tick bite
Rickettsia rickettsii Dz in humans Vs animals
Dz in humans • Incubation: 2-14 days • Fever, chills, muscle • joint pain (flu-like) • Rash • Vasculitis • Tx greatly shortens clinical course • 15-20% fatal if not Txed • Most frequently reported rickettsial dz in U.S.
Dz in animals
• Inapparent in most wildlife
• Dogs: fever, abdominal pain, depression, lethargy, anorexia, neurological signs
• Thrombocytopenia
Rickettsia rickettsii Diagnosis, Treatment, Control
Diagnosis:
• Serology (paired sample)
• Isolation of organism from blood
• PCR
Reportable disease in humans in the U.S. G.
Treatment:
• Tetracycline, Doxycycline
Control
• Vector control
• Tick removal
Definitive Vs Intermediate Host
Definitive
o organism in which the parasite reaches the adult stage and reproduces sexually.
Intermediate
o organism which harbors the sexually immature parasite.
Management of Dogs, Cats, & Ferrets Exposed to Rabies
Unvaccinated
• Euthanize
OR
• Strict quarantine for 4 mo. (D + C) 6 mo. (F) ->
• vaccinate w/in 4 days or 1 month before release ->
• If unable to do at entry, extend isolation to 6
mo.
Vaccinated
• revaccinate w/in 4 days ->
• keep under owner’s control and observe for 45 days
Vaccinated, but not current
• case-by-case evaluation
Management of Livestock & Horses Exposed to Rabies
Previously vaccinated
• Revaccinate immediately ->
• Observe for 45 days
Unvaccinated
• Euthanize immediately
OR
• Close observation for 6 mo
Euthanized immediately after exposure
• Eat meat
Management of Animals that Bite Humans
Cat, dog, ferret
• 10 day observation
• do not vaccinate
• euthanize & test if develop rabies signs
Other animals
• Usually euthanize and test
Pre & Post Exposure Rabies Prohylaxis Humans; vx options
Pre
• People @ risk
• 3 injections @ days 0, 7, 21e
Post determined by • Biting species • Geographic location • Circumstances • Type of exposure
Rabies Biologics
• human diploid cell vaccine (HDCV), IM or ID (deltoid region)
• Purified Chick Embryo Cell Vaccine (PCEC)
• HRIg - neutralizing antibody
Protocol for Humans Post Exposure to Rabies
If not previously Vxd
• Wound cleaning
• 4 IM vaccinations (0, 3, 7, 14)
• HRIG on day 0 around and into the wounds.
• Any remaining volume injected IM at site distant from vaccine site.
If previously Vxd
• Wound cleaning
• 2 IM vx on day 0 & 3
• No HRIG
If Pregenant
• No indication of fetal harm due to Vx
Brucellosis abortus Basics Reservoir, other hosts, in humans, transmission
Reservoir
• Cattle bison elk
Other hosts
• Humans, horses, dogs
In humans
• Undulant fever or Malta fever and arthritis
• Raw milk or direct contact with infected animals or their fluids.
Brucellosis abortus Vaccine
- RB-51
- Approved for cattle in 1996
- Live Culture
- Rifampin & Penicillin resistant strain of B. abortus
- replaced the Strain 19 vaccine in cattle
- Antibodies to RB-51 can be differentiated from “wild type”
- Can cause abortion in bison
What to do if a human comes into contact with RB-51
- Prompt medical attention
* 3-week course of doxycycline
Disadvantages of Brucella Vx Strain 19 Still Used in Elk
Cattle
o abortion and orchitis
Humans
o Milder disease than field strain
o Accidental (usually self)
inoculation
o Human transmission not naturally transmitted
• Persistent titers
Brucella Suis Basics & Effects on Humans
o Focal granulomatous lesions in bones and joints
o Can cause endometritis, infertility
o USDA Eradication
Program
o No quarantined swine (domestic) herds left in the U.S.
Effect on Humans
• Pathogenic
• Direct contact w/ infected pigs
• Cases in hunters of feral swine
Brucella Suis State/Federal Eradication
- All intact swine >6mo must test (-) for brucellosis or originate from brucellosis-free herds
- All state currently brucellosis free
- Feral swine surveillance program
Brucella melitensis
o Effects goats, sheep, camelids o Not in US o Most pathogenic for humans o B. abortus VX does not protect o No approved VX o Also established in cattle in some European & middle eastern countries
Brucella canis
o Effects dogs
o Only ~30 cases ever reported
o Risk to humans very low
o Causes discospondylitis
Brucella Ovis
o Primarily causes epididymitis in rams
o Not zoonotic
o Shed in high numbers in uterine fluids -> abortion
o Transmitted orally through milk or fluids
Brucella & Food Safety
o Unpasteurized milk main source of human infection worldwide
o Meat not known to be source of infection
o Killed by cooking, acid pH, autolytic changes
Transmission & Entry for Brucella SPecies
Inhalation (respiratory)
• Organism aerosolized when shed in high numbers in uterine fluids and urine.
• Most common route for humans
Conjunctiva
Percutaneous
Venereal
• Important rote for suis & canis
In utero
• Causes abortion
