Wildlife Medicine Flashcards
parasitic zoonoses wildlife diseases wildlife zoonoses
Which of the following are zoonotic?
a. ancylostoma caninum
b. toxocara canis
c. dirofilaria immitis
d. parelaphostrongylus tenuis
a. ancylostoma caninum
b. toxocara canis
c. dirofilaria immitis
Which of the following have the ability to affect wildlife?
a. echinococcus multilocularis
b. toxoplasma gondii
c. babesia canis
d. trichinella nativa
a. echinococcus multilocularis
b. toxoplasma gondii
d. trichinella nativa
What is the definitive host for angiostrongylus cantonensis?
a. cat
b. rat
c. fox
d. pig
b. rat
What is the definitive host for baylisascaris procyonis?
a. fox
b. squirrel
c. raccoon
d. skunk
c. raccoon
How do humans acquire toxoplasma gondii infections?
Through exposure to oocysts (contaminated soil, contaminated tap water, rivers and oceans with runoff containing oocysts, handling wildlife or zoo animals)
or
Through exposure to tissue cysts (white-tailed deer, black bears, necropsy, handling aborted fetuses or placental membranes)
T/F: cats of the definitive host for toxoplasma gondii, but any warmblooded wildlife species can carry tissue cysts and infect humans
true
How do humans get infected with the zoonotic coccidian species, cryptosporidium parvum?
ingestion of oocysts (because they are infective when passed in feces)
oocysts can be in soil, water, and filter-feeding shellfish.
What protozoan parasite causes “beaver fever” and has many assemblages.
giardia duodenalis
How do we test for giardia duodenalis?
SNAP test – detects antigen
describe the appearance of echinococcus multilocularis
tapeworm with 3 segments
very small adults (only 3-6 mm)
T/F: one echinococcus multilocularis egg can produce MANY adults
true
How do humans obtain echinococcus multilocularis infections and what disease does it produce?
egg ingestion from environment
produces human alveolar echinococcus, which can take 10-15 years between exposure and development of clinical symptoms.
what is the definitive host for echinococcus multilocularis?
canids
Why is diagnosis of echinococcus multilocularis difficult in dogs? What is the BEST way to diagnose?
the segments are very small and are rarely seen
flotation might be negative because the eggs are heavy
eggs are indistinguishable from other taeniid eggs
best way to diagnose = PCR
how can you disinfect against echinococcus multilocularis?
- freezing (-80 C) for days
- undiluted bleach for hours
- flame
T/F: echinococcus multilocularis is only found in Canada, Alaska, and Central + Eastern Europe.
false – yes in those areas, but it was also detected in northern midwestern states and eastern US (VA, MD, PA, VT)
What preventative is successful in treating/preventing echinococcus multilocularis?
praziquantel
T/F: if a dog presents to your clinic with an abdominal mass, echinococcus multilocularis should be on your differential list.
true
what human diseases does baylisacaris procyonis cause?
visceral and ocular larva migrans
How do humans get baylisascaris procyonis infections?
raccoons defecate in communal “latrines” which have TONS of eggs.
rodents walk through these latrines and get tons of eggs all over their feet.
rodents then transfer these eggs into the human environment and humans ingest the eggs.
Unlike toxocara, baylisascars larvae do what in the human body?
continue to grow!
they cause lots of tissue damage and severe acute eosinophilic meningoencephalitis
T/F: humans infected with baylisascaris procyonis are never subclinical, the infections are always severe.
false – some are subclinical
how can you control baylisascaris procyonis?
- treat captive raccoons (pyrantel, ivermectin/moxidectin, albendazole/fenbendazole)
- remove racooon feces
- disinfect (flaming the area kills eggs)
An IDEXX antigen test can help you determine coprophagy (just passing eggs) from actual adult worm antigen (parasites within the small intestine) in dogs who can carry eggs in their feces and infection is uncommon.
What are the results for each situation?
coprophagy - negative antigen test
adult worms in SI – positive antigen test
which eggs are larger - toxocara or baylisascaris?
toxocara
_________ is a nematode of the small intestine of warmblooded animals. The larvae produced become encysted in the muscle and are transmitted by carnivory or scavenging or ingestion of undercooked meat.
trichenella
This parasite is transmitted by a snail. It gets within the pulmonary arteries and right ventricles of rodents (mostly rats).
angiostrongylus cantonensis
how can humans get infected with angiostrongylus cantonensis that causes severe eosinophilic meningoecephalitis?
ingestion of snail or larvae (L3)
Where is angiostrongylus cantonensis found geographically?
asia, caribbean, hawaii, and southeastern US (FL)
What is the primary reservoir for hantavirus (a bunyavirus found in western USA)?
rodents (deer mouse, cotton rat, and white-footed mouse)
how is hantavirus transmitted to humans?
virus particles become aerosolized from rodent urine, feces, or saliva and are inhaled
or
through handling rodents
T/F: there are generally no clinical signs associated with hantavirus in mice or rats, but humans experience fever, nausea, vomiting, and cough that progressed to acute respiratory disease, DIC, and even death.
true
how do we control hantavirus spreading?
rodent control
sanitation
protective equipment (gloves, air-purifiers, disinfection, proper carcass disposal)
What is the etiology of the disease Tularemia?
francisella tularensis
What is unique about the hosts for tularemia?
there are 2 different cycles
1. terrestrial cycle – rabbits and rodents
2. aquatic cycle – muskrats and beavers
how is tularemia transmitted?
blood-sucking arthropods
ingestion
inhalation
direct contact
contamination of wounds
What area of the US is tularemia most prevalent in?
central US
There are many types of clinical signs seen in humans with tularemia and animals get white lesion in liver, spleen, and pneumonia.
To reduce the risk of infection, how can we control tularemia?
sanitary precautions
wear gloves
control insect vectors
What is the etiology for plague?
Yersinia pestis (a gram negative bacteria)
What/Who is the host for plague?
this pathogen is maintained in nature through a flea-rodent cycle
reservoir hosts = voles, grasshopper mice, rock squirrels
epizootic rodent hosts = prairie dogs, ground squirrels
non-rodent hosts = felids, black-footed ferret
What is the mode of transmission of plague?
flea bite
the bacteria multiplies within the fleas GI tract, blocks it, and leads to regurgitation of the infected blood into the host.
where in the US are cases of plague more prevalent?
southwestern US (4 corners area)
T/F: Plague has a 50% fatality rate in untreated cases
true
What is biggest sign that plague is occurring within a certain population or area?
rapid decline of colonial rodents
how can you make a definitive diagnosis of plague?
immunohistochemistry (LN, blood, spleen, liver, lung)
how can we effectively manage plague infections?
- treatment of the environment to kill fleas
- local control of rodents close to human habitation
- treat pets for fleas (esp. cats)
What mycobacterium is a problem in northern deer populations?
mycobacterium bovis
how is M. bovis transmitted?
aerosols
consumption of contaminated feed
close contact with infected individuals or contaminated areas
crowding + stress
What are the possible sources of maintenance and spread of M. bovis into deer populations?
high deer population density and supplemental feeding
T/F: M. bovis is only found in cattle
false – it spilled over into deer, elk, and non-cervids (cats, dogs, coyotes, bears, raccoons, etc.)
You do a necropsy on a dead deer that came from near a dairy farm in michigan. You find many yellow pea-sized nodules all within the chest cavity. There are also swollen lymph nodes. What is most likely your presumptive diagnosis?
tuberculosis – M. bovis
how can you test living animals for tuberculosis?
caudal fold tuberculin test
if its positive, call the state vet and have them do a comparative cervical test.
how can we manage tuberculosis?
-reduce deer density
-do not supplemental feed or bait deer
Why are we concerned with reducing tuberculosis infections? (2 reasons)
- loss of bovine TB free status and trade
- public health concern
what agent causes tuberculosis in birds?
mycobacterium avium (a gram positive acid-fast bacteria)
how can we diagnose avian tuberculosis?
culture, PCR, histopathology
post-mortem testing is better
What arthropod virus (transmitted by mosquitoes) causes encephalitis in wildlife?
west nile virus
We know that the west nile virus is passed between birds and mosquitoes. Who are the dead end hosts of west nile virus?
horses
people
What was the source of rapid dissemination of west nile virus from eastern US to the west coast?
bird migratory patterns
how do you diagnose west nile virus?
serology or PCR
how can we work towards preventing west nile virus?
- insect repellent
- environmental larvicides and adulticides
- vaccinate animals (ex. horses)
is WNV zoonotic?
yes
What are the 4 reasons wildlife diseases are important?
- threat to native wildlife populations
- impact on domestic animals
- zoonotic potential
- economic importance
What type of virus is rabies?
single-stranded RNA virus in family Rhabdoviridae, genus lyssavirus
who can become infected with rabies?
all mammals are susceptible
the wildlife reservoirs are carnivores and omnivores
what animal is responsible for the highest # of cases of rabies in VA?
a. raccoons
b. skunks
c. foxes
d. bats
e. rodents
f. domestic animals
a. raccoons
what is the difference between dumb rabies and furious rabies?
dumb – aimless wandering, incoordination, loss of awareness, paralysis
furious – attacks and self mutilation
both end in convulsions, coma, and death
how is rabies transmitted?
direct contact with saliva or nervous tissue of infected animal
aerosol transmission
organ transplant
then it travels from site of entry to the CNS within axons of peripheral nerves
how do you diagnose rabies?
post mortem examination of brain tissue
Fluorescent antibody test (FAT)
histopathology shoes encephalitis and negri bodies
is rabies reportable?
yes
how can we control rabies?
- rabies vaccine for domestic animals (buffer)
- oral rabies vaccine bait for free-ranging carnivores (prevent westward spread)