Arboviruses (Exam 5) Flashcards
Arbovirus means _______-borne.
arhtropod
Arboviruses have a replication cycle in nature involving blood-feeding _______ and ________ host.
arthropod
vertebrate
Which 3 species are typically vertebrate hosts for arboviruses?
birds, primates, rodents
Hosts that are asymptomatic, tolerant, and subclinical to Arboviruses with a low viremia are called:
reservoirs
Hosts that are asymptomatic OR symptomatic with a high viremia are called:
amplifiers
Accidental hosts with a low viremia where the disease cycle ends are called:
“dead-end” hosts
Benefits of arboviruses are that they easily cross species barrier and be transmitted over winter via which two routes?
transovarial or transstadial (tick)
When a virus is amplified in reservoirs or extends beyond usual host range this is called _______ disease.
epidemic
In Epidemic Disease, ________ hosts are NOT supportive of replication.
dead-end
Reservoir hosts are mostly responsible for arbovirus replication and transmission in a ________ or ______ cycle.
enzootic or endemic
Two families discussed that are contain Arboviruses are:
Togaviridae
Flaviviridae
What arbovirus disease is caused by an alphavirus within Togaviridae?
Equine Encephalitis
Alphaviruses which cause Equine Encephalitis are _______-borne, (enveloped/nonenveloped), (ss/ds) (DNA/RNA) viruses.
arthropod
enveloped ssRNA
Alphaviruses primarily use ______ as reservoirs and amplifying hosts. ______ and _______ are “dead-end” hosts.
birds
horses & humans
Equine Encephalitis occurs when a mosquito bites and the alphavirus replicates in _________ cells, goes to regional lymph node, and replicates in _______ causing a primary viremia.
dendritic
lymphocytes
After Equine Encephalitis causes a primary viremia, muscle, connective tissue, and endothelium are infected, leading to:
secondary viremia
Once a secondary viremia occurs in Equine Encephalitis, the virus goes on to infect ________, ______, and endothelium, causing encephalitis.
neurons, glial cells
Which 3 alphaviruses cause type of Equine Encephalitis?
Eastern Equine Encephalitis Virus
Western Equine Encephalitis Virus
Venezuelan Equine Encephalitis
Which virus causing Equine Encephalitis is the most virulent and severe?
Eastern Equine Encephalitis Virus (EEEV)
Fill-in the blanks for Eastern Equine Encephalitis Virus:
Accidental hosts (3): _________
Reservoirs: ________
Accidental: humans, horses, large birds
Reservoirs: marsh birds
(T/F) WEEV is nearly 100% fatal in horses.
False (EEEV)
Western Equine Encephalitis Virus is a natural recombinant of _______ and non-pathogenic _______ virus.
EEEV
aura
(T/F) There are only sporadic cases of WEEV.
True
WEEV has 3 epizootic and 5 enzootic lineages but only ________ are neurovirulent.
epizootic
Fill-in the blank for WEEV:
Accidental hosts (2): _________
Reservoir hosts: ________
horses, humans
wild birds
Which alphavirus causing Equine Encephalitis is a reportable foreign animal disease?
Venezuelan Equine Encephalitis V (VEEV)
Which Equine Encephalitis has the highest zoonotic risk, as horses are amplifying hosts?
Venezuelan Equine Encephalitis (VEEV)
Fill-in the blank for VEEV:
Accidental host (2): ________
Amplifier: ________
humans, dogs (rare)
horses
Horses with VEEV have a (low/high) viremia and are (infectious/non-infectious).
high
infectious
Which Equine Encephalitis virus only uses humans as the “dead-end” host and not horses?
VEEV
Clinical Disease/Syndromes of Equine Encephalitis can occur in two forms:
- inapparent/subclinical
- encephalitis
(T/F) You can distinguish between Equine Encephalitis viruses based on the clinical signs.
False
Depression, anorexia, drooping ears, and swollen eyelids are all signs of Encephalitis in horses together called:
“Sleeping Sickness”
Apart from “Sleeping Sickness” signs, non-specific ________ signs can occur in horses with Encephalitis.
neurologic
(T/F) There are NO gross lesions observable with Equine Encephalitis.
True
Encephalitis in horses presents as a (suppurative/nonsuppurative) __________.
non-suppurative polioencephalomyelitis
Regarding diagnosis of Equine Encephalitis, the virus can only be isolated when its in the blood during _________.
fever
What is the main method for antemortem diagnosis of Equine Encephalitis?
serology
In horses, which types of Equine Encephalitis are considered core vaccines?
EEEV
WEEV
Within the family Flaviviridae, which veterinary relevant virus is also a mosquito-borne arbovirus?
West Nile Virus
West Nile Virus within the family Flaviviridae is witin the genus:
Flavivirus
West Nile Virus, of Genus Flavivirus, is a(n) (enveloped/nonenveloped) (positive/negative) sense (ss/ds) (DNA/RNA) virus.
enveloped positive ssRNA
Flavivirus uses _______ for receptor ligand binding and cell fusion.
E protein
(T/F) West Nile Virus is a reportable disease in Missouri.
False (not anymore)
West Nile Virus is the leading cause of _______ arboviral encephalitis in the US.
human
80% of humans infected with West Nile Virus are asymptomatic. The rest develop ________ form or non-_________ form.
neuroinvasive
List 3 species that can be affected by West Nile Virus.
birds
humans
horses
Fill-in the host information for WNV:
Primary amplifying hosts (2): _________
Environmental sentinels: _________
“Dead-End” hosts (2): _______
house sparrow, robin
corvids (blue jay, crow, magpies)
humans, horses
_______ are possible amplifying hosts for West Nile Virus.
alligators
Regarding WNV, once a mosquito bites, the virus replicates in ________ and _______ cells causing a viremia which disseminates to CNS, causing encephalitis.
fibroblasts
endothelial cells
(T/F) Clinical signs for WNV are highly variable and not diagnostic.
True
Apart from sudden neurologic disease caused by WNV in horses, what two other common clinical signs can be seen?
colic or gait abnormalities
muscle fasciculations
While gross lesions are not always visible with WNV, encephalomyelitis and _________ in the spinal cord, midbrain, or medulla can occur.
hemorrhage/congestion
List 2 main diagnostic tests used for WNV.
IgM antibody capture ELISA
serum neutralization
