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Flashcards in togaviridae Deck (22)
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1
Q

togaviridae classification

A

genus-alphavirus (arthropod borne)

genus-rubivirus (rubella)

2
Q

togaviridae morphology

A

linear single stranded + sense

3
Q

Alphaviruses

A

Western equine encephalitis (WEEV)
eastern equine encephalitis (EEEV)
venezuelan equine encephalitis (VEEV)

4
Q

EEEV distribution

A

zoonotic by mosquitos in easter NA carribbean and central america, encephalitis in horses and humans, 4 lineages, 1 is in NA, other (II, III, IV) are less virulent

5
Q

EEEV transmission

A

epizootic involves birds and mosquitos that transmit to pheasants or dead end hosts
enzootic transfers to marsh birds or reptiles/rodents

6
Q

Path EEEV

A

mosquito bite-enters CNS through hematgenous route, replication in neurons and glial cells, apoptosis, non suppurative encephalomyelitis

7
Q

EEEV in horses

A

fever, anorexia, depression, hypersensative to sound, colic, walk blindly, can’t hold up head, leaning back, cannot hold up head

8
Q

EEEV in humans

A

most cases no apparent illness,
systemic form-arthralgia, myalgia, no CNS
Enceph form-anorexia, vomiting diarrhea cyanosis, convulsions
prognosis- 30% die, recovered may have permanent brain damage

9
Q

EEEV in birds

A

asymptomatic, tremors, leg paralysis, involuntary circular movements

10
Q

WEEV

A

may have emerged from EEEV genetic recombination, found in NA and SA, NA strains more virulent, WEEV lower fatality and less virulent than EEEV

11
Q

WEEV cycles of transmission

A
enzootic (Culex)-house sparrow or house finch amplifying hosts 
epizootic vector (Aedes)- rodents including prairie dogs and rabbits
12
Q

WEEV horses clinical signs

A

mild or asymtomatic mostly, otherwise show symptoms of EEEV

13
Q

WEEV humans clinical signs

A

mild or asymptomatic, infants are highly susceptible

14
Q

Venezuelan Equine Encephalitis virus

VEEV

A

epizootic (highly virulent for equines)-I-A, I-B, I-C subtypes
enzootic-not virulent for horses I-D, I-E, I-F subtypes

15
Q

VEEV enzootic cycle

A

Culex primary vector with rats and Aedes; horses and humans accidental hosts

16
Q

VEEV epizootic cycle

A

mosquito to horses, accidental host humans (dead end)

17
Q

mutation of endemic strains

A

can become epidemic strains, 1AB virus may arise from mutation of endemic strains (1D-F)

18
Q

clinical signs VEEV

A

non-suppurrative enchephalomyelitis, in-utero infection may occur, same signs as EEEV (leaning stance, lack of coordination, dead horse)

19
Q

humans clinical signs VEEV

A

normally acute, mild, systemic disease, encephalitis symptoms
*may cause placental damage in pregnant women, or fetal encephalitis, or abortion/stillbirth, or congenital disease

20
Q

control of all forms EEV

A

mosquito control-repair leaky faucets, cover rain barrels, change stagnate water sources,, etc.
can use mosquito traps, report dead birds, use chicken serology testing, use natural enemies, incesticides
wear protective clothing, insect repellants, nets

21
Q

vaccination in horses

A

formalin inactivated for WEEV and EEEV univalent or bivalent with tetanus toxoid

22
Q

vaccination in humans

A

no vaccine