Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
50 Cards in this Set
- Front
- Back
all of the arbo virus are spread by what? what is the exception. when are these viruses spread
|
mosquitoes, except colorado TICK fever
**spread in summer/fall Arbovirus means ARthropodBOrn |
|
what diseases so arbovirus cause? how do we treat
|
1. Aseptic meningitis- fever, HA, stiff neck, mild disease
2. Encephalitis- seizure, altered mental status, pararlysis we CANOT combat the arbovirus, we can only prevent (wear bug spray, stay inside etc) 3. meningoencephalitis- combination |
|
what are some general features of arbovirus (genome, structure, transmission, hosts)
|
RNA
enveloped, inactivated by solvents from mosquito bite infect lots of things like birds and small animals, we are usually dead end hosts **the arbo are are transmitted the same but lots of vairation in structure and gemone expression/replication |
|
ok so an arbo can cause meningitis, encephalitis or a combination, what determiens the outcome
|
1. specific viral agent
age of pt 3. extent of encephalitis **mostly infections are subclinnical- flu like with no CNS. **in severe causes there is sudden fever, vomit, HA, vertigo etc. cant recover or not- 50/50 |
|
what is recovery after arbovirus
|
ehh, you might you might not
Kids- deafness, psychomotor diffuculty, learning disability **recall polio- paralysis worst at 2-3 days then recover was max at 6 weeks |
|
how is arbovirus dx
|
ehh, often its not. (not the specific virus)
**epidemics create high index of suspicison **IgM AB detection- test CSF or serum with elisa |
|
tell me about IgM AB capture with arbovirus
|
use ELISA, lots of cross talk
**test CSF is best but perhaps can just get serum (serum + may not indicate whats going on it spinal cord) **test for AB EARLY! and look for 4x increase in titer |
|
ok so we can run IgM ELISA to test for arbovirus adn look for 4x increase in titer, what about viral cultures
|
not usually done for arbo virus
**collect specimen early |
|
for what arbovirus is an indirect AB test good?
|
colorado tick fever, (common in transfusions)
BHK21 cells are infected and stained with AB |
|
other than IgM elisa and indirect AB test, what else can be dont to detect arbovirus
|
reverse transcriptase PCR
**keep in mind only a minority of cases have hte exact virus ID |
|
how are arboviruss monitored In the environment
|
mosquite trapping (or bird but its harder)
**when its high in them its likely a human will get it |
|
what are hte dx clues for an arbovirus
how do we treat |
time- season (late summer/fall)
place- endemic area person- 90% its a person under 30 **no tx for arbovirus (viral meningoencephalitis) supportive measures only |
|
arbovirus encephalitis resevoire
|
zoonotic diseases, WIDE resevoire- mostly mosquitoes, vertebrates, rodents, birds, amphibians (crocidile)
humans are typically a dead end host |
|
what type of virus uses arthropod as a TRUE biological vector
|
arbo
Virus infects and multiplies in gut, disseminates in the hemolymph, and ultimately establishes a persistent infection in the salivary glands where it may be transmitted. infected vestor shows no disease nad no amplification of virus occurs here |
|
tell me about arbovirus amplificaiton
|
wont happen in the vector BUT>..
say there is a bird nad mosquitoes feed on it. the bird is uninfected and gets bit by an infected mostuito, the bird is now infected and can pass the virus along to uninfected mosquitoes that feed on that bird |
|
arbo epidemics are associated with what
|
seasionality- late summer/fall. changes each year
**large vector pops--> increased disease |
|
describe the sylvatic cycle of arbo virus
|
from a mosquito to a bord and back and forth- the mostioto accidently passes it to us. we are dead end host for the virus.
*we are accidental host, amplification will NOT occur in us (contrast to urban where a human can pass back to mosquito) |
|
what is the urban cycle associated with arbo virus
|
lots of humans and lots of mosquitoes
**humans have enough viremia to sustain life cycle. human--> mosquito--> human. st louis encephalitis, yellow fever **contrast to sylavatic cycle where humans were dead end |
|
what type of cycle do ellow fever and st louis encephalitis have
|
urban- humans have sustained viremia and are part of cycle
**contrast to sylvatic where humans are dead end accidnetal hosts |
|
can we prevent arbo virus
|
not with vaccine- they are in SO many other things than humans so vaccine wont work
**best thing to prevent it to stop chain of transmission 1. kill the vector 2. avoid exposure 3. immunization of horse/pig NON HUMAN AMPLIFYING HOSTS |
|
so we prevent arbo we can control arthropod vectors, prevent exposure and vaccinate amplifying hosts t or F
|
True
|
|
what is the family, structure, etc of arbo
how it inhibits host |
todaviridae group (toga= cloak= enveloped)
ss + RNA Hemagluttinin is in envelope Repliacated in cytoplasm (like LCMV- rodents) causes pathology in host bc it stops translation of mRNA |
|
what are hte 2 basic groups of hte togavirus
|
togavirus- arbo
1. Alpha EEE, WEE, VEE 2. Flavivirus St louis, West Nile, Yellow fever **LOTS of cross talk, IgM tests are hard to intrepret |
|
wht virus causes california encephalitis
|
Bunyaviridae
ss - RNA envelope (all arbo) |
|
tell me about EEE (eastern equine encephalitis)
where when who |
Eastern US (N and S)
summer fall (June-Oct) **in Fl its all year! SUPER deadly but not very common **less than 15 yo, older than 55 **swamp **often inapperant |
|
a person from Rhode Island got encephalitis in July. The pt was 10 and his 80 yo granddad got it to after fishing in a swamp
which one? what vector? resevoire? |
EEE- eastern, fall/summer, extremes of age
Resevoir: horse, bird Vector: mosquito* needs bridge vector bc the mosquite that spreads it is only a bird one ** |
|
which arbo has a high case fatality rate,
who where vector, resevoire |
EEE
1. old, young, in the east, swamp, summer/fall 2. vector- mosquito (bridge vector) resevoire- horse, bird **young children have better survival than adults **concern that more mosquite spp will increase infections |
|
which encephalitis wiped out turkey farms
|
EEE- old and young, swams, horse/bird/mosquite.eastern, fall/summer
|
|
whats WEE
where when resevoire vector who |
west of Mississippi, irrigated pastures, flooded grounds (no fish)
Summer Fall: wont see it then it explodes Resevoire: bird, horse, small mammal Vector: mosquito KIDS under 10 (most often subclinical) |
|
what disease affects kids in a burst where there are flooded pastures
|
WEE
mosquito- bird, horse, small mammal |
|
in what disease are horses huge in the amplification process nad we shoudl prbly vaccineate them
|
Venezuelan Equine Encephalitis
**benign usually but with outbreaks with apparent disease. most human VEE have apparent disease **disease of "place" central/sounth america, texas, everglades. *soliders **spread until the horse dies |
|
whats VEE
|
ususally benign but thwn a horse gets it it can be HUGE for amplification. ppl get it til the horse dies
infection of place- texas, everglades, central/S america **horse is amplifier |
|
what is venezuelan Equine Encephalitis
|
benign usually- can have outbreaks
Rapid spread til horses are dead or we get dry enough weather that the mosquitoes die Central/S america, US everglades, texas **horses are amplifying hosts **most human VEE infections result in apparent disease |
|
what is st louis encephalitis
where, when? who |
wide distrubution, conc in Midwest US and california (Oh/MS river basin, gulf coast)
Summer Fall (aug/sept) can have seasons with HIGE numbers of outbreaks and then just a few aaffects adults over 40 **bird resevoire, mosquito vector |
|
what encephalitis effects adults over 40 in the summer where there is lots of agriculture and ppl are low SES and hand out outside inthe evening
|
st louis encephalitis
Bird resevoire , mosquite vector |
|
if you have a honkey tonk 40 yo who likes birds and hangs out outside in the summer evenings in your home in OH/MS what encephalitis are you at risk for
|
st louis
low ses, hang outside in evening, agriculture places (OH/MS/CA) |
|
tell me a bit about west nile virus
who is at greatest risk common in US |
largest risk is old ppl (>50)
not common, its an EMERGING disease (not known how long its been here) **neuroinvasive paralytic syndrome simliar to poliomylitis |
|
west nile gives encephalitis simliar to what other neuroinvasive disease
|
poliomylitis
|
|
what is the west nile virus transmission cycle
|
bird resevoir --> mosquito vector
**the mostoito can then infect us and livestock as indicental infections |
|
how is west nile dx
|
IgM ELISA with serum or CSF- lots of cross reaction with St Louis or Yellow fever
**plaque reduction neurtralization test may be used to confirm |
|
what % of west nile infections result in disease
*8what predisposes you to getting the bad effects |
20%
About 1:150 total infections result in severe neurological (neuro-invasive) disease Most important predictive factors for severe disease/death is advanced age (>50 years) or immune system dysfunction |
|
The flaccid paralysis syndrome (West Nile poliomyelitis) is _____ (more or less) common than encephalitis or meningitis
|
less
|
|
who might you suspect has west nile virus
|
Consider WNV in any patient with unexplained encephalitis or meningitis
|
|
what does it mean if a person has IgM west nile + in serum but - in CSF
|
well we get lots of cross talk so a + serum can be a recent infection/vaccination against st louis or yellow fever
**CSF is only + if the infection is in the CSF- IgM cant cross BBB |
|
what is the most important cause of mild encephalitis, what serotype are most cases caused by
|
california encephalitic, most common by LaCrosse serogroup
|
|
who is affected by california encephalitis
|
summer/fall
school ages boys **commonly caused by LaCrosse serogroup **important cause of mild encephalitis- daytme mosquite feedings |
|
what is the reservoir for california encephalitis
|
small mammels
**mosquitoes are the vector as with ALL arbo virus. there is daytime mosquito feedings |
|
what arbo is common in NW US
|
CO tock fever
reovirus, with 12 segments of ds RNA |
|
what arbo has a sadlebacked fever pattern (up and down)
|
colorado tick fever
**most individuals have a history of tick sttachment or exposire March- Oct in mountinous regions of NW US |
|
what arbo virus has restrictions on blood donations
|
colorado tick fever, dont donate for like 6 months after infection (virus seeds progenitor cells)
**recall its a reovirus with 12 segemnts of dsRNA, common in NW US |