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72 Cards in this Set

  • Front
  • Back
for what does arbovirus stand?
arthropod-borne virus
are arboviruses normally enveloped or not?
typically, what type of nucleocapsid do arboviruses possess? What type of genome?
icosahedral; +ssRNA
are all togaviruses and flaviviruses arboviruses?
no, some are not such as rubella and Hepatitis C
what is the intrinsic incubation period of the arbovirus? How long is it?
the human incubation period; usually a week or longer
what is the extrinsic incubation period of the arbovirus? How long is it?
the mosquito incubation period; 14 days
is the mosquito ever harmed by the arbovirus?
can an arthropod transmit an arbovirus to its progeny? Via which route?
often, but not always; transovarian
where are most arboviruses located?
in the tropics
what is the only serious arbovirus disease in the USA? Which 5 viruses are responsible?
encephalitis; Eastern equine encephalitis, Western equine encephalitis, St. Louis encephalitis, West Nile virus, and the California group of encephalitis viruses
from what does the iniitial viremia in arboviral encephalitis stem?
multiplication in vascular endothelium
what is the disease progression of arborviral encephalitis? What is the treatment?
brief febrile malaise followed by encephalitis with paralysis, coma, and death; no specific treatment available.
which of the encephalitic arboviruses causes the most severe arboviral encephalitis?
Eastern equine encephalitis
does Eastern equine encephalitis affect adults or children more? In addition to humans, which animal is also targeted by the virus?
children; horses
which species are dead-end hosts for Eastern and Western equine encephalitis viruses? In addition to mosquitos, which animal is crucial for the propogation of the virus?
horses and humans; wild birds
what are 2 good hints of impending Eastern equine encephaitis epidemic?
excessive rainfall and abnormally high mosquito populations
what are the 2 standard control measures against Eastern equine encephalitis?
reduction of mosquito population and avoidance of mosquitoes during epidemic
St. Louis encephalitis virus and West Nile virus are both members of which virus family? Are they antigenically similar?
flavivirus; yes
in which population are SLE and WN viral infections mostly fatal?
why are humans considered dead-end hosts for SLE and WN viral infections?
they rarely have viremia high enough to infect mosquitos
how are SLE and WN viral epidemics maintained?
via bird->mosquito->bird cycles
to which region of the world is SLE indigenous? WN virus?
North America; North Africa and Middle East
of Eastern encephalitis, Western encephalitis, WN virus, SLE, and LaCrosse virus, which is the most fatal?
Eastern equine encephalitis
what kind of birds are responsible for maintaining an epidemic of Eastern and Western equine encephalitis? SLE and WN virus?
wild birds; domestic and wild birds
Eastern and Western equine encephalitis are both members of which viral family?
are arboviral epidemics in the temperate regions of longer or shorter duration than those in the tropics?
what are 2 diseases, other than encephalitis, that are attributed to arboviral infections?
yellow fever and dengue fever
is dengue fever usually life-threatening? What are the symptoms?
no; fever, severe headache, muscle and joint pain, rash
what is the incubation period for dengue fever? Where is it most commonly found?
1 week; in the tropics and subtropics, especially SE Asia and Caribbean islands
how many different antigenic types of dengue virus exist? Do they cross-react?
4; yes
are humans dead-end hosts for dengue viral infections?
what symptoms characterize dengue hemorrhagic fever? Is this seen more in the native or visiting population?
hemorrhage, vomiting blood, and shock; native
what is the underlying mechanism behind hemmorhage in dengue hemorrhagic viral infections?
macrophage infection causes increase in lymphokines and cytokines which causes hemorrhage
how long is the incubation period for yellow fever?
5 days
where does yellow fever virus first multiply in the host? Where does it spread from there?
vascular endothelium; liver and other organs
what symptoms characterize yellow fever?
fever, nausea, jaundice
in addition to the liver, where does yellow fever viral multiplication occur?
in spleen and kidney
are there subclinical infections of yellow fever? Is the mortality for yellow fever high?
yes; high
where is yellow fever found now?
in rural tropical Africa and South America
which species of mosquito is the arthropod host for dengue and yellow fever?
Aedes Aegypti
other than mosquitoes, which animal is responsible for the spread of jungle yellow fever?
Is there a vaccine available for yellow fever? What type of vaccine is it?
yes, D17; live-attenuated
what is the risk of an unvaccinated person entering during a yellow fever incubation period? Where is this a problem right now?
the virus may spread to the mosquitoes then to the susceptible population; in the southeastern US
what are vertical infections? Horizontal infections?
infections transmitted from mother to progeny; all other infections
what are the 2 pathways that lead to vertical infections?
perinatal and transplacental
which viruses are perinatally acquired?
HBV, HIV, herpes simplex type 2
what are the implications of transplacental infections? What are 4 examples of viruses transmitted in this manner?
they can result in congenital abnormalities due to interference with normal development; parvovirus B19, rubella, cytomegalovirus, and lymphocytic choriomeningitis
are embryonic cells and embryos good hosts for viral growth?
yes, but this is prevented by the placenta
how do transplacental infections cross the placenta?
by replicating in placental tissue
what are fetal defense mechanisms against viral infections?
maternal IgG, fetal Ab after 4th month, inteferon, and cell-mediated immunity
are parvovirus virions enveloped? What is their capsid symmetry? Their genome?
no; icosahedral; linear ssDNA
what is the route of infection of parvovirus B19?
inhalation of a respiratory aerosol from the resp tract of an infected person
what are the symptoms of a parvoviral infection?
atymptomatic or fever, malaise, rash called erythema infectiosum
what is the likely cause of the rash which presents in parvoviral infections?
deposition of immune complexes in capillaries
for which cell type does parvovirus B19 have a tropism? What impact does the initial infection have on the host?
erythroid precursors; inhibition of RBC production for about a week
how well do normal people tolerate the cessation of RBC production in parvoviral infections?
just fine
what occurs during the beginning of a parvoviral infection in hosts with a pre-existing deficit in red blood cell production or a pre-existing abnormally high rate of red cell destruction?
they will have a transient aplastic crisis which can be fatal without transfusions
what chronic condition can result in patients that are unable to fight the parvoviral infection? What treatment is used for these patients?
prolonged anemia; immunization with pooled IgG
what is the most common symptom in primary parvoviral infection?
acute arthritis
what symptom is unique to first- and second-trimester parvoviral infections in developing fetuses?
hyrops fetalis
to what family of viruses does rubella belong? It is transmitted via arthropod infection?
togavirus; no
how is rubella virus transmitted?
by respiratory aerosols from the resp tract of an infected person. Local multiplication in the resp epithelium is followed by viremia
which is more contagious, rubella or measles virus?
measles virus
how long is the incubation period for rubella virus? Is rubella ever subclinical?
18 days; yes
how long does the rubella rash last? What other symptoms are present at this time?
3 days; fever and lymphadenopathy
when, in relation to the rash, is rubella virus excreted from the respiratory tract?
one week before and after the rash
what symptom of severe rubella viral infections is seen in adults?
transient arthritis
what congenital anomalies can result from a transplacental rubella infection?
cataracts, heart defects (patent ductus arteriosus), deafness, retardation
does deafness associated with congenital rubella worsen during life?
yes, it may not be obvious at birth but becomes progressively worse in early years of life
what is the main purpose of the live rubella vaccine?
to prevent congenital rubella
in addition to children, who else should receive the rubella vaccine?
seronegative women of child-bearing age
is rubella still a public health problem in developing countries?