Arboviruses
Microbiology 1 with Swierkosz at Saint Louis University
About this deck
By: Brian Nguyen
Created: 2011-03-08
Size: 21 flashcards
Views: 3
Created: 2011-03-08
Size: 21 flashcards
Views: 3
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Enzootic transmission
Regular cycle of virus between vector and maintenance host
Virus causes persistent infection in salivary glands
Epizootic transmission
Transmission of virus between vector and vertebrate that isn't its normal maintenance host.
Viremia may be too low to sustain transmission
Dead-end host may or may not become sick
Urban epidemic cycle
Stable transmission between viremic human to vector without another vertebrate host
Rare, but can be established by yellow fever and dengue virus
Human involvement in arbovirus transmission cycles
Urban epidemic cycle
Spillover from epi/enzootic cycle
Effect of obligatory 2-host replication cycle on viral biology
Increases viral persistence and viral control through vector control
Reduces variability in viral genetics - reduce genetic drift and yield tighter quasispecies clouds
Medically relevant arbovirus families
Togaviruses, flavivirus, bunyavirus
Key Flavivirus arboviruses
Yellow fever, dengue, St. Louis encephalitis, west nile virus
Yellow Fever epidemiology, infectious cycle, disease
Mosquito borne
Tropical S/Central America, Sub-Saharan Africa
Jungle cycle (enzootic w/ monkeys), (epizootic sporadic human)
Urban cycle - self sustaining epizootic
Causes jaundice and hemorrhagic fever
High mortality rate
Yellow Fever Virus pathology
Biphasic
1st phase HA, fever, chills, nausea
hallmarks - head/neck flushing, strawberry tongue, Faget's sign (fever + bradycardia)
Most cleared, 2nd phase more serious
fever hematemesis prostration bleeding jaundice (2nd tropism for liver)
shock death
Yellow fever dx, treatment, prevention
Detection of increase in serum Ab or viral antigens in serum
Fluid replacement, antacids, avoidance of salicyclates
Prevention - vector control and live attenuated vaccine
Dengue virus characteristics, disease
Present in tropical locations, most important arboviral cause of death
Mosquitoes with human reservoir
4 serotypes, antigenically related but distinct
causes 2 disease: classic dengue fever, dengue hemorrhagic fever/shock syndrome
Classic dengue fever
break-bone fever
suddent on set of flu-like symptoms, macular rash, nausea/vomiting, severe muscle/bone pain, arthralgia
complete recovery after 6-7 days
Dengue hemorrhagic fever
Biphasic, common in <15y.o.
1st phase classic dengue fever
2nd phase immune mediated, concurrent infection with more than 1 serotype
Abs to one type bind to other type and concentrate it around macrophages to further infection
Profound prostration, circulatory collapse, dermal and mucous membrane bleeding, hemorrhagic pneumonia
Dengue fever virus dx, treatment, prevention
Dx from symptoms of fever, hemorrhagic tendency
Confirm with molecular techniques, RT-PCR
Treatment - supportive care, limit bleeding
Prevention - vector control, vaccine under development
St. Louis Encephalitis virus
Most common arboviral cause of encephalitis in the US
Mosquito, bird (sparrows) cycle
More common in kids, febrile headache to encephalitis
No antivirals, no vaccine
West Nile virus
Endemic worldwide, introduced to US
Mosquito, bird cycle
highly pathogenic in crows
Common in adults, esp elderly
Flu-like symptoms, 1% develop meningitis or encephalitis
Supportive therapy, no vaccine no antivirals
Key Togavirus arboviruses
Eastern equine encephalitis, western equine encephalitis
Eastern equine encephalitis
Mosquito vector, affects humans and horses
Young and elderly more affected
Prodromal - fever, HA, myalgia, photophobia, numbness
Neurological - frontal HA, dizziness, lethargy, then neck stiffness confusion cerebral edema
Most sever arboviral encephalitides - 30% mortality, 50% survivors have permanent brain damage
Dx IgM in CSF
No antivirals or vaccine (except for horses)
Western equine encephalitis
Like EEE, but less severe
Neuro symptoms limited to convulsions, weakness, general tremulousness
Young pts at risk
3% mortality, permanent brain damage in 5-30% of patients
No antiviral or vaccine (except for horses)
Key bunyaviruses
La Crosse Encephalitis, Chikabunya virus
La Cross Encephalitis
Endemic in midwest, relatively rare
Mosquitoes to chipmunks/squirrels
disease - subclinical or mild
Can cause encephalitis, <1% fatality
No antiviral or vaccine
About this deck
By: Brian Nguyen
Created: 2011-03-08
Size: 21 flashcards
Views: 3
Created: 2011-03-08
Size: 21 flashcards
Views: 3
About StudyBlue
STUDYBLUE makes things that make you better at school.
Things like online flashcards with photos and audio.
Things like personalized quizzes and friendly reminders about when (and what) to study next.
Think of it as a digital backpack™: access to all of your study materials online and on your phone.
STUDYBLUE exists to make studying efficient and effective for every student, for free. Join us.
“I have been getting MUCH better grades on all my tests for school. Flash cards, notes, and quizzes are great on here. Thanks!”
Kathy
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