4 hallmarks of WNV
Three conditions of WN encephalitis?
West Nile Fever
About __% of West Nile infections are asymptomatic
About __% of patients develop West Nile Fever, from which most people ____
West Nile Fever lasts about ______ days
Hallmark for CNS disease from West Nile VIrus? How many patients progress to this stage?
Erythematous maculopapular or morbilliform rash
Less than 1%
WNV infects ____ cells
WNV vauses primary viremia after migrating to ______
Does WNV cause 2' viremia?
After dissemination to RE system
_____ limits WNV dissemination to the CNS
Patients that progess past this point may have less robust ___ response
_____ results in WNV clearance from infected neurons
CD8 T cell response
WNV major vector and intermediate host
Bird intermediate host
Other than mosquito to man, what are other ways we can and can NOT get WNV?
No: Man to man or animal to man
Yes: Live or dead bird, consumption of infected bird
Other: Blood transfusions, organ transplants, lab exposure, or from Mom > Baby
WNV vaccines are approved for ___
Increased _______ helps in spreading Dengue
Explain the Dengue infection in terms of serotypes and immunity
If infected with one, it does not provide protection against the other three
It actually increases the severity of subsequent Dengue infections
Dengue presents ___ days after bite
Does Dengue cause a fever?
Yes - saddleback fever up to 106 degrees
Most people recover from Dengue within _____
Two Dengue Clinical presentations (syndromes)
- Dengue Hemorrhagic Fever (DHF)
- Dengue Shock Syndrome (DSS)
Most DHF patients are how old?
under 15 years
Characteristic manifestations of DHF
- Plasma leakage
- bleeding from trauma sites
- GI bleed
- Seizures and CNS symptoms
What is DSS?
Dengue shock syndrome - it is untreated DHF that has progressed to circulatory failure
Dengue targets what cells?
Langerhans (dendritic) cells
Dengue pathogenesis (6 steps)
APC to T cells
Enter Monocyte/endothelial cells, attacked by CD4/CD8 and cytokines
activates immune system
- increases vascular permeability (plasma leaks)
Hemoconcentration and hypovolemic shock occur
Dengue is enhanced in an __________ fashion
*they aid virus in getting into cells
sEach DENV (Dengue) serotype has the ability to cause _______ infections
(asymptomatic, DF, DHF, DSS)
______ are most affected by Dengue
Dengue in US occurs primarily in ___________________
travelers from endemic areas
Dengue mainly spread by ______
Aedes aegypti mosquito
Can dengue be transmitted from human to human?
Primate cycle of transmission is called ________
Sylvatic / Enzoonotic
Dengue control and treatment
No treatment (supportive therapy only)
Immunization is hard because of SEROTYPES
Yellow Fever stages
YF initial symptoms
abrupt flu like symtoms (with fever)
YF toxic phase develops after...
initial remission of symptoms and fever
YF toxic phase hemorragic manifestations are caused by...
hepatic induced coagulopathy.
causes hematemesis, epistaxis, gingival bleeding and petechial hemorrhages
YF toxic phase - systemic manifestations?
jaundice and albuminuria
Late stage YF manifestations
- Hypotension, shock
- Metabolic Acidosis
- Acute Tubular Necrosis
- Heart dysfunction and arrhythmia
What distinguishes the CNS symptoms of the late stages of YF?
________ are complications in patients who survive late-stage YF
Secondary bacterial infections
YF replicates initially at ___________
local lymph nodes
Where does YF spread to once initial infection occurs?
First to other lymph tissue, spleen and bone marrow
Then to liver, lungs, and adrenals
Most important organ affected by YF?
______ form in the liver during YF
2nd most affected organ by YF?
What systemic changes result from this?
Albuminuria and renal insufficiency
YF hemorrhage is from reduced _________ and can result in _________
reduced clotting factor production by liver
Results in: Hematemesis, thrombocytopenia, and platelet dysfunction
The terminal event of YF is _____.
What two things can this be attributed to?
from direct parenchymal damage and systemic inflammatory response
Almost everyone that enters the toxic stage of YF...
progresses to the late (third) stage
Yellow Fever Vaccine properties/dosage
Vaccine = Live attenuated (Stamaril)
Single dose gives 100% immunity for 10 years
single SubQ injection
The arboviral togaviridae are...
EEEV, WEEV, VEEV
Alphavirus genome structure
Alphavirus has ______ for attachment
but NO receptor is known!!
Alphavirus replication occurs in _____
Alphavirus parental ___ RNA strand encodes ______.
The resulting molecule is re-coded into _______.
This RNA is made into ___ and _____.
This results in production of ______.
parental +RNA makes Nonstructural proteins in 5' end
Molecule recoded into (-) RNA
Made into progeny +RNA is made into +mRNA
This results in production of progeny virus
EEE has a ____ period first
EEE progresses more rapidly to _____ and ______
CNS and death
CNS symptoms of EEE
General (headavhe, nausea, confusion)
Focal defecits (sensory/motor loss, seizures, stiff neck, cranial nerve palsies, photophobia)
Pathogenesis of EEE
mosquito injects virus subQ
Non-CNS replication during prodrome
2' viremia = CNS invasion
immune cells enter brain and damage
Gross inspection = edema, vascular congestion, hemorrhage, ENCEPHALOMALACIA
Equine Encephalitis' resevoirs
Mosquitos, Birds (WEE and EEE)
*also amphibians and reptiles
Incidence of EEE
only 5% of EEEV results in EEE
What happens immunologically after EEEV infection?
EEEV most common in ____ United States
WEE incubation time
Short (1-4 days)
Initial WEE symptoms are...
subclinical in many people
WEE Neuro symptoms indicate
Symptoms similar to EEE (Focal defecits, seizures, neck stiffness and photophobia)
________ is rarer in WEE than EEE
cranial nerve palsy
WEE is most common during
Summer months (April - September)
VEE presentation can be ___, ___, or ___
MODERATE (+ photophobia back pain, fever)
SEVERE (acute high fever, severe myalgia and back pain, photophobia, prostration, confusion)
In Alphavirus, ____ and ____ are dead end hosts
humans and horses
Alphavirus can be transferred to mosquitos from ____
Alphavirus control is based on _______
Vaccine for Alphavirus? Who is it used for?
used for lab workers
What vaccine has been used for Alphavirus in horses?
live-attenuated VEE vaccine
*similar one used for lab workers