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59 Cards in this Set

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ARBOVIRUS

Three key properties of "Arbovirus"
1.) Transmitted btw vertebrate hosts by the BITE of infected hematophagous arthropod

2. Multiply AND Produce Viremia in vertebrate host

3. Multiply in the tissues of arthropod vectors.
ARBOVIRUS

T/F : Arbovirus is a TAXONOMIC classification!
- False

- It is an EPIDEMIOLOGICAL classification
Describe the virion envelope for the following virus families:

- Flaviviridae
- Togaviridae
- Bunyaviridae
ENV - 45 nm

ENV - 60 nm

ENV - 80 to 120 nm
Describe the matrix for the following virus families:

- Flaviviridae
- Togaviridae
- Bunyaviridae
YES

YES

NO
Describe the Nucleocapsid for the following virus families:

- Flaviviridae
- Togaviridae
- Bunyaviridae
ICOS

ICOS

Variable
Describe the packaged enzymes for the following virus families:

- Flaviviridae
- Togaviridae
- Bunyaviridae
NONE

NONE

RNA-Dependent RNA PY
Describe the genome for the following virus families:

- Flaviviridae
- Togaviridae
- Bunyaviridae
ssRNA

ssRNA

ssRNA
Describe the genome sense for the following virus families:

- Flaviviridae
- Togaviridae
- Bunyaviridae
Positive

Positive

Negative/Ambisense
Describe the number of segments for the following virus families:

- Flaviviridae
- Togaviridae
- Bunyaviridae
Nonsegmented
(1 molecule)

Nonsegmented
(1 molecule)

Segmented
(3 segments)
Describe the replication strategy for the following virus families:

- Flaviviridae
- Togaviridae
- Bunyaviridae
Positive

Positive

Negative/Ambisense
Describe the first step in replication for the following virus families:

- Flaviviridae
- Togaviridae
- Bunyaviridae
Genome translated to polyprotein

5' 2/3rd genome translated to polyprotein

Positive sense copy of genome tranSCRIBED
Describe the subgenomic RNAs for the following virus families:

- Flaviviridae
- Togaviridae
- Bunyaviridae
NONE

YES

YES
What are the factors influencing Epizootic/Epidemic outbreaks? x5
COMPETENCE for enzootic & epizootic vectors

ABUNDANCE of enzootic & epizootic vectors

HUMAN behavior

ABUNDANCE of vertebrate reservoir hosts

Genotype of virus
(e.g. - virulence mutations)
Commonalities between arbovirus infection of humans:

- what kind of inoculations
- inoculation by?
- typical "dead end" host
- exceptions to "dead end" host? x2
SubQ

Arthropod vector

Dead-End ==> Human Host (mostly)

Denque & Yellow fever virus
(exception)
Commonalities between arbovirus infection of humans:

- MOST symptoms are?
- Common symptoms involve?
- Prognosis of common Sx?

- Earliest symptoms
- Severity of disease dependent on what?
Asymptomatic***

BIPHASIC FEBRILE ILLNESS

Resolve without complication

Flu-like (fever, HA, malaise, myalgia)

Age dependent
(Worse in very young or very old)
ARBOVIRUS ATTACK RATES

- Discuss the RATIO of arboviral infections that is VERY HIGH
Ration of inapparent (ASYMPTOMATIC) to apparent (SYMPTOMATIC)
ARBOVIRUS ATTACK RATES

- Discuss the ATTACK rate
LOW
The usual inability of an arbovirus to establish a symptomatic infection in the host is due to what 2 factors?
- Virus Dosage (NOT genetics)
- Human genetics/IMMUNE response
St. Louis Encephalitis Virus:

- Family
- Genus
- Reservoir Host
- Vector
Flaviviridae

Flavivirus

Avian

Mosquito
St. Louis Encephalitis Virus

- Largest US epidemic # of cases
- Most recent outbreak where?
- Affects what US states? x7
2000

Monroe, LA (69 cases)

OH-MS valley, East TX, FL, KS, CO, CA
St. Louis Encephalitis Virus:

- SE US seroprevalence
- Symptomatic case fatality
- Symptomatic to infected ratio
- Symptomatic to infected ratio in elderly
- Epidemic attack rate
~6%

7% (age-dependent)

1:800

1:85

Less than 1:100
West Nile Virus (Old World):

- Family
- Genus
- Reservoir Host
- Vector
Flaviviridae

Flavivirus

Avian

Mosquito
West Nile Virus (Old World):

- "Hyperendemic" where?
- High seroprevalence precludes what?
- Eventual decline of endemic transmission would do what?
Africa and Middle East

Epidemic outbreaks

Increase risk of epidemic
Why do most West Nile virus symptoms go unrecognized?
Clinically undifferentiated from febrile disease in children
West Nile Virus in low immunity areas.

- epidemic attack rate
- severity of symptoms
- mortality rate
- CNS infection?
60%

Mild

Very LOW

RARE
Eastern & Western Equine Encephalitis Virus:

- Family
- Genus
- Reservoir host
- Vector
Togaviridae

Alphavirus

Avian

Mosquitoes
Eastern & Western Equine Encephalitis Virus has the highest rate of impact on children it infect of what symptoms? x3
Encephalitis

Seizures

Sequelae
Eastern & Western Equine Encephalitis Virus comparison:

- average human cases per year
- fatality rate
WEE - 34/year 10% fatality
EEE - 7/year 30-70% fatality
Eastern & Western Equine Encephalitis Virus comparison:

- Case to Infection ratio for children
WEE: 1:50 in children < 5 yr

EEE: 1:8 in children < 10yr
Eastern & Western Equine Encephalitis Virus comparison:

- Case to Infection ratio for adults
WEE: 1:1000

EEE: 1:23
Eastern & Western Equine Encephalitis Virus comparison:

- Sequelae
WEE: 5% of survivors

EEE: 35-80% have permanent neurologic impairment.
ARBOVIRUS INFECTIONS

- what are the "commonalities" x7
D ASS ERA

- Dead end host is humans
(except in DEN & YFV)

- Asymptomatic usually
- Symptomatic is Biphasic Febrile Dz
- SubQ inoculation by arthro-vector

- Early Sx is "flu-like"
- Resolves usually without complications
- Age dependent severity
ARBOVIRUS INFECTIONS

- what does it mean that humans are "dead end hosts?"

- why?
- No further transmission from humans
(after getting it from arthropod vector subQ)

- b/c LOW dosages in blood
(not related to viral genetics)
(although, human genetics may play a role)
ARBOVIRUS INFECTIONS

- Worse Dz & Higher mortality in whom? x2
Age Dependent Severity, so

- Very young
- Elderly
ARBOVIRUS INFECTIONS

- Attack rate (Sx:ASx) in those infected

- why such numbers?
- Low attack rate

- inability of arbovirus to establish symptomatic infection in host
(Due to Virus DOSE)
(Human genetics or Immune response also can play a role)
ARBOVIRAL HEMORRHAGIC FEVER

T/F : AHF is a potentially LETHAL Dz syndrome
True
ARBOVIRAL HEMORRHAGIC FEVER

- Potentially LETHAL Dz syndrome characterized by what progressive Sx? x8
- Fever, Malaise, Myalgia

(progress to)
- Mucosal bleed
- GI bleed
- Vomiting

(progress to:)
- Hypotension
- Edema
ARBOVIRAL HEMORRHAGIC FEVER

- Clinical manifestations begin with what 3 symptoms?

- Progressing to? x4

- Bad news if progressed to? x2
(F CP)

- Flushing
- Conjunctival injection
- Petecial hemorrhage

(Frank @ HSC)
- Frank Mucosal Hemorrhage
- Hypotension
- Shock
- Circulatory collapse

- DIC
- Multi-organ failure
YELLOW FEVER HISTORY

- Last US epidemic in?

- Famous Firsts? x2

- Old world or New world?
- New Orleans, LA in 1905
(>3,000 cases, 452 deaths)

- 1st Filterable Human Pathogen
(Walter Reed)

- 1st Live Attenuated Vaccine - 17D
(Max Theiler - Nobel in 1952)

- Both
(1st reported cases in both in 1600s)
YELLOW FEVER

- Range of YFV expanding to? x2
Re-EMERGENCE in Africa

Re-ESTABLISHMENT in SE USA
YELLOW FEVER

- Describe the Hepatic induced Coagulopathy & Hemorrhagic manifestations. x7
Yellow man BB of GE is full of PEP
- Black Vomit (hematemesis)
- Bloody Diarrhea (melana)

- Gum bleed
- Epistaxis (nasal hemorrhage)

- Petechial hemorrhage
- Ecchymotic hemorrhage
- Purpuric hemorrhage
YELLOW FEVER

- Systemic manifestations x2

- Poor prognosis if?

- what reflects degree of hepatic injury?
- Jaundice
- Albuminuria

- Early Jaundice @ day 3

- Transaminase elevation
YELLOW FEVER

- Late stage symptoms? x6

- Late CNS Sx? x3

- Death is usually when?
MA MASH
- Myocardial Dysf(x)
- Arrhythmia
- Metabolic Acidosis
- Acute Tubular Necrosis
- Shock
- Hypotension

SCC
- Seizures
- Confusion
- Coma

- 7 to 10 days post onset
RIFT VALLEY FEVER VIRUS

- Outbreaks where?
(North & South valley)

- North Africa

- Sub-Saharan Africa
RIFT VALLEY FEVER VIRUS

- In 2000, first reports of RVF virus noted where? x2

- concern b/c
SAY
- Saudi Arabia
- Yemen

- threatens Asia & Europe
RIFT VALLEY FEVER VIRUS

- Primarily affects what reservoir hosts?

- Epizootic outbreaks when?

- Epizootic outbreaks signaled by?
- Livestock
(sheep, cattle, camel, goats)

- Heavy rainfall & Flood

- Abortion Storm in livestock
RIFT VALLEY FEVER VIRUS

- During outbreaks, humans infected in 3 ways?
MBA

- Mosquito vector
- Blood or Body fluid contact
- Aerosolized inhalation
CRIMEAN CONGO HEMORRHAGIC FEVER

- reservoir host
- vector

Endemic where? x3
- Rodents
- Ticks

- Asia
- Eastern Europe
- Africa
CRIMEAN CONGO HEMORRHAGIC FEVER

- recent outbreaks seen where? x5
PIKAS
- Pakistan
- India
- Kosovo
- Albania
- South Africa
CRIMEAN CONGO HEMORRHAGIC FEVER

- During CCHF epizootic, humans infected in what 2 ways?
- Tick bite

- Blood / Body fluid contact
CRIMEAN CONGO HEMORRHAGIC FEVER

- Severity in humans?
- Mortality rate?
- SEVERE Dz in humans

- HIGH mortality rate
CRIMEAN CONGO HEMORRHAGIC FEVER

- Majority of cases in what types of people? x4
SAVE

- Slaughterhouse workers
- Agricultural workers
- Vets
- Etc.....
ARBOVIRAL HEMORRHAGIC FEVER

- For Differential Dx, of paramount importance are what factors? x3

- What is NOT a diagnostic for AHF?
Pre-Coss Pie

- Place of Residence / Exposure

- Community Occurrence & Serodiagnosis of Similar cases

- Prior Infection / Exposure

- Specific Sx is NOT Diagnostic
ARBOVIRAL HEMORRHAGIC FEVER

- Differentials include what? x7
Ladies were Leeping for MORRIS

- Leptospirosis

- Malaria
- Other arbovirus infections causing fever & rash
- Rubella
- Rubeola
- Influenza
- Scrub typhus
YELLOW FEVER VIRUS VACCINE

- called what?
- what type of vaccine what is?

- what YFV strain isolated in 1928

- how did they attenuate it?
- 17D vaccine
- Live-Attenuated vaccine

- Aisibi strain

-Passaged 200 times
in
Mouse Brain
&
Chick Embryo
YELLOW FEVER VIRUS VACCINE

- how did they grow it?

- how did they safety test it?
- Embyonated egg

- Safety test in Monkeys
YELLOW FEVER VIRUS VACCINE

- how many produced annually?

- is this enough?
- 13 million
(11 million used in Brazil)

- Not enough if YFV Re-Emerges
(currently Re-Emerging in Africa)
(currently re-estabishment in SE US)
YELLOW FEVER VIRUS VACCINE

- recommended for?

- contraindicated for? x3
- those traveling to endemic areas

- Pregnant
- Immunosuppressed
- Infants less than 6 months old
YELLOW FEVER VIRUS VACCINE

- is it safe?

- is it efficacious?

- seroconversion rate?

- what type of immunity imposed by vaccine?
- among safest

- among most efficacious

- 96% seroconversion

- Long lasting immunity