Clinical Aspects Of Vector-Borne Viral Infections

Front 1

West Nile
-type of virus
-vector & reservoir
-transmission (other means)

Back 1

-Flavivirus (mosquito-borne)
-Bird reservoir
-Can have transmission via blood transfusion, organ transplantation, transplacental

Front 2

West Nile
-clinical manifestations

Back 2

Most are asymptomatic
-either West Nile Fever or West Nile Neuroinvasive Disease
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West Nile Fever
-abrupt onset fever, headache, fatigue, myalgia (neck pain/stiffness)
-rash: trunk --> extremities
-can have debilitating post-illness fatigue
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West Nile Neuroinvasive Disease
-encephalitis, meningitis, polio-like flaccid paralysis

Meningitis
-WNF + meningitis
-can get CN palsies
-WBCs in CSF but not as much as w/ bacterial
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Encephalitis
-older, immunocompromised pts
-neurologic sequelae = movement disorders/extrapyramidal
-significant mortality rate and permanent neurologic defects
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Flaccid Paralysis
-asymmetrical, > 1 limb
-permanent weakness or prolonged recovery

Front 3

West Nile
-diagnosis (2 methods)

Back 3

Serology
-look for IgM in blood or CSF

PCR
-serum or CSF

Front 4

Dengue
-clinical manifestations (4)

Back 4

Humans are reservoir hosts (unique)

commonly asymptomatic

undifferentiated fever, dengue fever syndrome, dengue hemorrhagic fever, dengue shock syndrome

Front 5

Dengue
-undifferentiated fever
-dengue fever

Back 5

mild febrile illness in young kids, unremarkable recovery
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-older kids, adults - high fever, headache, retro-orbital pain, mylagias, arthralgias, diffuse rash, petechia/brusing/tourniquet sign
-no plasma leak or severe hemorrhage

Front 6

Dengue
-dengue hemorrhagic fever
-dengue shock syndrome

Back 6

Hemorrhagic manifestations
-skin hemorrhages, gingival/nasal/GI bleeding, hematuria
-thrombocytopenia
-plasma leakage (higher hematocrit, ascites, pleural effusion)
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-DHF + circulatory failure (narrow pulse pressure, hypotension)
-precursor to death - prompt tx!

Front 7

Dengue
-phases of hemorrhagic fever

Back 7

Febrile --> plasma leak --> reabsorption (end of plasma leak)

Can get fluid overload if fluid resuscitation isn't decreased

Front 8

Dengue
-diagnosis

Back 8

Tourniquet test

Acute phase - virus detection
-PCR blood, CSF
-antigen detection

Serology
- only (+) 5 days post-onset --> PCR first!

Front 9

Yellow Fever
-clinical features

Back 9

-High fever, severe BACK myalgias
-Conjunctival suffusion (hyperemia)
-Faget's sign (fever w/o HR increase)
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disease is biphasic - can get recurrence of symptoms
-hepatitis, jaundice, renal failure

Severe hemorrhaging - death from shock/organ failure

Front 10

Yellow Fever
-diagnosis

Back 10

Serology - IgM is detectable when symptomatic

Can be cross-reactive w/ other flaviruses

Front 11

Chikungunya Virus
-type of virus
-vector
-endemic area

Back 11

Togavirus, mosquito vector, endemic in Africa - spread to Indian Ocean islands, India

Front 12

Chikungunya Virus
-clinical features

Back 12

Can be asymptomatic

Can get debilitating polyarthralgias

Febrile illness w/ severe arthritis that can be chronic, debilitating

Front 13

Arbovirus

Back 13

require blood sucking arthropod in life-cycle
-Togaviruses (Chikunguyna)
-Flavivirus (Dengue fever, Yellow fever, West Nile)

Front 14

Vectors
-West Nile
-Dengue
-Yellow Fever
-Chikungunya

Back 14

-Culex (mosquitos)
-Aedes (mosquitos)

Front 15

Define
-enzootic
-epizootic
-vector
-reservoir
-arbovirus

Back 15

Enzootic = pathogen endemic in non-humans

Epizootic = higher than average occurence of a disease/pathogen in non-humans

Vector = live organism that communicates disease

Reservoir = location/object serving as continuous source of disease

Arbovirus = arthropod-born virus (require blood-sucking arthropod to complete life cycle)

Front 16

Vector Borne Disease System
-components

Back 16

Suitable ecology, pathogen, natural host (reservoir), vector
-all most occur together in time/space for epizootics or epidemics to occur

Front 17

Arborvirus Transmission Cycle
-general
-role of ecology

Back 17

Mosquito vector transmits to bird (vertebrate reservoir)
-this is sylvactic AKA natural
-transmission to humans is accidental
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Weather/climate and other aspects of ecology (predators, food, resources) can impact vector/reservoir population sizes

Front 18

Enzootic cycle
-spillover

Back 18

Enzootic = virus cycles from arthropod vector to non-humans

Spillover from enzootic cycle --> humans
-amplification --> tangential transmission (enzootic or bridge vectors)
-humans enter sylvatic enzootic habitat

Some viruses exploit domestic animals w/ rural epizootic cycle
-amplificaiton in domestic animals --> rural epidemics