Arboviruses and Othe

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Arboviruses and Other Zoonotics

Arthropod

Is it an arthropod vector?

mosquito?

tick?

biting fly?

vertebrate hosts

squirrels/rodents

monkeys

pigs

birds

Replication

Cytoplasm

hemorrhagic fever

aseptic viral encephalitis

EEE

WEE

VEE

SLE (St. Louis encephalitis)

WNV

California encephalitis

Powassan encephalitis (European)

Diagnostic

RT PCR

early stages of Dengue & Chikungunya;

most do not exhibit virus in blood

ELISA

Families

Togaviridae

Vectors

Mosquito

Culex: WEE

Aedes: VEE

Culisetts: EEE, salt-water marsh mosquito

broad range: bird, mouse, horse, human

human: dead end

high titer horse can transmit

2 glycoproteins

important for binding, entering, replicating

Chikungunya

"bends up": musculoskeletal position due to muscle & joint pain

Other Sx: fever, headache, fatige, rash, nausea, vomiting

VEE

"Venezuelan"= Central and S. America

mainly horses

mild systemic with rare encephalitis

WEE

rural western US

more frequent and less severe than EEE

infants and children

EEE

neurological sequelae

severe with high mortalitiy in children

rural US, NE to Florida, Great Lakes, Central and South America

Flaviviridae

all Flaviviridae are Arboviruses except Hepatitis C and G

Pathogenesis

2' viremia

Encephalitis

Hepatitis

Dengue Shock Syndrome

Ab Block

vascular endothelium

RES: liver, spleen, lymph nodes

replication in target organs

1 glycoprotein

Diagnosis

PCR

for WNV: urine PCR in recent use

EIA

IgM

Serology

Gold Standard for West Nile: CSF (spinal tap)

Culture

CSF or blood difficult (per syllabus) but lecture: Gold Standard=CSF culture

can isolate from brain of dead bird

human-human transmission via host?

Urban Populations

SLV

Powassan

Japanese Encephalitis

St. Louis Encephalitis

aligators: high levels of virus

Population

> 40 yo

Geography

TX, FL, Miss.

Urban and Wild (sylvatic)

Reservoir

wild birds

Culex

WNV

Epidemiology

Transmission

human-human transmission of WNV through blood transfusion, not by vector

Risk

Immunosuppression

HTN

> 50 yo

Sequelae

Neurological Complication

Viromyelitis

initally presents like a stroke

permanent paralysis

seizures, chorea retinitis, optic nueritis, often results in blindness

Guillaume-Barre-like

resolves over time

ascending paralysis including respiratory muscles (ventilation req'd)

WN Neuroinvasive Disease

meningitis

encephalitis

1:150 focal necrotic neurons and inflammation

10% fatality

WN Fever

West Nile Fever (20%): sudden onset mild/high fever, frontal headache, back pain, my

algia, anorexia, rash

asymptomatic viremia

80%

Symptoms

Encephalitis

Rash

Fever

primarily human-human transmission in urban areas... not a dead-end host

Vector

perpetual outbreaks

virus persists in mosquito egg for years

Aedes

Host

Monkey

Systemic illness

Hemorrhage

Yellow Fever

Dengue

prostration, GI & skin hemmorhages, shock , coma, death(10%)

Pathophysiology

1. Replication in target organ

2. infection spreads to WBC and lymphatics

3. circulates in blood.

Characteristics

Classic

Target Organs: skin, joints, muscle

Sx: fever, malaiase, muscle and joint pain, nausea, vomiting

G/I

nausea, vomiting

Joints

Muscle

Skin

Rash on elbows, knees, chest

Dengue Shock (DSS)

Hemorrhagic (HDS)

Hemorrhagic Dengue Syndrome:

Ab against one serotype play a pathological role.

2nd atack makes Ab unable to neutralize the virus.

DIC

disseminated intravascular coagulation

liver

necrosis

skin

small dermal vessel injuries

petechiae

4 serotypes

E. bola

LaCrosse

California Complex Virus

Reoviridae

Colorado Tick Fever

Other Zoonotics

Poxviridae

Filoviridae

Clinical

Marburg

Ebola

Roboviruses

Bunyaviridae