Arboviruses and Other Zoonotics

Is it an arthropod vector?mosquito?tick?biting fly?

all Flaviviridae are Arboviruses except Hepatitis C and G

human-human transmission via host?

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

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

Hemorrhagic Dengue Syndrome: Ab against one serotype play a pathological role.2nd atack makes Ab unable to neutralize the virus.

small dermal vessel injuriespetechiae

necrosis

disseminated intravascular coagulation

Target Organs: skin, joints, muscleSx: fever, malaiase, muscle and joint pain, nausea, vomiting

Rash on elbows, knees, chest

nausea, vomiting

1. Replication in target organ2. infection spreads to WBC and lymphatics3. circulates in blood.

perpetual outbreaksvirus persists in mosquito egg for years

Urban Populations

80%

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

meningitisencephalitis1:150 focal necrotic neurons and inflammation10% fatality

resolves over timeascending paralysis including respiratory muscles (ventilation req'd)

initally presents like a strokepermanent paralysisseizures, chorea retinitis, optic nueritis, often results in blindness

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

aligators: high levels of virus

Culex

wild birds

TX, FL, Miss.Urban and Wild (sylvatic)

> 40 yo

CSF or blood difficult (per syllabus) but lecture: Gold Standard=CSF culturecan isolate from brain of dead bird

Gold Standard for West Nile: CSF (spinal tap)

IgM

for WNV: urine PCR in recent use

RES: liver, spleen, lymph nodesreplication in target organs

EncephalitisHepatitisDengue Shock Syndrome

neurological sequelaesevere with high mortalitiy in childrenrural US, NE to Florida, Great Lakes, Central and South America

rural western USmore frequent and less severe than EEEinfants and children

"Venezuelan"= Central and S. Americamainly horsesmild systemic with rare encephalitis

"bends up": musculoskeletal position due to muscle & joint painOther Sx: fever, headache, fatige, rash, nausea, vomiting

important for binding, entering, replicating

broad range: bird, mouse, horse, humanhuman: dead endhigh titer horse can transmit

Culex: WEE Aedes: VEECulisetts: EEE, salt-water marsh mosquito

IgM

early stages of Dengue & Chikungunya;most do not exhibit virus in blood

EEEWEEVEESLE (St. Louis encephalitis)WNVCalifornia encephalitisPowassan encephalitis (European)