ARBO Viruses

Question 1

ARBO =

Answer 1

arthropod borne viruses

Question 2

ARBOviruses Vectors

Answer 2

Vectors – mosquitos, ticks, sandflies – virus often replicates in salivary glands

Question 3

ARBOviruses Transmission cycles

Answer 3

Transmission cycles –
Man – Arth – Man – dengue and urban yellow fever
Animal – arth – man – Japanese enceph, EEE, WEE, jungle yellow fever

Question 4

ARBOviruses Pathogenesis

Answer 4

– primary viremia from bite → macros, liver, spleen → secondary viremia → BBB cross → neuron death

Question 5

Alphaviruses: Togaviruses Structure

Answer 5

Structure – enveloped ss+RNA, icosahedral, 5’ cap – non-structural proteins – structural proteins

Question 6

Alphaviruses: Togaviruses

Answer 6

VEE – Venezuela equine encephalitis
WEE – western,
EEE – eastern
Chikungunya -

Question 7

Flaviviruses:

Structure

Answer 7

Structure – enveloped ss(+)RNA, 5’ cap – SP - NSP

Question 8

Flaviviruses: Dengue

Answer 8

-most common arbovirus, Aedes mosquito vector (still water)
Sx – high fever, bone/joint pain, headache, maculopapular rash
Hemorrhagic fever and shock – after previous dengue infection, antibody-dependent enhancement, DEN-2 serotype

Question 9

Flaviviruses: Yellow Fever

Answer 9

West African and S. America → urban (Aedes) and jungle (primates) disease forms
Sx – fever, chills, headache, later bradycardia (Faget’s sign), jaundice, hemorrhage → hypotension

Question 10

Flaviviruses: West Nile

Answer 10

– bird reservoir → mosquito → man
Sx – 80% asymptomatic, 19% fever, 1% meningitis or encephalitis (elderly)
Encephalitis – bite → Langerhans cells infected → LNs → 1° viremia → replication in macros → 2° viremia → CNS glia → T cell recruitment by cytokines → brain inflammation → viral clearance

Question 11

Bunyaviruses:

Answer 11

no man-to-man transmission (dead end host)

Question 12

Bunyaviruses:

Answer 12

Structure – enveloped, ss(-)RNA, G1,2 glycoproteins

Question 13

Hantaviruses (Type of Bunyavirus)

Answer 13

– rodent transmission → striped field mouse, bank vole, deer mouse, rat → aerosol, bites, direct contact
Hantaan, Poorgia – field mice → China, east USSR, south Europe → severe classical type hantaviruses disease
Seoul type – rats → China, Japan, west USSR, USA, S. America → moderate disease
Puumala type – bank voles → Scandinavia, France, UK → mild disease
Sin Nombre – deer mouse → N. America → pulmonary syndrome, high mortality

Question 14

Bunyavirus: Hantaviruses Pathogenesis

Answer 14

– damage to capillaries → vasodilation, congestion, hemorrhage
Febrile – abrupt, flu-like symptoms, rash after 2-3 days
Hypotensive – after day 5, death
Oliguric – day 9, acute renal failure (vessels damage), shock, petechiae, death
Diuretic – day 12-14
Convalescent – 4 months

Question 15

Bunyavirus: Hantavirus Pulmonary Syndrome

Answer 15

Hantavirus Pulmonary syndrome – vessel damage predominantly in the lungs, Sin Nombre virus
Sx – fever, chills, n/v, diarrhea, cough, dyspnea

Question 16

Bunyavirus: Phlebovirus

Answer 16

-Rift Valley Fever – sheep (East Africa) → mosquito (water) → human → human
Sx – flu-like illness, 1% liver necrosis, retinitis, meningioencephalitis,
Tx - Ribavirin
Sandfly fever – rapid onset fever, malaise with complete recovery