Lecture 24

Question 1

Togavirus

Answer 1

Alphavirus - arthropod - borne viruses
Rubivirus - rubella only one
Arterivirus - no human patho

Question 2

Flavivirus

Answer 2

Flavivirus - arthropod-borne viruses
Pestivirus - no human patho
Hepacivirus - Hep C and E viruses

Question 3

Togavirus - Alphavirus

Answer 3

Enveloped
positive sense
single stranded RNA
broad host range from many zoonoses

Question 4

Togavirus patho

Answer 4

Large amount of viral RNA blocks cellular mRNA causing decrease in cellular protein synthesis = cell death

Question 5

Togaviruses

Answer 5

vectors include birds, horses, rodents, monkeys and humans

transmission by mosquitos or ticks

Question 6

Togavirus syndromes

Answer 6

Flu-like symptoms and encephalitis

Pt may be asymptomatic

Question 7

Togavirus syndromes

Answer 7

Eastern Equine Encephalitis virus (EEEV) - Worst one, necrosis of brain, spinal cord and high mortality
Western Equine Encephalitis Virus (WEEV) - causes less damage to CNS usually with complete recovery
Venezuelan Equine Encephalitis Virus (VEEV) - mild disease, rarely causes encephalitis

Question 8

Togavirus treatment

Answer 8

no specific treatment other than suportive care
vaccines available for high risk groups EEEV and WEEV
VEEV vaccine available for animals
mosquito control major prevention

Question 9

Flaviviruses

Answer 9

All are serologically related, antibody against one may neutralize others
All are Arboviruses

Question 10

Flaviviruses Patho

Answer 10

Hemorrhagic fever
Same as Alphaviruses
Reservoirs are birds, small mammals, reptiles and amphibians
Mosquito vector

Question 11

Flavivirus Disease

Answer 11

Viral encephalitis

• St Louis Encephalitis
• West Nile Encephalitis
• Japanese Bee Encephalitis

Hemorrhagic fever

• Yellow Fever
• Dengue Fever

Question 12

St. Louis Encephalitis

Answer 12

Symptoms are fever, headache, myalgia
Most common cause of epidemic encephalitis in North America 
Reservoir are wild birds
Transmission - mosquitos 
3-10% mortality

Question 13

West Nile

Answer 13

Symptoms are fever and meningoencephalitis
80% asymptomatic
Most have fever and lymphadenopathy
Reservoir - wild birds
Transmission - animal to person, direct, mosquitos
Leading cause of Arboviral encephalitis in the US

Question 14

Flavivirus Hemorrhagic fever

Answer 14

Yellow fever, Africa, South and Central America

Dengue Fever, World-wide in tropics

Question 15

Yellow Fever

Answer 15

Rapid onset of fever, chills, headache, dizziness, myalgia, nausea, vomiting,bradycardia
Jaundice, renal failure, systemic hemorrhage
Renal failure = 20% mortality

Question 16

Yellow Fever types

Answer 16

Urban - Domestic
- human reservoir

Mosquito - Aedes Aegypti

Jungle (sylvatic)
Wild primates = monkeys
transmission mosquitos

Question 17

Dengue fever

Answer 17

Fever, HA, myalgia, rash, resembles flu measles or rubella

AKA break-bone fever (severe bone and joint pain)

Question 18

Dengue hemorrhagic fever or shock syndrome

Answer 18

hemorrhages 
plasma leakages
hypotension
shock
circulatory failure