Flavivirus and Togavirus Flashcards
What is the reservoir of Arbo Viruses?
Animals
What is the vector of arboviruses?
Insects (ticks, mosquitoes)
Where would the Arbovirus replicate?
In the insect vector
Which arbovirus has dsRNA and a double icosahedral capsid?
Colorado Tick Fever (Retroviridae)
Which arbovirus has ss(+)RNA, and icosahedral capsid and envelope?
- Togaviridae and Flaviviridae
Which arbovirus has ss(-)RNA, a helical capsid and an envelope?
Bunyaviridae
Which 4 classes make up the Arboviruses?
- Togaviridae
- Flaviviridae
- Bunyaviridae
- Reoviridae
What are the significant diseases that could occur from Togaviruses and Flaviviruses?
- Encephalitis
- Hemorrhagic Fever
- Fever and Rash
What are the classes of Togaviridae?
- Alphavirus
2. Rubivirus (Rubella)
Which viruses are protease sensitive?
Togaviruses
Describe the initial presentation for Togaviruses
Insect Bite –> multiplies in RE –> Viremia –> fever, chills, vomiting and pain
What is the cause of the encephalitis that results from Togaviruses?
The virus has crossed the BBB and is causing lesions through neuronophagia –> neck rigidity, confusion and convulsions
What are some Togaviruses (Alphaviruses) that cause encephalitis?
- Eastern Equine Encephalitis
- Western Equine Encephalitis
- Venezuelan Equine Encephalitis
Which Alphavirus is most serious?
Eastern Equine Encephalitis
Describe the vaccination approach to EEE
Horse vaccination to reduce the amount of infection in the natural host
Clinical Infections of Western Equine Encephalitis are seen more commonly in which demographic?
Children
Eastern Equine Encephalitis is more severe in which demographic (fatal in 30%)
Elderly
Which viruses are protease resistant?
Flaviviridae
Describe the first stage of infection by Flaviviruses
Infected bite –> replicates in RE –> Viremia –> Fever, chills, malaise and vomiting
What are the Flaviviruses that can cause encephalitis?
- St. Louis
- Japanese
- West Nile
What are the Flavaviruses that can cause hemorrhagic fever or have multiple systems involvement (viscera, endothelium and skin)?
- Yellow Fever Virus
2. Dengue Fever
Which hemorrhagic fever-causing virus could also present as a less severe disease without the hemorrhagic fever?
Dengue Virus
Describe the second stage of infection in Yellow Fever Virus
- Severe Saddle Back (Diphasic) Fever
- Jaundice (liver necrosis)
- Necrosis of Kidney
- Black Vomit (hemorrhages in the stomach that cause RBCs to react with the acid)
Which virus can be caused by one of four serotypes?
Dengue Fever Virus
Where is Dengue Fever seen?
Tropics
What is the presentation of mild Dengue Fever?
- Maculopapular Rash
- pain in joints and muscles
- Ocular Pain
- Saddle Back Fever
What situation of Dengue Fever is more likely to progress to hemorrhagic fever and shock syndrome?
Primary Infection by Serotype (1, 3 or 4) followed by second infection of Serotype 2 that results in Ab-Antigen reaction that activates monocytes –> immunopathology and concomitant hemoconcentration and thrombocytopenia
What is the treatment of hemoconcentration?
Hydration
What are the possible transmission routes for West Nile Virus?
- Insect Vector
- Blood Transfusion
- Organ Transplant
Serology is useful for which virus?
West Nile Virus
Which virus can be immunized for using the 17DD or 17D204 live attenuated virus?
Yellow Fever
