Haemorrhagic fever

Question 1

Which 4 virus families are involved with causing haemorrhagic fever? & the common transmission in each

Answer 1

• Arenaviridae (Group V): rodents
• Bunyaviridae (Group V): insect vector (& Human-contact in CCHF)
• Filoviridae (Group V): infected blood or bodily fluid, human-contact
• Flaviviridae (Group IV): Mosquito/insect (arthropod)

Question 2

List 1-5 viruses in Arenaviridae family causing haemorrhagic fever (HF)

Answer 2

• Lassa virus
• Junnin virus (=Argentina HF)
• Machupo virus (=Bolivian HF)
• Guanarito virus (=Venuzuelan HF)
• Sabia virus (=Brazilian HF)

Question 3

List the 3 types of clinical features caused by dengue.

Answer 3

• Most asymptomatic
• Classical dengue fever: 1st infection = fever rash, headache
• Dengue haemorrhagic fever (DHF) or Dengue shock syndrome (DSS): 2nd infection w/ diff serotype = Aby dependent enhancement

Question 4

What is “antibody dependant enhancement”?

Answer 4

@ 1st infection: mostly asymptomatic, may get DF, mild illness = produces neutralising Aby to that serotype
@2nd infection to diff serotype: Aby not nuetralise 2nd serotype, instead bind at low affinity = taken up by marcoph. & spread V around body

Question 5

Give 5 reasons for the increase in spread of dengue.

Answer 5

• Unplanned urbanisation
• lack of mosquito control
• Inc movement of ppl from travelling
• Inc international trade = vector transport
• Changing enviro. = spread vector

Question 6

What is the major issue with dengue vaccines?

Answer 6

• If vaccine only provides long-term protective immunity to one serotype (not others) = risk for severe DEN infection due to diff serotype = no neutralising effect & Aby Dependent Enhancement = severe HF
• Serotypes can change from 1 season to next

Question 7

How is the ChimeriVax-DEN vaccine made?

Answer 7

Genes encoding YFV prM-Env replaced with that of DENV
- prM: pre-M protein on envelope => induces neutralising Aby
- Env: *dominant viral Ag - Aby made against that

Question 8

What were the contributing factors causing the mortality rate in the 2000 Gulran outbreak

Answer 8

• Late reporting of suspected cases
• Due to lack of awareness & knowledge of HF in HCWorkers & public
• Delayed Ix & control measures & Tx measures
• Taliban gov: underdeveloped health sys

Question 9

How was dengue and yellow fever excluded as possible causes of the 2000 Gulran outbreak?

Answer 9

those viruses are not transmitted by human-to-human contact

Question 10

Why is CCHF the most likely cause of the 2000 Gulran outbreak?

Answer 10

bc transmitted by tick bite, contact w/ infected livestock & human-to-human contact

Question 11

List 2 viruses in Filoviridae family causing haemorrhagic fever

Answer 11

• Ebola virus = Ebola HF
• Marburg virus = Marburg HF

Question 12

List 2 viruses in Flaviviridae family causing haemorrhagic fever

Answer 12

• Yellow fever virus = yellow fever
• Dengue virus = dengue HF

Question 13

List 3 viruses in Bunyaviridae family causing haemorrhagic fever

Answer 13

• Rift valley fever virus = rift valley fever
• Hantavirus = Haemorrhagic fever w/ renal syndrome (HFRS)
• Crimean-congo virus = crimean-congo HF (CCHF)

Question 14

4 Advantages of Live-attenuated vaccine (in comparison to inactivated vaccines)

Answer 14

• Require 1-2 innoculations
• Strong & long-lasting protective immunity
• I.Resp. mimics natural infection
• Inexpensive to produce