Dengue

Question 1

What is geographical spread of dengue?

Answer 1

SA
Africa
Asia

Question 2

What is vector for dengue?

Answer 2

Aedes egypti

Question 3

What is life cycle of dengue?

Answer 3

Aedes aegypti has life cycle in humans and monkeys (jungle dengue)

Virus replicates in dendritic cells/ monocytes/ liver/ spleen

Question 4

What is incubation period?

Answer 4

4-8 days

Question 5

What are dengue symptoms?

Answer 5

Nausea
vomiting
fever
headache
rash - erythematous/ maculopapular

Question 6

Following repeated dengue infection, dengue haemorrhagic syndrome can occur

What is pathogenesis of this?

Answer 6

Antibody mediated enhancement

Primary infection produces antibodies to dengue serovar

Secondary infection with different serovar causes enhanced antibody response. This actually enables it to infect monocytes more easily. Combined with production of cytokines, this causes shock

mortality 10%

Question 7

What is treatment of dengue?

How to prevent dengue?

Answer 7

Supportive - may need blood products

Dengue vaccine - tetravalent. Only recommended for high endemic areas (not travellers), as risk of dengue haemorrhagic syndrome (DHS)

Question 8

Which Dengue vaccines exist?

What viral backbones are used for the vaccine?

Answer 8

DengVaxia - Yellow fever backbone

DenVax - Dengue virus backbone

Both live attenuated vaccines

Question 9

Dengue vaccines

All vaccines are tetravalent vaccines

What is their efficacy?

Answer 9

DengVaxia + DenVax - both approximately 30-60% protective

Can only be given to people who have had infection previously. So not useful for UK travelling abroad. Unless they get baseline dengue serology done beforehand, which is positive