Lecture 31 - Dengue Flashcards
What are the different types of DENV?
What is important about these types?
DENV-1
DENV-2
DENV-3
DENV-4
Antigenetically cross reactive
What sort of infection does DENV cause?
Acute, systemic
- clinically mild
May be asymptomatic
How is Dengue transmitted?
Mosquito vector
Aedes aegypti
If an individual has been infected with one type of dengue, what can we say about infection in the future?
Same type: lifelong immunity
Different type: enhanced risk of more serious disease
What are our treatment and prevention options for Dengue?
No antivirals
No vaccine
Which group is most susceptible to infection in endemic countries
Paediatric population commonly affected
What is the infectious period ?
4-6 days
What are the incubation periods?
Extrinsic: incubation in the mosquito
Intrinsic: time from mosquito bite until clinical manifestations are seen.
What are the common symptoms of Dengue infection?
Fever Headache Myalgia Fatigue Vomiting Anorexia Joint pain
What is happening in severe dengue?
Severe plasma leakage
Haemorrhage
Organ impairment
‘Dengue shock syndrome’
To which countries is Dengue endemic?
South East Asia
India
Central Africa
South America
Why is Dengue a new virus?
Urbanisation
Human movement
How many cases of Dengue per year?
100 million symptomatic
2.1 severe cases
Describe the epidemiology of Dengue in southern Vietnam
Heterogeneous
Differs year to year
- location
- incidence
What type of virus is Dengue?
Flavivirus
What are some Flaviviruses?
Yellow fever
Japanese encephalitis
West Nile virus
Describe the structure of Dengue virus
Envelope RNA genome Three structural proteins: - E - C - M
What are Dengue genotypes
Named about where they have been genotyped
Multiple genotypes per type eg. DENV-1
What is the DENV proteome?
Sequence of all the proteins that this virus makes
Allows us to rationally develop drugs that target these proteins
Describe the activity of Aedes aegypti
Lays eggs in artificial containers
Rest on surfac inside homes
Daytime biting of humans
–> mosquito infected for life
How are dengue Mosquitos controlled?
Chemical vector control - no evidence that this works Education Vaccine development Wolbachia introduction into Aedes agypti
What is the most developed vaccine in trials?
Live attenuated
Envelope proteins
Tetravalent
In phase III
Phase II results:
- 30% efficacy
What is Wolbachia?
Intracellular bacterium
Found in 80% of insects worldwide
Change reproductive behaviour of the mosquitoes that they live in
–> reproductive advantage for Wolbachia infected mosquitoes
Shortens life span of mosquito
Why would Wolbachia be introduced into Aedes aegypti ?
The infected mosquitoes will haves shorter life span (10 days shorter)
Reduced likelyhood of transmission of dengue virus
What was the result of Wolbachia infection?
Shorter life span
Mosquitoes are resistant to Dengue infection
–> due to competition between Dengue and Wolbachia
What are the different Wolbachia strains?
wMel
- fit
- intermediate ability to block dengue virus replication
wMel Pop
- unfit in the field
Describe the Yorkeys Knob field trial
After release in 2011, there was an increase in Wolbachia infected Aedes Agypti
Describe the intentions of the Pilot field release
- determine if wMelPop is sustainable
- best way of release
- effects on viral interference
Describe the results of the Vietnam field trial
So far, increase in percentage of Mosquitoes with Wolbachia
