Lecture 31 - Dengue Flashcards Preview

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Flashcards in Lecture 31 - Dengue Deck (29):
0

What sort of infection does DENV cause?

Acute, systemic
- clinically mild

May be asymptomatic

1

What are the different types of DENV?
What is important about these types?

DENV-1
DENV-2
DENV-3
DENV-4

Antigenetically cross reactive

2

How is Dengue transmitted?

Mosquito vector

Aedes aegypti

3

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

4

What are our treatment and prevention options for Dengue?

No antivirals
No vaccine

5

Which group is most susceptible to infection in endemic countries

Paediatric population commonly affected

6

What is the infectious period ?

4-6 days

7

What are the incubation periods?

Extrinsic: incubation in the mosquito

Intrinsic: time from mosquito bite until clinical manifestations are seen.

8

What are the common symptoms of Dengue infection?

Fever
Headache
Myalgia
Fatigue
Vomiting
Anorexia
Joint pain

9

What is happening in severe dengue?

Severe plasma leakage
Haemorrhage
Organ impairment

'Dengue shock syndrome'

10

To which countries is Dengue endemic?

South East Asia
India
Central Africa
South America

11

Why is Dengue a new virus?

Urbanisation
Human movement

12

How many cases of Dengue per year?

100 million symptomatic

2.1 severe cases

13

Describe the epidemiology of Dengue in southern Vietnam

Heterogeneous

Differs year to year
- location
- incidence

14

What type of virus is Dengue?

Flavivirus

15

What are some Flaviviruses?

Yellow fever
Japanese encephalitis
West Nile virus

16

Describe the structure of Dengue virus

Envelope
RNA genome
Three structural proteins:
- E
- C
- M

17

What are Dengue genotypes

Named about where they have been genotyped

Multiple genotypes per type eg. DENV-1

18

What is the DENV proteome?

Sequence of all the proteins that this virus makes

Allows us to rationally develop drugs that target these proteins

19

Describe the activity of Aedes aegypti

Lays eggs in artificial containers
Rest on surfac inside homes
Daytime biting of humans
--> mosquito infected for life

20

How are dengue Mosquitos controlled?

Chemical vector control
- no evidence that this works
Education
Vaccine development
Wolbachia introduction into Aedes agypti

21

What is the most developed vaccine in trials?

Live attenuated
Envelope proteins
Tetravalent
In phase III

Phase II results:
- 30% efficacy

22

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

23

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

24

What was the result of Wolbachia infection?

Shorter life span

Mosquitoes are resistant to Dengue infection
--> due to competition between Dengue and Wolbachia

25

What are the different Wolbachia strains?

wMel
- fit
- intermediate ability to block dengue virus replication

wMel Pop
- unfit in the field

26

Describe the Yorkeys Knob field trial

After release in 2011, there was an increase in Wolbachia infected Aedes Agypti

27

Describe the intentions of the Pilot field release

- determine if wMelPop is sustainable
- best way of release
- effects on viral interference

28

Describe the results of the Vietnam field trial

So far, increase in percentage of Mosquitoes with Wolbachia