Dengue

Question 1

What type of virus causes dengue?

Answer 1

Dengue virus (flavivirus)

Four serotypes exist: 1-4.

Question 2

Is dengue nationally notifiable?

Answer 2

Yes - routine, labs + doctors

Question 3

What is the primary vector for dengue transmission?

Answer 3

Aedes aegypti

Aedes albopictus is also a vector.

Question 4

What are the main clinical features of dengue?

Answer 4

Spectrum of illness: Can range from asymptomatic to severe dengue haemorrhagic fever (DHF).

Typical: fever, headache, retro-orbital pain, muscle pain, rash, lethargy

Question 5

What severe condition can dengue lead to?

Answer 5

Dengue haemorrhagic fever (DHF) - thrombocytopaenia, haemorrhage, shock

Question 6

Who is at higher risk of severe disease?

Answer 6

Reinfection with second serotype.

Question 7

What is the incubation period for dengue?

Answer 7

3-14 days
(usually 4-7 days)

Question 8

What is the infectious period?

Answer 8

• Humans can infect mosquitoes for 4-5 days after Sx
• PH responses - 1 day before to 12 days after Sx onset
• Mosquitoes infectious 8-12 days after

Question 9

What is the definition of an outbreak in relation to dengue?

Answer 9

One case in a receptive area.

Question 10

In which regions is dengue endemic?

Answer 10

South East Asia, Pacific, Central/South America.

Question 11

T / F: Most dengue cases in Australia are from returned travellers

Answer 11

True

Question 12

Where have large outbreaks of dengue occurred in Australia?

Answer 12

QLD - > 40 OBs since 1990 including one with 1000+ cases

Question 13

What preventive measures are recommended for dengue?

Answer 13

• Usual mosquito prevention activities
• Education to travelers - bite avoidance
• Vector surveillance and control

Vaccines are in development.

Question 14

Where does vector monitoring and control occur?

Answer 14

International airports and in receptive areas

Question 15

What resources are available for PH management of dengue?

Answer 15

• SoNG
• DH protocol
• NAMAC - Framework for the surveillance, prevention and control of dengue virus infection in Australia (CDNA)
• QLD dengue management plan

Question 16

What types of laboratory tests are used for dengue diagnosis?

Answer 16

Serology, PCR, NS1 antigen.

Question 17

What is the significance of the NS1 antigen in dengue testing?

Answer 17

NS1 is specific for dengue (vs other flaviviruses).

Question 18

What should be done for a confirmed dengue case?

Answer 18

• Interview - exposure assessment: travel, mosquito bites
• T - Supportive treatment
• I - NA
• E - Sx, transmission, bite prevention

Confirm symptoms and lab results.

Question 19

What actions should be taken if a case is in a receptive area?

Answer 19

• Avoid mosquito bites
• Identify outbreak management measures

Question 20

What is a dengue “receptive area”?

Answer 20

• Residential areas where vector present with transmission in the past 20yrs OR
• Entomologists / PHUs consider risk of transmission

Question 21

How are contacts / co-exposed managed?

Answer 21

• Only needed if case in receptive area
• Co-exposed e.g. HH member, travelled with case, workpace

T - NA
I - NA
E - sx, testing, transmission, prevention

Question 22

How are dengue outbreaks managed?

Answer 22

Plans: Follow NAMAC FW and QLD Dengue Mgmt Plan
Team: IMT needed

Actions:
* Urgent determination of risk of further transmission - vector surveys, weather
* SHs: council, entomologist, EHO, Ag, health promotion, comms, labs, GP, ID
* Alerts - clinicians for active case finding; media; schools/RACFs/prisons
* Enhanced mosquito surveillance and control - traps, spraying, ovitraps
* Community-level mosquito reduction - collab with industry / public

Question 23

What is the role of entomologists in dengue outbreak management?

Answer 23

Review recent vector surveys and assess risk of further transmission.

Question 24

What is the purpose of community-level mosquito reduction?

Answer 24

To collaborate with industry and public to reduce mosquito populations.

Question 25

True or False: Humans can transmit dengue to mosquitoes before showing symptoms.

Answer 25

True.

Question 26

What should be done if the case has no travel hx, not in a receptive area, and vectors are present?

Answer 26

Notify CHO, NAMAC, NIC, WHO. Response per NAMAC framework.