Ross River Virus

Question 1

What is your opening line for RRV?

Question 2

Is RRV nationally notifiable?

Answer 2

Yes.
Routine (labs only)

Question 3

Which organism causes RRV disease?

Answer 3

RRV (alphavirus)

Question 4

How is RRV transmitted?

Answer 4

Multiple mosquito vectors:
Culex annulirostris (inland) and Ochlerotatus spp (coastal saltwater).

Reservoir in macropods, other marsupials.

Human-mosquito-human transmission in large outbreaks.

Question 5

Which animals are the principal hosts for RRV?

Answer 5

Reservoir in macropods, other marsupials.

Question 6

What are the clinical features of RRV?

Answer 6

• Many asymptomatic.
• Rash (including buccal/palmar)
• Polyarthritis
• Myalgia
• Lethargy
• Low-grade fever
• Cervical LA.

Symptoms can persist for months; rheumatic symptoms for over a year. Immunity lifelong.

Question 7

Which groups are at high risk of RRV infection?

Answer 7

• Live/travel in endemic area
• Outdoor activities near mosquito breeding sites.

Question 8

What is the definition of a confirmed case of RRV?

Answer 8

Isolation / detection / seroconversion)

Question 9

What is the definition of a probable case of RRV?

Answer 9

IgM + IgG unless previous IgG positive ≥3m earlier

Question 10

How is RRV diagnosed?

Answer 10

PCR or serology (acute and convalescent)

VIDRL reference lab

Question 11

What is the incubation period for RRV?

Answer 11

3-21 days
(usually 7-9 days)

Tip: 3 days to 3 weeks

Question 12

What is the infectious period for RRV?

Answer 12

Humans infectious to mosquitoes first few days of illness

Question 13

What is the outbreak definition of RRV?

Answer 13

Observed > Expected - increase in notifications from geographical area within specific time period.

Question 14

What is the definition of a new / emerging area for RRV?

Answer 14

≥ 2 cases from non-endemic area in same mosquito season with no travel history.

Question 15

Epidemiology: where has RRV been detected in Australia?

Answer 15

Most of mainland Australia

Question 16

Epidemiology: where is RRV considered endemic?

Answer 16

Throughout regional Victoria

Question 17

Epidemiology: when to RRV epidemics / outbreaks occur?

Answer 17

Usually sporadic cases/small outbreaks (Jan to May).

Epidemics/outbreaks occur, usually after heavy rains, or high tides that inundate salt marshes or coastal wetlands.

Question 18

How is RRV prevented?

Answer 18

Standard vector-borne disease prevention:
* Mosquito control
* Bite prevention
* No vaccine

Question 19

What resources are available for RRV public health response?

Answer 19

DoH guideline. No SoNG.

Question 20

How are cases of RRV managed?

Answer 20

• Supportive care
• Case interview - DRSVECTA
• Education

Demo, RFs, Sx, Vax (NA), Exp (endemic area, mosquitoes, environment/parklands), Contacts/co-exposed, Travel hx, Animals

Question 21

How are contacts of RRV managed?

Answer 21

Nil.
Co-exposed may require education but no follow-up indicated.

Question 22

What is the environmental management for RRV?

Answer 22

Standard environmental measures to prevent mosquito exposure.

Question 23

What public health actions are required for new / emerging areas?

Answer 23

• Liaise with stakeholders
• Review recent data (mosquito/human)
• Enhanced surveillance
• Mosquito surveys
• Promote mosquito management
• Clinician alert / advisories
• Health alerts
• Health promotion measures

Question 24

What public health measures are required for outbreaks?

Answer 24

• Prevention activities
• Community education
• Surveys - animal reservoirs, vector species
• Identify breeding places + eliminate
• Enhanced vector control measures
• Predictive modelling
• Enhanced human surveillance (test/notify)
• Closing public land to human access if high risk of acquisition
• Consult NAMAC