Due to recent flooding and heavy rain in inland NSW, General Practitioners in Western NSW are advised that there is an increased risk of Ross River virus and Barmah Forest virus infections. Consider arbovirus infections in patients with compatible symptoms and reinforce mosquito prevention messages to patients.
Health Protection NSW (part of NSW Health) has provided the following information to GPs to ensure prevention and testing.
- Routine mosquito surveillance has detected a marked increase in total numbers of mosquitoes in inland areas following recent flood events and heavy rains
- Detections of Ross River virus (RRV) and Barmah Forest virus (BFV) in mosquitoes has already occurred, this is earlier than any previous arboviral season. These viruses have been detected in mosquitoes in the Riverina and Central West regions of NSW.
- There is therefore a heightened risk of RRV and BFV infections in the next few months.
- General practitioners are encouraged to reinforce mosquito-bite prevention messages among their patients and to be alert for patients presenting with arbovirus infections, especially if they have visited rural parts of NSW.
Symptomatic RRV and BFV infections typically include a rash (including on the palms), polyarthritis/arthralgia, myalgia, lethargy and low-grade fever. Symptoms typically last for several days although arthralgia, myalgia and lethargy may occasionally persist for months.
- If testing is required this is typically carried out serologically for both RRV and BFV.
- Infection is confirmed by demonstrating an IgG seroconversion in acute (taken at onset) and convalescent (taken 4 weeks later) samples.
- Infection is considered probable if both IgM and IgG are positive in the setting of a clinically-compatible illness, although serological markers may persist for months or years after infection.
To minimise the risk of mosquito bites, patients should be advised to:
- Cover-up with a loose-fitting long sleeved shirt and long pants when outside
- Apply mosquito repellent containing DEET or Picaridin to exposed skin
- Take special care during peak mosquito biting hours, especially around dawn and dusk
- Remove potential mosquito breeding sites from around the home and screen windows and doors
- Take extra precautions when travelling or camping in areas with a higher risk of mosquito-borne diseases.