Barmah Forest Virus (BFV), a "sister" arbovirus to Ross River Virus (RRV), was discovered in 1974. Both BFV and RRV are found throughout Australia and the two main causes of Epidemic Polyarthritis. Though RRV has also been responsible for outbreaks in various other areas of Oceania (Eastern Indonesia, Papua New Guinea and certain Pacific Islands), BFV has remained more confined. The transmission vectors are a variety of mosquito species (primary) and other insects that feed on blood. Though kangaroos and wallabies are the known primary mammal hosts for RRV, little is known about the hosts for BFV.
BFV is a non-fatal disease which mimics the symptoms associated with influenza or rubella (measles) in more severe cases. Recently, BFV and RRV infections have been rising in the rural areas of Western Australia. BFV can not be transmitted through human to human contact.
- When outdoors, use insect repellent containing 35% DEET for adults and 10% DEET for children. Follow the directions on the package.
- Many mosquitoes are most active at dusk and dawn. Be sure to use insect repellent and wear long sleeves and pants at these times or consider staying indoors during these hours.
- Avoid wearing dark coloured clothing.
- Avoid wearing perfume/cologne and scented cosmetics.
NO pre or post-exposure vaccines are available.
Symptoms and Treatment
Statistics and symptom manifestations of Barmah Forest Virus are identical to RRV because the viruses are so closely related ("sister" viruses).
- Statistics have shown that 70-90% of those infected with BFV will not develop any symptoms of the disease during the course of the illness and symptoms in infected children are virtually unseen.
- The remaining 10-30% of infected patients will manifest symptoms that can vary widely. The onset time is 3-21 days with the average symptom onset at 7-9 days.
- Mild symptoms of BFV will mimic those of influenza: lethargy, headache, mild weakness, joint pain, possible low-grade fever (if any), and loss loss of appetite. Recovery occurs in these patients within a few days.
- Moderate symptoms of BFV can mimic those of rubella (measles) and/or varicella (chicken pox): lethargy, headache, joint pain, high fever, loss of appetite, and nausea. A rash developing on the torso and limbs, which may be the first presenting symptom. Because the rash presents itself similarly to those seen with rubella and varicella, it is the main cause of BFV being misdiagnosed. Recovery in these patients can take up to eight weeks though the average recovery time is closer to 14 days in duration.
- Severe symptoms of BFV can be a combination of those seen in moderate manifestations but will also include more localized and intense ligament/tendon/joint pain and swelling of joints (mainly those of the limbs, though the jaw can also be involved). These rheumatic symptoms can present themselves gradually or "explosively". Some patients may experience swelling of the spleen (splenomegaly), spinal chord (meningitis) and/or brain (encephalitis). Some may also develop blood in the urine (haematuria). Recovery time for these patients can take 6-12 months though most recover more quickly with proper diagnosis and treatment.
- BFV can only be accurately diagnosed through laboratory analysis of a patient's blood sample. Additional blood analyses may be performed to rule out other diseases and/or conditions, such as rheumatoid arthritis factor, rubella, varicella, Ross River Virus, and Q fever.
At this time there are no specific treatments for BFV. Those requiring medical attention will be treated symptomatically. Those with rheumatic symptoms will be treated with NSAIDS (non-steroidal anti-inflammatory drugs) or other medications designed for rheumatoid-type conditions.