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Barmah Forest virus

Revision History

Version Date Changes
1.0 January 2017  Full revision

Infectious Agent

The infectious agent is the Barmah Forest virus, an alphavirus.

Notification Criteria

Clinical Evidence
Not required

Laboratory definitive evidence

Isolation of Barmah Forest virus


Detection of Barmah Forest virus by nucleic acid testing


IgG seroconversion or a significant increase in IgG antibody levels (e.g. fourfold or greater rise in titre) to Barmah Forest virus.

Laboratory suggestive evidence

Detection of Barmah Forest virus IgM AND Barmah Forest IgG EXCEPT if Barmah Forest IgG is known to have been detected in a specimen collected greater than 3 months earlier.

Community Outbreak Criteria

Not applicable

Notification Procedure  

Pathology Laboratories

Notify all confirmed and probable cases of Barmah Forest virus by facsimile, email or other electronic means.

Reporting to NOCS

Report confirmed and probable cases.

Confirmed case

A confirmed case requires laboratory definitive evidence only.

Probable case

A probable case requires laboratory suggestive evidence only.

Public Health Significance and Occurrence       

Barmah Forest virus is found only in Australia and causes outbreaks of polyarthritis in humans. The disease is very similar to that caused by infection with Ross River virus.  Barmah Forest virus has been detected in most parts of mainland Australia and serological surveys indicate that it causes widespread human infection.

Clinical Features

A self-limiting, febrile illness, similar to Ross River virus infection, with arthralgia/arthritis, myalgia, lethargy and rash. All people who develop the disease do recover. It is not fatal.  There is a high subclinical rate of illness and low disease rate in children. Recovery usually occurs within several weeks, but symptoms may persist for over six months.


Probably mammals; BFV antibodies have been found in kangaroos, cattle, horses and sheep on the south coast of New South Wales.

Mode of Transmission      

Via mosquito vectors especially Culex annulirostris in inland areas, while Ochlerotatus (previously Aedes) vigilax, Aedes (Verrallina) funereus and Ochlerotatus camptorhynchus are the major vectors in coastal regions. Vectors usually bite between dusk and dawn. The breeding sites, preferred feeding time and dispersion distances vary depending on the vector.

Incubation Period 

Usually 3-11 days.

Period of Communicability

No evidence of human to human transmission.

Susceptibility and Resistance

Recovery is universal with lasting immunity; Second attacks are unknown.  Inapparent infections are common especially in children.



Public health investigation of individual cases is not warranted.


Contact tracing


Community outbreaks/epidemics

  • Identify species involved and their breeding places and promote control
    Promote mosquito avoidance at biting times. Advise the use of personal protective measures (long sleeved clothes, mosquito repellents and mosquito coils).
  • Other control measures

    Airport vector control may be necessary to prevent international transmission.

Preventive measures

  • Mosquito control measures – depends on which vectors are involved.
  • Personal protection measures – long sleeved clothes, mosquito repellents and mosquito coils)
  • Avoidance of mosquito-prone areas.
  • Notification is usually not timely. Therefore surveillance and control of mosquitoes rather than surveillance of cases is a preferable public health measure.
  • Feedback            


Report to notifying agency.


Prepare a report of the investigation for the Communicable Diseases Branch, Queensland Health.


Communicable Diseases Network Australia, Barmah Forest Virus case definition 2016:

Heymann, D. (Ed).  2015. Control of Communicable Diseases Manual, 20th edition.  American Public Health Association: Washington.

Queensland Health, Barmah Forest Virus Fact Sheet:

Last updated: 13 February 2017