Fact sheets
Arborviral (Murray valley) encephalitis fact sheet (PDF 223KB)
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Notifiable disease data and reports
Additional sources of information
Case definition
MVE
Confirmed case
A confirmed case requires laboratory definitive evidence AND clinical evidence.
Laboratory definitive evidence
1. Isolation of Murray Valley encephalitis virus
OR
2. Detection of Murray Valley encephalitis virus by nucleic acid testing
OR
3. IgG seroconversion or a significant increase in antibody level or a fourfold or greater rise in titre to Murray Valley encephalitis virus
OR
4. Detection of Murray Valley encephalitis virus-specific IgM in cerebrospinal fluid in the absence of IgM to Kunjin, Japanese encephalitis or dengue viruses
OR
5. Detection of Murray Valley encephalitis virus-specific IgM in serum in the absence of IgM to Kunjin, Japanese encephalitis or dengue viruses. This is only accepted as laboratory evidence for encephalitic illnesses.
Confirmation of laboratory result by a second arbovirus reference laboratory is required if the case occurs in areas of Australia not known to have established enzootic/endemic activity or regular epidemic activity.
Clinical evidence
1. Non-encephalitic disease: acute febrile illness with headache, myalgia and/or rash
OR
2. Encephalitic disease: acute febrile meningoencephalitis characterised by one or more of the following:
- focal neurological disease or clearly impaired level of consciousness
- an abnormal computerised tomograph or magnetic resonance image or electrocardiograph
- presence of pleocytosis in cerebrospinal fluid
OR
3. Asymptomatic disease: case detected as part of a serosurvey should not be notified.
Kunjin
A confirmed case requires laboratory definitive evidence AND clinical evidence.
Laboratory definitive evidence
1. Isolation of Kunjin virus
OR
2. Detection of Kunjin virus by nucleic acid testing
OR
3. IgG seroconversion or a significant increase in antibody level or a fourfold or greater rise in titre to Kunjin virus
OR
4. Detection of Kunjin virus-specific IgM in cerebrospinal fluid
OR
5. Detection of Kunjin virus-specific IgM in serum in the absence of IgM to Murray Valley
encephalitis, Japanese encephalitis or dengue viruses. This is only accepted as laboratory evidence for encephalitic illnesses.
Confirmation of laboratory result by a second arbovirus reference laboratory is required if the case occurs in areas of Australia not known to have established enzootic/endemic activity or regular epidemic activity.
Clinical evidence
1. Non-encephalitic disease: acute febrile illness with headache, myalgia and/or rash
OR
2. Encephalitic disease: acute febrile meningoencephalitis characterised by one or more of the following:
- focal neurological disease or clearly impaired level of consciousness
- an abnormal computerised tomograph or magnetic resonance image or electrocardiograph presence of pleocytosis in cerebrospinal fluid
OR
3. Asymptomatic disease: case detected as part of a serosurvey should not be notified.
Japanese Encephalitis
Confirmed case
A confirmed case requires laboratory definitive evidence AND clinical evidence.
Laboratory definitive evidence
1. Isolation of Japanese encephalitis virus
OR
2. Detection of Japanese encephalitis virus by nucleic acid testing
OR
3. IgG seroconversion or a significant increase in antibody level or a fourfold or greater rise in titre of Japanese encephalitis virus-specific IgG proven by neutralisation or another specific test, with no history of recent Japanese encephalitis or yellow fever vaccination
OR
4. Detection of Japanese encephalitis virus-specific IgM in cerebrospinal fluid, in the absence of IgM to Murray Valley encephalitis, Kunjin and dengue viruses
OR
5. Detection of Japanese encephalitis virus-specific IgM in serum in the absence of IgM to Murray Valley encephalitis, Kunjin and dengue viruses, with no history of recent Japanese encephalitis or yellow fever vaccination.
Confirmation of laboratory result by a second arbovirus reference laboratory is required if the case appears to have been acquired in Australia.
Clinical evidence
A clinically compatible febrile illness of variable severity associated with neurological symptoms ranging from headache to meningitis or encephalitis. Symptoms may include headache, fever, meningeal signs, stupor, disorientation, coma, tremors, generalised paresis, hypertonia, and loss of coordination. The encephalitis cannot be distinguished clinically from other central nervous system infections.
