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Annual report National Notifiable Diseases Surveillance System, 2004
Japanese encephalitis virus
Case defi nition – Japanese encephalitis
virus
Only confirmed cases are reported.
Confirmed case: Requires isolation of
Japanese encephalitis virus, OR detection of
Japanese encephalitis virus by nucleic acid
testing, OR IgG seroconversion or a signifi cant
increase in antibody level or a fourfold or
greater rise in titre of Japanese encephalitis
virus-specifi c IgG proven by neutralisation or
another specifi c test, with no history of recent
Japanese encephalitis or yellow fever vaccination,
OR detection of Japanese encephalitis
virus-specifi c IgM in cerebrospinal fl uid, in the
absence of IgM to Murray Valley encephalitis,
Kunjin and dengue viruses, OR detection of
Japanese encephalitis virus-specifi c 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.
AND 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.
Confi rmation of laboratory result by a second
arbovirus reference laboratory is required if
the case appears to have been acquired in
Australia.
There was one case of Japanese encephalitis virus
(JEV) notifi ed in February 2004, when Queensland
reported that a 66-year-old male acquired JEV
from Papua New Guinea. There have been nine
other cases of JEV reported to NNDSS since 1995,
although JEV was not nationally notifi able until
2001. Four of these nine notifi cations were reported
in Torres Strait Islanders from the Badu Island community.
The other locally acquired JEV case was
reported in a resident from the Cape York Peninsula,
Queensland. The remaining four cases were
reported as acquired from overseas countries.
The Australian Quarantine and Inspection Service,
through the Northern Australia Quarantine Strategy
(NAQS) program, conducted monitoring for JEV for
the 2004 wet season using sentinel pigs at sites
on Badu Island in Torres Strait and its northern
peninsula area (NPA) site at Injinoo airport in Cape
York Peninsula. The fi ve sentinel pigs on Badu
Island all seroconverted (based on results of testing
at Queensland Health Scientifi c Services and the
CSIRO Australian Animal Health Laboratory). JEV
was also identifi ed through the detection of RNA by
TaqMan polymerase chain reaction in a pool of culicine
mosquitoes collected in a Banks trap on Badu
Island. This was collaborative mosquito trapping
performed by NAQS for Queensland Health.
The fi ve NPA sentinel pigs located at Injinoo Airport,
all seroconverted to JEV (based on results of testing
at Queensland Health Scientifi c Services and the
CSIRO Australian Animal Health Laboratory). This is
the second time that JEV has been detected on the
mainland; the fi rst detection was in 1998. As a follow
up to this mainland detection, the Queensland Health
Tropical Public Health Unit conducted mosquito trapping
at various sites in the NPA. A total of 147 pools,
comprising 23,144 mosquitoes, were processed
using the JEV-specifi c TaqMan RT-PCR. Pools were
comprised of up to 200 mosquitoes. There was one
positive pool of 200 mosquitoes obtained from a trap
set at Bamaga rubbish tip. There was inconclusive
serological evidence of exposure to JEV in feral pigs
sampled by NAQS on the west coast of Cape York
Peninsula in July 2004. The time of exposure could
not be determined, but it is unlikely to be linked to
the 1998 incursion.
60 CDI Vol 30 No 1 2006