These are also the first known locally-acquired detections of JE in humans in these states of Australia and the first detections in mainland Australia since a single case was detected in 1998 in Cape York, Queensland.
Australia experienced an outbreak of JEV in domestic pigs in 2022, with detections in over 80 piggeries in Queensland, New South Wales, Victoria and South Australia. Prior to this, JEV was thought to be limited to seasonal transmission in the Torres Strait Islands and (occasionally) Far North Queensland.
This is the first case of Japanese encephalitis to be diagnosed on the Australian mainland. In 1995 three cases, including two deaths, were reported in the outer Torres Strait islands. A further case was reported in the Torres Strait in March 1998.
About Japanese encephalitis
It is spread through bites from mosquitos, which become infected through biting infected pigs and waterbirds. JEV is endemic to parts of Asia and the Torres Strait region of Australia. JEV has now also been detected in humans, animals and mosquitos in mainland Australia.
The first case of Japanese encephalitis viral disease (JE) was documented in 1871 in Japan. The annual incidence of clinical disease varies both across and within endemic countries, ranging from <1 to >10 per 100 000 population or higher during outbreaks.
These results suggest that JEV originated from its ancestral virus in the Indonesia-Malaysia region and evolved there into the different genotypes which then spread across Asia.
As of February 2023, 46 human cases of JEV and seven deaths have been reported for this outbreak (Supplementary Table 1).
There have been seven deaths from 45 cases of JE notified in Australia since January 1, 2021, with almost all of the cases from 2022.
How common is Japanese encephalitis? It's very rare for travellers visiting risk areas to be affected by Japanese encephalitis. It's estimated less than 1 in a million travellers get Japanese encephalitis in any given year.
Two in New South Wales, two in South Australia, one in Victoria, one in Queensland and one in the Northern Territory.
Japanese encephalitis is found mostly in Asia - from India in the west to North and South Korea, and Japan in the northeast. It is also found from Thailand, Singapore, and Malaysia in the south, to Indonesia, Timor, and Papua New Guinea in the southeast.
Booster doses
For those at risk of JEV infection (as advised by your local public health authority) who are previously vaccinated with a JEV vaccine, a booster dose is recommended if more than 1 year has passed since the last primary course dose.
JE is a seasonally endemic and is notifiable because it can transfer to humans, not because of a significant threat to pig populations. Disease occurs most commonly in pigs and horses. Few species are thought to play a significant role in the natural transmission of JEV – most commonly waterbirds and pigs.
Most people infected with JE do not have symptoms or have only mild symptoms. However, a small percentage of infected people develop inflammation of the brain (encephalitis), with symptoms including sudden onset of headache, high fever, disorientation, coma, tremors and convulsions. About 1 in 4 cases are fatal.
There are no treatments for JE and the case fatality rate among symptomatic cases can be as high as 30%. Permanent neurologic or psychiatric sequelae can occur in 30–50% of cases with encephalitis.
It takes 5 to 15 days after the bite of an infected mosquito to develop symptoms.
Japanese encephalitis vaccination. The vaccine gives protection for more than 9 out of every 10 people who have it. You should get vaccinated if you're: planning a long stay in a high-risk country (usually at least a month)
A booster dose (third dose) should be given if a person has received the two-dose primary vaccination series one year or more previously and there is a continued risk for JE virus infection or potential for reexposure. For adults and children aged 3 years or older, each dose of IXIARO is 0.5 mL.
Who has a higher chance of getting the Japanese encephalitis virus? Those who are more likely to get Japanese encephalitis virus are: people who work or do outside activities (e.g., camping, fishing, hiking, gardening) in high-risk areas.
Every year in the United States: Nearly 200,000 women are diagnosed with a cervical precancer. 11,100 women are diagnosed with cervical cancer caused by HPV. About 4,000 women die from cervical cancer.
As with treatment, autoimmune encephalitis recovery depends mainly on the specific clinical case, the form of encephalitis, and the after-effects of the disease. However, the autoimmune encephalitis life expectancy after encephalitis, in general, ranges from 60 to 90 years in different countries.
Japanese encephalitis (JE) virus, a flavivirus, is closely related to West Nile and St. Louis encephalitis viruses. JE virus is transmitted to humans through the bite of infected Culex species mosquitoes, particularly Culex tritaeniorhynchus.
Mode of transmission of Japanese encephalitis virus
JE virus is transmitted to humans through the bite of an infected mosquito, primarily the Culex species. People cannot be infected by eating meat. Pork or pork products are safe to consume.
There are two safe and effective JEV vaccines: Imojev : one dose vaccine available for use in people aged 9 months and older. JEspect / Ixiaro: two doses for use in infants and children aged ≥2 months and older, including people who are immunocompromised, and pregnant women.
A case-‐control study of licensed vaccine found two doses to be 98% effective.