By Lucy Carroll and Liam Mannix
Multiple cases of Japanese encephalitis have been detected across Australia’s east coast, with one woman now in hospital on life support, prompting the federal health department to declare an incident of national significance.
On Friday afternoon, Victorian health authorities said the number of suspected cases had doubled to eight from Wednesday, including two children, and that six people were in hospital with the virus.
The cases come after authorities discovered a massive outbreak at pig farms in NSW, Queensland and Victoria that had gone undetected for weeks.
Queensland authorities on Friday confirmed a woman in her 60s was in Prince Charles Hospital in a critical condition after contracting the disease while on a campervan trip. Federal authorities are investigating several other cases of encephalitis of unknown origin.
NSW Health also confirmed it had one “highly probable” case on the NSW-Victoria border region in ICU in a stable condition.
In Victoria, the eight suspected cases are in two children under 10 and six adults aged between 35 and 75.
Outbreaks have now been confirmed at 14 piggeries across NSW, South Australia, Queensland and Victoria, up from nine on Wednesday. The emergence of the virus, never before been seen south of Cape York, has taken scientists and health authorities by surprise as they scramble to deal with the emergence of new cases.
In a statement on Friday afternoon, Australia’s Acting Chief Medical Officer Dr Sonya Bennett said the unfolding situation concerning Japanese encephalitis was a communicable disease incident of national significance.
“A national approach is required in relation to coordination of health policy, interventions and public messaging,” Dr Bennett said.
“The Department of Health is aware of other cases, in multiple states, of encephalitis of unknown origin that are being investigated for arboviral diseases, including Japanese encephalitis.”
A declaration was made under the emergency response plan consultation with the Australian Health Protection Principal Committee.
“A national working group of communicable disease, vaccine and arbovirus experts has been established to support the response, including mosquito surveillance and control measures and identification of those at direct risk and for the rollout of vaccines,” Dr Bennett said.
Japanese encephalitis virus is a mosquito-borne disease related to dengue and yellow fever.
It is generally harmless but in the fewer than 1 per cent of cases where symptoms do develop, one in three will die.
The viral disease mostly occurs in pigs and horses, but can cause disease in people and rarely other animals.
“Pigs are the focus from a human health perspective as they can infect mosquitoes that can then infect humans,” a statement from Dr Bennett said. The virus cannot be transmitted between humans, and cannot be caught by eating pork or pig products.
Globally, the mosquito-borne virus, which spreads between waterbirds, pigs and humans, kills about 17,000 people a year, but it has never been seen south of Cape York. Experts say the deadly disease was brought here by the warming climate and is now here to stay.
A spokesperson for federal health department said two different vaccines are available for protection against the virus in Australia and supplies for a targeted vaccination program is available for areas hit by the virus.
“The Commonwealth and the states and territories can access additional vaccines should the requirements expand,” a spokesperson said.
“It’s important to reiterate the importance of relatively simple mosquito bite prevention measures – and messages have been disseminated to outline these. Japanese encephalitis infections can be contracted by humans through the bite of a mosquito. It is not then transmitted from human to human.”
“Pigs are the focus from a human health perspective as they can infect mosquitoes who then infect humans. This is not the case with horses. Mosquitos who bite an infected human can’t then pass it on to another human,” a spokesperson said.
“There is a range of work in the jurisdictions to ramp up control around affected piggeries and undertake mosquito surveillance as the first line of defence.”
Professor Peter Collignon, an infectious diseases expert at the Australian National University, said for those that are infected the majority have mild disease.
“At the moment we are looking for anyone in hospitals who has encephalitis or meningitis where the cause isn’t clear,” he said. “Basically, all hospitals are on alert looking out for it and sending appropriate blood test and cerebrospinal fluid samples to be checked for the disease.”
“We do need to know how widespread it is and who is catching it. It is mainly a concern for pig the industry and the closer you are to the infection source the more aware you need to be.”
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