The disease was then found in all Australian mainland states and the Northern Territory.
Since January 1, 2021, seven people in Australia have died because of it.
MPI has told RNZ that the risk of the JEV establishing in New Zealand was low, but could increase in the next 15-20 years, due to climate change.
The ministry is now conducting research to identify the highest risk locations in New Zealand for the establishment of the disease, so it can target ongoing surveillance.
Epidemiologist Professor Roger Morris wrote a paper on the risk of the virus to New Zealand in 2023 and told RNZ he had been encouraging MPI to do this work.
Morris said if the virus got into New Zealand, it would be good to detect it quickly.
“The main concern with this is the potential for human cases to occur in New Zealand as they did very suddenly in Australia.”
He said the disease would most likely make its way to New Zealand through mosquito larvae on boats or waterbirds that travel across the Tasman.
Morris told RNZ he was quite concerned about the risk that climate change posed in relation to the disease.
“We already have a mosquito in New Zealand that is quite capable of transmitting this virus, but it will transmit more effectively if temperatures go up.
“There are a number of other diseases that are spread by mosquitoes that will become more likely if temperatures go up, but we’re particularly concerned by Japanese encephalitis because of the ease with which it spreads.”
MPI’s research into JEV is set to start over the coming year with findings published by 2028 - the timeframe is impacted by the seasonal work needed to trap mosquitoes.
The ministry also tests for JEV as part of its annual arbovirus surveillance. It tests cattle blood samples annually from 128 farms - all of which have been negative.
Last year 100 dog blood samples were also tested to help validate MPI’s tests, which were also all negative.
- RNZ
