At least a dozen confirmed or probable cases of JE were reported in Victoria over summer, with most having been exposed to the disease carried by mosquitos in northern and north-western Victoria or southern NSW.
From early November to early April, there were also 138 cases of Ross River Virus.
In response, the department said it increased mosquito surveillance, trapping and control measures, and in a statement in mid-April, also issued a warning that people should remain vigilant through the autumn months.
“There have been high numbers of mosquitos over the recent summer months, and while we’ve had a change in seasons, mosquitos are still active at this time of year and can carry dangerous diseases such as Japanese encephalitis and Ross River virus,” a spokesperson said.
The department added that “enhanced mosquito surveillance, trapping and control measures continue to be undertaken, including near affected pig farms and in other areas of northern Victoria along the Murray River, to continuously monitor whether JE virus is still present”.
The departmental statement pointed to that surveillance resulting in the trapping of mosquitos that were carrying JE.
“Some mosquitos trapped in northern Victoria have returned positive results for JE virus, with control measures increased where potential exposure sites are identified and where mosquito numbers have increased,” the statement said.
Despite repeated requests from the News, however, the department has not revealed where the discoveries were made, what control measures were used or to what degree the mosquito numbers had increased by.
JE virus can cause a rare, but potentially serious, infection of the brain.
Most people infected experience no or very mild symptoms and fully recover, but some develop a sudden onset of fever, headache, vomiting and seizures or disorientation, in which case they should seek urgent medical attention.
Anyone at risk of being bitten by mosquitos is advised to wear long and loose-fitting clothing and to use effective mosquito repellents containing picaridin or DEET to prevent themselves being bitten.
