BENNINGTON -- For the past four years the state has collected blood samples from deer killed by hunters and tested them for eastern equine encephalitis (EEE), but it's not clear if the practice will continue.

Erica Berl, infectious disease epidemiologist with the Vermont Department of Health, said twice as many samples, approximately 760, were collected this year compared to last. When a hunter shoots a deer, they must have it weighed in at a designated check station. The Health Department had personnel at 22 such stations across the state to take blood samples and hunters were happy to help.

EEE is a rare, mosquito-transmitted virus. No human cases have been reported in 2013, but two horses in Franklin County died of it. It was first found in Vermont in a flock of emus in Rutland County, according to the Health Department.

Berl said the results from this batch will not be available until April or possibly May, but in the past only about 10 percent of the sample group has come back positive for EEE infection.

She said the test looks for antibodies, which organisms produce to fight infections. None of the deer, even those with EEE, were sickened by it, she said. Deer do not make good EEE carriers, it seems, and "EEE season" peaks in September while the hunting season is in November.

Deer are being tested to see if there any pockets or clusters of EEE infection, Berl said. The best way to do this is mosquito surveys, but those are time consuming and expensive. With deer, hunters bring the samples to the state.

So far there do not appear to be any pockets of EEE, at least not as far as the deer tests show. Vermont began testing its deer herd for the disease after Maine started doing so, initially as a way to see if it had come to the state or not. Berl said it was assumed it had, given it showed up in all the states surrounding Vermont and neighboring Quebec.

Berl said the department planned to test the herd for another year, but the results from this round of sampling will have to be examined first.

Contact Keith Whitcomb Jr. at kwhitcomb@benningtonbanner.com or follow him on Twitter @KWhitcombjr.