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Prions — the infectious, deformed proteins that cause chronic wasting disease in deer — can be taken up by plants such as alfalfa, corn and tomatoes, according to new research from the National Wildlife Health Center in Madison.

The research further demonstrated that stems and leaves from tainted plants were infectious when injected into laboratory mice.

The findings are significant, according to the researchers and other experts, because they reveal a previously unknown potential route of exposure to prions for a Wisconsin deer herd in which the fatal brain illness continues to spread. The disease has also become a pressing issue nationwide: The national Centers for Disease Control and Prevention has identified the deer disease in 17 states and predicts it will spread to other states.

In Wisconsin, where the state Department of Natural Resources has scaled back its efforts to slow the spread of CWD, some critics say the new research should cause the agency to revisit its approach.

Michael Samuel, a CWD researcher and wildlife ecology professor at the University of Wisconsin-Madison who was not involved in the plant research, said the new study is significant. Previous studies have shown the disease can be transmitted animal-to-animal and via soil.

"It's important because it identifies a potential pathway," Samuel said of the study.

Christopher Johnson, who conducted the study, wrote in the abstract: "Our results suggest that prions are taken up by plants and that contaminated plants may represent a previously unrecognized risk of human, domestic species and wildlife exposure to CWD."