MADISON, Wis. — Scientists have discovered that ruffed grouse flush the dreaded West Nile virus out of their bodies. A state Department of Natural Resources study found that 20% of blood samples showed antibodies consistent with West Nile exposure. None of the 188 samples had evidence of the virus present in their hearts. “Birds are surviving and clearing the virus from their bodies,” said Alaina Gerrits, assistant upland game ecologist. Among humans, about one in 150 people develop severe illness from the mosquito-carried virus, including encephalitis and meningitis. The question now: Can new knowledge move us toward protecting humans.