Worries about a new virus first detected in China that’s infected tens of thousands of people globally are making a mark on the economy of a nine-state region in the Midwest and Plains.The Mid-American Business Conditions Index sank in February to 52.8, from 57.2, in January, according to a survey report issued Monday.“This month’s softer reading plus the mounting negative impacts from the (virus) should concern policymakers regarding the strength of the economy,” said Creighton University economist Ernie Goss, who oversees the survey.