Prince George’s County officials closed a Hyattsville elementary school over the weekend after one of its teachers tested positive for the H1N1, or swine flu, virus. University Park Elementary School will be shuttered for up to two weeks as officials hope to contain the spread of the contagion. World health officials have warned that swine flu is an imminent pandemic but say that its threat to public health is not appreciably worse than the common flu. Maryland is home to at least 15 probable cases of the swine flu. Virginia is home to three more, including a Washington and Lee University student who tested positive over the weekend. There has been one death from swine flu in the U.S., a baby. In Mexico, about 16 people have died from the disease. Last week, a World Bank official and a White House security aide were both announced to have contracted the disease