492786159_85999_990x742A physician died at a Nebraska hospital on Monday after contracting the disease in Sierra Leone, where he was working. A New York physician came down with Ebola last month after working in West Africa, sparking quarantines for returning health workers in some states. Earlier in October, a man died in Dallas after becoming infected in Liberia. But Ebola isn’t the tropical disease that’s most likely to cause health problems in the United States—not by a long shot. A handful of other tropical diseases pose much more realistic threats. And they’re spread by insects, which can’t be quarantined. More