Passengers and close contacts, some with symptoms, are being monitored until not contagious: From Santa Clara, California, to Nebraska, to Emory University in Atlanta.

The virus's long incubation period is making it difficult for investigators to pinpoint where the infection occurred.

More than a half dozen U.S. states are monitoring individuals who have either been exposed to or exhibiting symptoms of hantavirus, the disease at the center of a deadly cruise ship outbreak. The ...