A US warship has essentially been quarantined at sea for over two months and has been unable to make a port call due to an outbreak of a viral infection similar to mumps. Twenty-five sailors and Marines aboard the USS Fort McHenry amphibious warship have been diagnosed with parotitis, which causes symptoms similar to mumps, according to US military officials. Until CNN asked about the incident, the US military had not disclosed it. The illness first broke out in December, with the most recent case being reported on March 9.