causes(mumps, 'enlarged salivary glands',
       ['in particular one or both of the parotid glands are enlarged
         and painful']).
causes(measles, fever, ['the fever can be quite high']).
causes(measles, 'Koplik spots',
       ['these are small white spots in the mouth',
        'typically they start bleeding when rubbed']).
causes(measles, conjunctivitis, 
       ['this is associated with watery eyes',
        'other ocular signs may also occur']).
causes(rubella, rash, ['the rash starts on the face, and then spreads to
       the trunk and arms']).
causes(rubella, fever, [none]).
causes(fever, 'bodytemp > 38', [none]).
causes(mumps, orchitis, ['this is inflammation of the testes']).
causes(orchitis, 'testicular shrinkage',
       ['this occurs in about 50% of male patients',
        'it is a potential cause of sterility']  ).