Definition of masked. 1  1 : marked by the use of masks a masked ball. 2  2 : failing to present or produce the usual symptoms : latent a masked infection a masked virus.
1 HSV-1. 2  This is the type that usually causes cold sores or fever blisters around your mouth, though it can be spread to your genital area during oral sex. 3  Recurrences are much less frequent than they are with HSV-2 infection. 4  HSV-2.
Respiratory syncytial virus (RSV) is a virus that causes respiratory infections. It is the most common cause of bronchiolitis (inflammation of the bronchioles within the lungs) and pneumonia among infants and children under one year of age.