Respiratory infections are caused by a variety and different types of viruses. Respiratory infections can be spread in different ways. The body respiratory infections include sinus, nose, throat (pharynx), voice box (larynx), windpipe (trachea), mouth and lungs. The leading viruses that are causes for the common cold are Rhinovirus, corona-virus, and adenovirus. Influenza is one the viruses, infect the upper respiratory system and sometimes spread to the lungs causing pneumonia. Respiratory syncytial virus (RSV) is the virus that causes a respiratory infection called bronchiolitis in infants and toddlers.