Upper Respiratory Tract Infections - Respiratory Infections and Lung Disorders

Respiratory Infections and Lung Disorders 
Pathogens frequently spread from one individual to another by way of the respiratory tract. Droplets from a single sneeze may be loaded with billions of bacteria or viruses. The mu­cous membranes are protected by mucus production and by the constant beating of the cilia, but if the number of infec­tive agents is large and/or the individual's resistance is re­duced, an upper respiratory infection can result.

Upper Respiratory Tract Infections
The upper respiratory tract consists of the nose, the phar­ynx, and the larynx. Upper respiratory infections (URI) can spread from the nasal cavities to the sinuses, to the middle ears, and to the larynx. Viral infections sometimes lead to secondary bacterial infections. What we call "strep throat" is a primary bacterial infection caused by Streptococcus pyo­genes that can lead to a generalized upper respiratory infec­tion and even a systemic (affecting the body as a whole) infection. While antibiotics have no effect on viral infec­tions, they are successfully used for most bacterial infec­tions, including strep throat.
Common Cold
A cold is a viral infection that usually begins as a scratchy sore throat, followed by a watery mucous discharge from the nasal cavities. Fevers are rare, and symptoms are usually mild, requiring little or no medication. Although colds have a short duration, the immunity they provide is also brief. Since there are estimated to be over 150 cold-causing viruses, acquiring immunity to all of them is very difficult.
Cold vaccines are not in wide use, and because colds are viral in nature, antibiotics are not helpful. Since viruses reproduce inside cells, it is difficult to develop drugs that will kill the virus without affecting the cell itself.
Influenza
Influenza (flu) is a viral infection of the respiratory tract that is usually accompanied by aches and pains in the joints and fever. Influenza usually lasts longer than a cold. Immunity is possible, but only the vaccine developed for the particular flu virus prevalent that season can usually be successful in protecting the individual. Since influenza viruses constantly mutate, immunity does not build up, and a new viral illness rapidly spreads from person to per­son and from place to place. Pandemics, in which a newly
mutated influenza virus spreads throughout the world, oc­cur regularly, about every 10 years.
Sinusitis
Sinusitis is an infection of the sinuses, cavities within the facial skeleton that drain into the nasal cavities. Only about 1-3% of upper respiratory infections are ac­companied by sinusitis. Sinusitis develops when nasal con­gestion blocks the tiny openings leading to the sinuses. Symptoms include postnasal discharge as well as facial pain that worsens when the patient bends forward. Pain and tenderness usually occur over the lower forehead or over the cheeks. If the latter, toothache is also a complaint. Successful treatment depends on restoring proper drainage of the sinuses. Even a hot shower and sleeping upright can be helpful. Otherwise, spray decongestants are preferred over oral antihistamines, which thicken rather than liquefy the material trapped in the sinuses.
Otitis Media
Otitis media is a bacterial infection of the middle ear. The middle ear is not a part of the respiratory tract, but this infection is considered here because it is a complication of­ten seen in children who have a nasal infection. Infection can spread by way of the auditory tube that leads from the nasopharynx to the middle ear. Pain is the pri­mary symptom of a middle ear infection. A sense of full­ness, hearing loss, vertigo (dizziness), and fever may also be present. Antibiotics almost always bring about a full re­covery, and a recurrence is most likely due to a new infec­tion. Drainage tubes (called tympanostomy tubes) are sometimes placed in the eardrum of children with multi­ple recurrences to help prevent buildup of fluid in the mid­dle ear and the possibility of hearing loss. Normally, the tubes slough out with time.
Tonsillitis
Tonsillitis occurs when tonsils become inflamed and en­larged. Tonsils are masses of lymphatic tissue that occur in the pharynx. The tonsils in the dorsal wall of the nasopharynx are often called adenoids. The tonsils 're­move many of the pathogens that enter the pharynx; there­fore, they are a first line of defense against invasion of the body. If tonsillitis occurs frequently and enlargement makes breathing difficult, the tonsils can be removed surgi­cally in a tonsillectomy. Fewer tonsillectomies are per­formed today than in the past because it is now known that tonsils serve an important function in defending the body against infection.
Laryngitis
Laryngitis is an infection of the larynx with an accompa­nying hoarseness leading to the inability to talk in an audi­ble voice. Usually laryngitis disappears with treatment of the upper respiratory infection. Persistent hoarseness without the presence of an upper respiratory in­fection is one of the warning signs of cancer and therefore should be looked into by a physician.
Upper respiratory infections due to viruses, such as colds and influenza, are not treatable by antibiotics, but bacterial infections, such as otitis media and strep throat, usually respond to antibiotic therapy.