Upper Respiratory Tract Infection

Upper respiratory tract infections (URTIs) are defined as non-specific infections of the breathing mechanism of the body. The upper respiratory tract includes the nose, mouth, sinus, throat, and the upper portion of the bronchial passages that lead to the lungs.

The respiratory tract is a common location for the entry of pathogens by way of airborne microorganisms. It is estimated that as many as 10,000 such foreign bodies enter the body in this fashion each day. Most of these organisms are trapped by the immune system's first line of defense, the layer of sticky mucus that lines the interior of the nasal and throat passages. Most of the particles are stuck to the mucus layer, and ultimately swallowed and destroyed in the stomach.

The second line of defense in the immune system located in the upper respiratory system are the adenoids and the tonsils. Positioned at the back of the throat between the nasal passages and the larynx, these small organs are a part of the lymphatic system, designed to protect the body from harmful organisms by trapping any such bodies that pass over them. URTIs generally occur when either bacteria are able to bypass the immune system defenses, or by airborne virus.

The most frequent of URTIs is the common cold, which is transmitted by way of viruses that are spread from person to person, with a greater frequency in the winter months. The typical adult person in North America will develop between two and four colds in the course of a year. The most severe form of these viruses is influenza, which can cause significant communitywide health problems. Nasal congestion, sneezing, a sore throat, and a generalized feeling of weakness are the most frequent symptoms of the common cold. Although a cold by itself is rarely a completely debilitating event, the negative effect of a cold on athletic performance can be dramatic.

The mouth may be the means by which a cold virus enters the body. The URTIs that affect the mouth specifically are trench mouth (a very painful and progressive infection of the lining of the mouth and throat) and herpes simplex type 1 (an infection that causes lesions and sores inside the mouth). This condition is unrelated to herpes simplex type 2, a sexually transmitted disease.

Pharyngitis is the term that includes a broad range of infections of the throat. The sore throat is a condition linked to the presence of a common cold. Because the condition is viral in nature, the sore throat cannot be eradicated in the body through antibiotics, which are only effective against bacteria-based conditions. The bacterial agent that does cause a serious throat infection is the streptococcal organism, the precipitator of strep throat. Strep throat is a progressive condition usually accompanied by fever and significant headaches.

Infections can also attack other specific locations with in the upper respiratory tract. The most common of these are sinusitis, laryngitis, and tonsillitis. Sinusitis is an infection that presents itself with symptoms of facial pain in the area of the sinus passages, toothache as a result of excess pressure from the infected passage upon the upper teeth, and large amounts of discolored mucus from the nose. Laryngitis is an infection of the larynx, commonly referred to as the voice box, which impairs the person's ability to speak clearly.

Tonsillitis is a condition affecting the tonsils, whose function as a part of the lymphatic system is to filter bacteria out of the body; tonsillitis occurs when the tonsils become overwhelmed by the bacteria. When the condition is caused by bacteria, such as streptococcal, antibiotics are prescribed and the typical course of healing is between 10 to 14 days. In severe cases, the tonsils are surgically removed.

The tracheobrochial area, located between the trachea (throat) and the bronchial tubes leading to the lungs, is another common site for URTIs. Tracheobronchitis is an infection that causes a significant cough and wheezing sensation in the person; this condition can persist for one to three weeks.

The mechanism by which bacterial agents are able to establish themselves within the upper respiratory tract is complex. The nasal passages have a natural complement of bacteria, which compete with any bacterial invaders for space within the passages. Without such space, the foreign bacteria cannot multiply sufficiently to pose any threat to the healthy function of the respiratory system. To infect the upper respiratory system, the invading bacteria must be both airborne and alive at the time that it enters the body. The bacteria must then be deposited in a susceptible host tissue, and once established in the respiratory tract, the variant illness will be developed within anywhere from 12 to 36 hours, depending on the speed with which the condition spreads.

see also Asthma, exercise induced; Cardiorespiratory function; Immune system.