Upper respiratory tract infection
An upper respiratory tract infection (URTI) is an illness caused by an acute infection, which involves the upper respiratory tract, including the nose, sinuses, pharynx, larynx or trachea.[3][4] This commonly includes nasal obstruction, sore throat, tonsillitis, pharyngitis, laryngitis, sinusitis, otitis media, and the common cold.[5]: 28 Most infections are viral in nature, and in other instances, the cause is bacterial.[6] URTIs can also be fungal or helminthic in origin, but these are less common.[7]: 443–445
Upper respiratory tract infection
Cause[edit]
In terms of pathophysiology, rhinovirus infection resembles the immune response. The viruses do not cause damage to the cells of the upper respiratory tract, but rather cause changes in the tight junctions of epithelial cells. This allows the virus to gain access to tissues under the epithelial cells and initiate the innate and adaptive immune responses.[5]: 27
Up to 15% of acute pharyngitis cases may be caused by bacteria, most commonly Streptococcus pyogenes, a group A streptococcus in streptococcal pharyngitis ("strep throat").[11] Other bacterial causes are Streptococcus pneumoniae, Haemophilus influenzae, Corynebacterium diphtheriae, Bordetella pertussis, and Bacillus anthracis.
Sexually transmitted infections have emerged as causes of oral and pharyngeal infections.[12]
Prevention[edit]
Vaccination against influenza viruses, adenoviruses, measles, rubella, Streptococcus pneumoniae, Haemophilus influenzae, diphtheria, Bacillus anthracis, and Bordetella pertussis may prevent them from infecting the URT or reduce the severity of the infection.
Epidemiology[edit]
Children typically have two to nine viral respiratory illnesses per year.[6] In 2013, 18.8 billion cases of URTIs were reported.[31] As of 2014, they caused about 3,000 deaths, down from 4,000 in 1990.[8] In the United States, URTIs are the most common infectious illness in the general population, and are the leading reasons for people missing work and school.
Dietary research[edit]
Weak evidence suggests that probiotics may be better than a placebo treatment or no treatment for preventing upper respiratory tract infections.[32]