Upper respiratory tract infections are majorly caused by an acute infection which involves larynx, nose, sinuses and pharynx. Up to 15% of acute pharyngitis cases occur due to Group A Streptococcus (Bacteria) resulting in “strep throat”. Bacterial infections generally require targeted therapy. Viruses predominate upper respiratory tract infections.
The most common upper respiratory tract infection are mentioned below;
- Pharyngitis: Inflammation of the tonsils, hypopharynx, pharynx and uvula.
- Rhinitis: Inflammation of the nasal mucosa
- Laryngitis: Inflammation of the larynx
- Tracheitis: Inflammation of the subglottic area and trachea.
Physiology of the pathogen
URI’s directly invade the mucosal lining of the upper airway. Bacterial infections are either spread person to person or it may manifest due to a viral URI. Inoculation of the bacterial pathogen may occur when secretions are transferred by body contact ( touching your mouth or nose with your hand which has been exposed to the pathogen) or directly inhaling bacterial droplets from a person who is coughing or sneezing.
After inoculation, the pathogen faces barriers like physical, mechanical, cellular or humoral immune defenses. The hair lining in nose traps the pathogen. Similarly, the mucous membrane prevents the invasion of the bacterial pathogen in the upper respiratory tract. Normal nasopharyngal flora (staphylococcal and streptococcal species) inhibit the action of the invading pathogen.
Frequency of incidence
URIs are the most common form of illness which affects the general population. Group A Streptococcal Bacteria approximately cause 5-15% of all pharyngitis infections which finally accounts for several million streptococcal pharyngitis cases each year. It is rarely diagnosed in children below two years.
Mortality
Mortality due to URIs alone is a rare incidence although it may act a channel for infections of other structures, resulting in bronchitis, sepsis, meningitis, otitis media and other infections. This may lead to severe complications which causes rare deaths.
