Pharyngitis refers to the inflammation of the pharynx, which is the area located at the back of the throat. This condition commonly manifests as a sore throat, causing discomfort. It is not a disease in itself but rather a symptom that frequently indicates an underlying issue. Understanding the various factors that can lead to this inflammation is important for addressing the discomfort effectively.
Common Viral Causes
Viral infections account for a large majority of pharyngitis cases. Common cold viruses, such as rhinovirus and coronavirus, are frequent culprits, with rhinovirus alone causing approximately 20% of pharyngitis cases. Rhinovirus infections typically begin with nasal dryness or irritation, followed by a sore throat, and generally manifest as mild, self-limiting illnesses.
Influenza viruses, responsible for the flu, also commonly cause pharyngitis. Adenoviruses can lead to pharyngitis, particularly in children, sometimes presenting as pharyngoconjunctival fever with a sore throat, fever, and eye inflammation. Epstein-Barr virus (EBV), the cause of infectious mononucleosis, is another viral cause, often resulting in marked throat inflammation, swollen tonsils, and enlarged lymph nodes. Most viral pharyngitis cases resolve spontaneously within approximately one week to ten days.
Bacterial Causes
Bacterial infections represent a smaller, though important, proportion of pharyngitis cases. The most recognized bacterial cause is Streptococcus pyogenes, commonly known as Group A Streptococcus (GAS) or strep throat, responsible for 20-40% of pharyngitis in children and 5-15% in adults.
This infection is particularly prevalent in children aged 5 to 15 years, and can cause a sudden onset of sore throat, fever, and swollen tonsils often with white patches or streaks of pus. Unlike viral pharyngitis, strep throat usually lacks typical cold symptoms like cough or runny nose.
If left untreated, GAS pharyngitis can lead to more serious complications, including rheumatic fever, which can affect the heart, and kidney inflammation. While S. pyogenes is the primary bacterial concern, other less common bacterial agents can also cause pharyngitis. These include Arcanobacterium haemolyticum, which primarily affects adolescents and young adults and can present with a sore throat, fever, and sometimes a rash. Other bacteria like Chlamydophila pneumoniae and Mycoplasma pneumoniae have also been identified as causes of pharyngitis.
Other Contributing Factors
Beyond infections, various non-infectious and less common factors can contribute to pharyngitis. Allergies, particularly those causing post-nasal drip, can lead to a persistent sore throat as mucus irritates the pharynx. Environmental irritants also play a role; exposure to pollutants like smoke, chemicals, and dry air can directly irritate the throat lining.
Gastroesophageal reflux disease (GERD), where stomach acid flows back into the esophagus and throat, is another non-infectious cause that can result in chronic pharyngitis and a burning sensation. Fungal infections, such as oral thrush caused by Candida albicans, can also cause pharyngitis, especially in individuals with weakened immune systems or those using certain medications like inhaled corticosteroids.
Identifying the Likely Cause
Distinguishing the cause of pharyngitis often involves observing accompanying symptoms. Viral pharyngitis commonly presents with cold-like symptoms, such as a runny nose, cough, sneezing, and sometimes conjunctivitis. Fevers associated with viral infections can vary, from low-grade to higher temperatures, and fatigue may be present.
In contrast, bacterial pharyngitis, particularly strep throat, typically features a sudden onset of a severely sore throat, fever, and often swollen tonsils that may have white patches or pus. A notable absence of cough and runny nose can help differentiate strep throat from viral infections.
For non-infectious causes, allergies might be suspected if the sore throat is accompanied by itching, sneezing, and watery eyes, especially during specific seasons. A persistent sore throat accompanied by heartburn or a sour taste might indicate GERD.