Epidemiology
Sore throat accounts for 1% to 2% of all patient visits to a primary care physician in the US. This accounts for approximately 7.3 million annual visits for children and 6.7 million for adults.[3] Accurate figures with regard to acute laryngitis are difficult to collect, because it is generally unreported. One review conducted by the Royal College of General Practitioners in the UK in 2010 reported an average incidence of 6.6 cases of laryngitis and tracheitis per 100,000 patients (all ages) per week.[4]
In addition, the incidence of chronic laryngitis is not well established but has been estimated as 3.47 diagnoses per 1000 people per year.[5]
Laryngitis is most common in children between 6 months and 3 years old.[6]
Most cases of acute laryngitis are caused by viral infections. Viral agents tend to have annual periods of peak prevalence, such as rhinovirus infections in fall and spring, and influenza virus infection epidemics generally from December to April. Laryngitis may occur due to croup or epiglottitis. The recorded incidence of epiglottitis in the US declined between 1980 and 1990. These epidemiologic changes have been ascribed to the introduction of the Haemophilus influenzae type B (Hib) vaccination.[7]
Diphtheria is encountered rarely in the US but can still infect children and adults who are immunocompromised or have not received vaccinations. Worldwide, diphtheria is still endemic in areas such as Africa, Latin American, Asia, the Middle East, and parts of Europe where immunization coverage with diphtheria toxoid-containing vaccines is suboptimal. Since 2011, large outbreaks have been reported in Indonesia, Laos, Haiti, Venezuela, Yemen, Bangladesh, and west Africa. In 2022, the World Health Organization (WHO) reported 5856 global cases of diphtheria; although that number may underrepresent the true number recorded given the COVID-19 pandemic.[8]
Tuberculous laryngitis is historically a sequela of pulmonary tuberculosis (TB), but can present without pulmonary involvement. In developed countries, TB is associated with people who have emigrated from endemic areas (e.g., China and India) or have a history of HIV infection.[9] The WHO estimates that there were 10.8 million cases of TB in 2023, with over 80% of cases and deaths occurring in low- and middle-income countries.[10] However, over 95% of cases and deaths are in developing countries.[10] Approximately 8 million people worldwide are coinfected with HIV and TB, the majority of whom live in sub-Saharan Africa, the Indian subcontinent, and South East Asia.[11] Laryngeal candidiasis is more common in immune-suppressed patients, as well as among immune-competent patients using inhaled corticosteroids or prolonged courses of antibiotics.[12]
Both acute and chronic laryngeal inflammation can be caused by phonotrauma, and/or exposure to environmental irritants.[4]
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