Subacute Thyroiditis-Is it Really Linked to Viral Infection?

Area of Science:

• Endocrinology
• Virology
• Epidemiology

Background:

• Subacute thyroiditis (SAT) is an inflammatory thyroid condition often following thyrotoxicosis.
• Its exact cause remains uncertain, though viral triggers like enteroviruses are suspected due to seasonal incidence patterns.
• Enteroviruses exhibit seasonal distribution aligning with SAT occurrence.

Purpose of the Study:

• To investigate the causal link between enteroviruses and subacute thyroiditis (SAT).
• To assess the impact of reduced viral circulation during the COVID-19 pandemic on SAT seasonality.
• To explore associations between various viruses and SAT frequency.

Main Methods:

• Analysis of German national hospital registry data (2015-2022).
• Utilized surveillance data for infectious diseases.
• Employed statistical modeling, including seasonality analysis, autoregression, and Granger causality tests.

Main Results:

• Confirmed higher SAT incidence in females with a late summer peak until 2019, coinciding with enterovirus seasonality.
• SAT patterns remained consistent in 2020 despite reduced enterovirus and other pathogen circulation due to hygiene measures.
• SAT seasonality in 2021-2022 was unaffected by the COVID-19 pandemic.

Conclusions:

• The study provides strong evidence against Echoviruses and Coxsackieviruses being the cause of SAT.
• No association was found between SAT and other analyzed viruses, including Influenza, Parainfluenza, Rhinovirus, and Human Coronaviruses (including SARS-CoV-2).
• The findings indicate that SAT's seasonality is not driven by enteroviruses or other common respiratory viruses.