口腔單純皰疹（oral herpes simplex）主要由第一型單純皰疹病毒（Herpes Simplex Virus Type 1, HSV-1）所引起，病毒感染後可潛伏於神經節中，並於特定條件下再活化造成疾病復發。雖然第一型單純皰疹病毒感染相當常見，但其是否具有季節性變化及與氣候因子之關聯仍缺乏一致結論。

本研究收集國立成功大學醫學院附設醫院2015年至2023年間口腔單純皰疹病例資料，分析病例數之時間分布特徵，並探討氣溫、相對濕度、日照時數及紫外線指數等氣候因子與病例數之關聯性。研究方法包括傅立葉分析、自相關分析、相關性分析及迴歸模型建構。

結果顯示，各月份病例數分布未呈現明顯年度季節性差異。傅立葉分析顯示病例數可能存在約6個月及21個月之週期性波動，其中以21個月週期較為明顯。相關性分析發現平均氣溫及日照時數與病例數之關聯性較弱，相對濕度與病例數呈弱負相關，而高強度紫外線暴露可能與病例數增加相關。

綜合而言，本研究未發現口腔單純皰疹具有明顯的一年週期季節性變化，但病例數可能存在較長週期波動現象。相對濕度可能與疾病復發具有一定關聯，然而其影響程度有限，而高強度紫外線暴露則可能與病例數增加有關，顯示口腔單純皰疹之復發可能受到多重環境及宿主因素共同影響。

Oral herpes is primarily caused by Herpes Simplex Virus Type 1 (HSV-1). Following the initial infection, the virus can remain latent in the nerve ganglia and reactivate under specific conditions, leading to disease recurrence. Although HSV-1 infection is highly prevalent, whether it exhibits seasonal variations and how it correlates with climatic factors remain inconclusive.
This study collected data on oral herpes cases from National Cheng Kung University Hospital between 2015 and 2023 to analyze the temporal distribution characteristics of case counts and explore their association with climatic factors, including temperature, relative humidity, sunshine hours, and the ultraviolet (UV) index. The research methodologies employed included Fourier analysis, autocorrelation analysis, correlation analysis, and regression model construction.
The results indicated that the distribution of monthly case counts did not exhibit significant annual seasonal differences. Fourier analysis revealed that case counts might possess cyclical fluctuations of approximately 6 months and 21 months, with the 21-month cycle being more pronounced. Correlation analysis showed that mean temperature and sunshine hours were not associated with case counts, whereas relative humidity was weakly negatively correlated with case counts. High UV exposure (UV index ≥8) might be associated with higher case counts. Regression analysis further demonstrated that incorporating relative humidity improved the model's explanatory power.
In conclusion, this study did not find a distinct annual seasonal pattern for oral herpes, though the number of cases may exhibit longer-term cyclical fluctuations. Relative humidity and UV exposure might share a certain correlation with the occurrence of the disease; however, its impact is limited. This suggests that the onset of oral herpes is likely influenced by a complex interplay of multiple environmental and host factors.

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