Abstract
Abstract: :
Purpose: It is well known that various factors such as physical or emotional stress or alternation in the immune status of the host affect recurrence of herpes simplex virus (HSV) keratitis. It is difficult to predict recurrence of HSV keratitis although we have experienced high incidence of recurrence during winter month in Japan, suggesting possible existence of correlation between environmental factors such as low temperature and recurrence of HSV keratitis. The purpose of this study was to assess the seasonal trend of these recurrences. Methods: The clinical records of HSV keratitis patients who visited Tokyo Women’s Medical University over the past 12 years (1991–2003) were analyzed retrospectively for the number of recurrence of dendritic and stromal keratitis. The day of recurrence were classified into 4 seasons, spring month (March ∼ May), summer month (June ∼ August), autumn month(September ∼ November) and winter month (December ∼ February) and were assessed for seasonal trend. We also statistically analyzed the correlation between frequency of recurrence and temperature in Tokyo. Clinical diagnosis of herpetic keratitis was verified by serial slit–lamp examinations, laboratory studies including virus isolation and/or immunomorphologic evaluation of corneal epithelial scrapings. Results: A total of 332 dendritic keratitis and 202stromal keratitis recurrences were recorded among 110 patients. One hundred and forty (42.2%) recurrences of dendritic keratitis occurred during winter months and 49 (14.8%) in summer months. Same seasonal effects were observed within recurrence of stromal kerataitis. Significant statistical negative correlation was observed between temperature and the incidence of dendritic keratitis although not with stromal keratitis. Pearson’s correlation coefficient (r) and the corresponding P values for these correlations were r=–0.409 and–0.332, and P = 0.019 and 0.067 respectively. Conclusions: Our data suggests an association between the risk of recurrent HSV keratitis and season of the year. According to the fact that increased number of recurrence occurred in the winter month, low temperature may be one of the risk factor of recurrence of HSV keratitis.
Keywords: herpes simplex virus • keratitis • clinical (human) or epidemiologic studies: prevalence/incidence