Department of Microbiology and Virology, Faculty of Medicine, Medical University Varna, Varna, Bulgaria.
Cent Eur J Public Health. 2024 Sep;32(3):178-182. doi: 10.21101/cejph.a7792.
Temperature is the most important environmental variable associated with the varicella frequency across the world. The present study compares the incidence of varicella in the districts of Bulgaria against some climatic factors and tries to find environmental variables which account for the differences in the varicella distribution observed among the Bulgarian districts.
The 28 Bulgarian districts were used as units of observation and their average 10-year varicella incidence (2009-2018) was tested for correlation with the standard bioclimatic variables of WorldClim, version 2.
The WorldClim estimates for the annual mean temperature, the maximal temperature of the warmest month, the minimal temperature of the coldest month, the mean temperature of the coldest quarter, and the solar radiation inversely and not significantly correlated with the average 10-year varicella frequency. The precipitation of the warmest quarter and the wind speed correlated positively and also not significantly. Only the mean temperature of the driest quarter correlates significantly with the incidence at district level (Spearman's rank correlation coefficient of -0.45, p = 0.02). The mean of average 10-year varicella incidence rates among districts with driest quarter during the winter (January, February, March) was 387.6 ± 114.1, while among districts with driest quarter during the summer/autumn (July, August, September or August, September, October) 283.3 ± 102.1 (p = 0.02, ANOVA test).
Dry winter and/or wet summer appear as significant determinants for the fluctuant spread of varicella infection in Bulgaria.
温度是与世界各地水痘发病率最相关的最重要环境变量。本研究比较了保加利亚各地区的水痘发病率与某些气候因素，并试图找到能解释观察到的保加利亚各地区水痘分布差异的环境变量。
将 28 个保加利亚地区作为观察单位，检验其平均 10 年水痘发病率（2009-2018 年）与 WorldClim 版本 2 的标准生物气候变量的相关性。
WorldClim 对年平均温度、最热月最高温度、最冷月最低温度、最冷月平均温度和太阳辐射的估计与平均 10 年水痘发病率呈负相关，但不显著。温暖季度的降水量和风速呈正相关，但也不显著。只有最干燥季度的平均温度与地区水平的发病率显著相关（Spearman 等级相关系数为-0.45，p=0.02）。冬季（1 月、2 月、3 月）最干燥季度的地区平均 10 年水痘发病率平均值为 387.6±114.1，而夏季/秋季（7 月、8 月、9 月或 8 月、9 月、10 月）最干燥季度的地区平均 10 年水痘发病率平均值为 283.3±102.1（p=0.02，ANOVA 检验）。
干燥的冬季和/或潮湿的夏季似乎是保加利亚水痘感染波动传播的重要决定因素。
