Chae Joon-Seok, Adjemian Jennifer Zipser, Kim Heung-Chul, Ko Sungjin, Klein Terry A, Foley Janet
Veterinary Internal Medicine, College of Veterinary Medicine, Seoul National University, Seoul, Korea.
Vector Borne Zoonotic Dis. 2008 Apr;8(2):265-75. doi: 10.1089/vbz.2007.0190.
Granulocytic anaplasmosis (GA) and monocytic ehrlichiosis (ME) are maintained in wild rodent reservoirs and tick vectors in the Republic of Korea. This study investigated the prevalence of 2 tick-borne pathogens, Anaplasma phagocytophilum and Ehrlichia chaffeensis, in wild rodents and ticks in central Korea to identify any significant associations with existing or changing climatic conditions. Specifically, the goal of this study was to develop simple models for the probability of occurrence of an epidemic of GA or ME as a function of climate in an area in a given year. Climatic data from 2 regions, Munsan and Dongducheon, Gyeonggi, in central Korea (between the Demilitarized Zone and Seoul, latitude between 37 degrees N-38 degrees N and longitude between 127 degrees E-128 degrees E), were analyzed with respect to the prevalence of GA and ME in Paju, Yoncheon, Pocheon, and Dongducheon for the period from 2001 to 2005. Rates of A. phagocytophilum and E. chaffeensis decreased as the total yearly precipitation levels and daily humidity increased, and as the daily mean sunshine hours decreased. Rates of A. phagocytophilum and E. chaffeensis from rodent ticks and rodents increased in the fall season. Linear regression analyses evaluating the numbers of positive samples by sample type found that rodent ticks were 6.64 times more likely to be actively infected with A. phagocytophilum than grass ticks or rodents, though the likelihood of any samples testing positive for this pathogen decreased by 0.17 as the annual mean level of precipitation increased by 1 mm. For E. chaffeensis, rodents were 15.67 times more likely to be infected than ticks. Logistic regression analyses evaluating each sample separately found that the odds of infection with A. phagocytophilum were nearly 5 times greater for rodents than ticks. In these analyses, precipitation was one potential factor to account for the prevalence of tickborne diseases.
粒细胞无形体病（GA）和单核细胞埃立克体病（ME）在韩国的野生啮齿动物宿主和蜱虫媒介中传播。本研究调查了韩国中部野生啮齿动物和蜱虫中两种蜱传病原体——嗜吞噬细胞无形体和查菲埃立克体的流行情况，以确定与现有或变化的气候条件之间是否存在显著关联。具体而言，本研究的目标是建立简单模型，以预测给定年份某地区GA或ME疫情发生的概率与气候的函数关系。分析了韩国中部京畿道文山和东豆川两个地区（位于非军事区和首尔之间，北纬37度至38度，东经127度至128度）2001年至2005年期间GA和ME在坡州、涟川、抱川和东豆川的流行情况的气候数据。嗜吞噬细胞无形体和查菲埃立克体的感染率随着年总降水量和每日湿度的增加以及每日平均日照时数的减少而降低。秋季，来自啮齿动物蜱虫和啮齿动物的嗜吞噬细胞无形体和查菲埃立克体感染率上升。通过样本类型评估阳性样本数量的线性回归分析发现，啮齿动物蜱虫感染嗜吞噬细胞无形体的活跃感染可能性是草蜱或啮齿动物的6.64倍，不过随着年平均降水量每增加1毫米，该病原体任何样本检测呈阳性的可能性降低0.17。对于查菲埃立克体，啮齿动物感染的可能性是蜱虫的15.67倍。分别评估每个样本的逻辑回归分析发现，啮齿动物感染嗜吞噬细胞无形体的几率几乎是蜱虫的5倍。在这些分析中，降水量是解释蜱传疾病流行情况的一个潜在因素。
