J Med Entomol. 2014 May;51(3):694-701. doi: 10.1603/me13140.
Changes in the structure of managed red pine forests in Wisconsin caused by interacting root- and stem-colonizing insects are associated with increased abundance of the blacklegged tick, Ixodes scapularis Say, in comparison with nonimpacted stands. However, the frequency and variability of the occurrence of tick-borne pathogens in this coniferous forest type across Wisconsin is unknown. Red pine forests were surveyed from 2009 to 2013 to determine the prevalence of Borrelia burgdorferi and Anaplasma phagocytophilum in questing I. scapularis nymphs. Polymerase chain reaction analysis revealed geographical differences in the nymphal infection prevalence (NIP) of these pathogens in red pine forests. In the Kettle Moraine State Forest (KMSF) in southeastern Wisconsin, NIP of B. burgdorferi across all years was 35% (range of 14.5-53.0%). At the Black River State Forest (BRSF) in western Wisconsin, NIP of B. burgdorferi across all years was 26% (range of 10.9-35.5%). Differences in NIP of B. burgdorferi between KMSF and BRSF were statistically significant for 2010 and 2011 and for all years combined (P < 0.05). NIP ofA. phagocytophilum (human agent) averaged 9% (range of 4.6-15.8%) at KMSF and 3% (range of 0-6.4%) at BRSF, and was significantly different between the sites for all years combined (P < 0.05). Differences in coinfection of B. burgdorferi and A. phagocytophilum were not statistically significant between KMSF and BRSF, with an average of 3.4% (range of 1.7-10.5%) and 2.5% (range of 0-5.5%), respectively. In 2013, the density of infected nymphs in KMSF and BRSF was 14 and 30 per 1000m2, respectively, among the highest ever recorded for the state. Differences in the density of nymphs and NIP among sites were neither correlated with environmental factors nor time since tick colonization. These results document significant unexplained variation in tick-borne pathogens between coniferous forests in Wisconsin that warrants further study.
威斯康星州受管理的红云松林中，由根系和茎干定殖昆虫引起的结构变化与黑腿蜱（Ixodes scapularis Say）的丰度增加有关，与未受影响的林分相比，黑腿蜱的丰度更高。然而，这种针叶林类型中 tick-borne 病原体的发生频率和可变性在威斯康星州尚不清楚。2009 年至 2013 年，对红云松林进行了调查，以确定在觅食的 I. scapularis 若虫中伯氏疏螺旋体和嗜吞噬细胞无形体的流行率。聚合酶链反应分析显示，红云松林中这些病原体的若虫感染流行率（NIP）存在地理差异。在威斯康星州东南部的 Kettle Moraine 州立森林（KMSF）中，所有年份的 B. burgdorferi 的 NIP 为 35%（范围为 14.5-53.0%）。在威斯康星州西部的黑河州立森林（BRSF）中，所有年份的 B. burgdorferi 的 NIP 为 26%（范围为 10.9-35.5%）。KMSF 和 BRSF 之间 B. burgdorferi 的 NIP 差异在 2010 年和 2011 年以及所有年份的组合上均具有统计学意义（P < 0.05）。KMSF 的 A. phagocytophilum（人类病原体）的 NIP 平均为 9%（范围为 4.6-15.8%），BRSF 的 NIP 为 3%（范围为 0-6.4%），所有年份的组合在两个地点之间均存在统计学差异（P < 0.05）。KMSF 和 BRSF 之间 B. burgdorferi 和 A. phagocytophilum 的共感染差异无统计学意义，平均分别为 3.4%（范围为 1.7-10.5%）和 2.5%（范围为 0-5.5%）。2013 年，KMSF 和 BRSF 中感染若虫的密度分别为每 1000m² 14 和 30 只，是该州有记录以来的最高密度。地点之间的若虫密度和 NIP 差异既与环境因素无关，也与蜱定殖时间无关。这些结果表明，威斯康星州针叶林中 tick-borne 病原体存在显著的未解释的变异，这值得进一步研究。
