Surveillance of potential hosts and vectors of scrub typhus in Taiwan.
Surveillance of potential hosts and vectors of scrub typhus in Taiwan.
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DOI：
10.1186/s13071-015-1221-7
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发表时间：
2015-12-01
影响因子：
3.2
通讯作者：
Wang HC
中科院分区：
文献类型：
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作者：
Kuo CC;Lee PL;Chen CH;Wang HC
恙虫病是一种致命的传染病，由感染恙虫病东方体 (OT) 的幼虫螨虫（即恙螨）传播，近几十年来，一些国家出现了恙虫病。恙虫种类及其脊椎动物宿主的鉴定对于评估环境变化下人类感染斑疹伤寒的风险至关重要，但台湾仍缺乏对恙虫及其宿主的深入和广泛的调查。从台湾九个县的鼩鼱和啮齿动物身上采集恙螨，并通过巢式聚合酶链反应 (PCR) 检测 OT 感染情况。 PCR 产物进一步测序以揭示可能的 OT 菌株。通过免疫荧光抗体测定评估啮齿类动物的 OT 暴露情况。最后，每个县的恙虫病发病率与恙虫感染的数量和患病率、啮齿动物的血清阳性率以及恙虫的 OT 阳性率相关。黄鼠是数量最多（占 1,285 只）、分布最广（分布于九个县）的小型哺乳动物物种，是大多数恙螨的栖息地（占 128,520 只恙螨的 76.4%）。德利细螨 (Leptotrombidium deliense) 是最常见（占所有已识别恙螨的 64.9%）且分布广泛（存在于七个县）的恙螨种类，但在冬季气温低于其他研究地点的两个县（马祖和金门）的寒冷季节，被苍白细螨或盾片细螨取代。 876 只啮齿类动物的 OT 暴露血清阳性率为 43.0%，347 只恙螨池的 OT 阳性率为 55.9%，在 107 个成功测序的样本中鉴定出 15 种 OT 菌株。恙虫病的发病率与恙虫载量、恙虫感染流行率、恙虫血清阳性率呈正相关，但与恙虫的 OT 阳性率无关。我们的研究表明，R. Losa 是恙虫的主要宿主，台湾恙虫种类存在地理和季节变化。它还强调了识别恙虫病媒及其脊椎动物宿主的重要性，以更好地预测快速环境变化下人类感染斑疹伤寒的风险。
Scrub typhus is a lethal infectious disease vectored by larval trombiculid mites (i.e. chiggers) infected with Orientia tsutsugamushi (OT) and recent decades have witnessed an emergence of scrub typhus in several countries. Identification of chigger species and their vertebrate hosts is fundamental for the assessment of human risks to scrub typhus under environmental changes, but intensive and extensive survey of chiggers and their hosts is still lacking in Taiwan. Chiggers were collected from shrews and rodents in nine counties of Taiwan and were assayed for OT infections with nested polymerase chain reaction (PCR). PCR products were further sequenced to reveal probable OT strains. Rodents were assessed for OT exposure by immunofluorescent antibody assay. Lastly, incidence rate of scrub typhus in each county was associated with loads and prevalence of chigger infestations, seropositivity rate in rodents, and OT positivity rate in chiggers. Rattus losea was the most abundant (48.7 % of 1,285 individuals) and widespread (occurred in nine counties) small mammal species and hosted the majority of chiggers (76.4 % of 128,520 chiggers). Leptotrombidium deliense was the most common (64.9 % of all identified chiggers) and widespread (occurred in seven counties) chigger species but was replaced by Leptotrombidium pallidum or Leptotrombidium scutellare during the cold seasons in two counties (Matsu and Kinmen) where winter temperatures were lower than other study sites. Seropositivity rate for OT exposure in 876 assayed rodents was 43.0 % and OT positivity rate in 347 pools of chiggers was 55.9 %, with 15 OT strains identified in the 107 successfully sequenced samples. Incidence rate of scrub typhus was positively correlated with chigger loads, prevalence of chigger infestations, seropositivity rate but not OT positivity rate in chiggers. Our study reveals R. losea as the primary host for chiggers and there exists a geographical and seasonal variation in chigger species in Taiwan. It also emphasizes the importance of recognition of chigger vectors and their vertebrate hosts for a better prediction of human risks to scrub typhus under rapid environmental changes.