Department of Wildlife, Fish, and Conservation Biology, University of California, One Shields Avenue, Davis, California 95616, USA.
Ecol Appl. 2012 Sep;22(6):1803-16. doi: 10.1890/12-0031.1.
The increase in global travel and trade has facilitated the dissemination of disease vectors. Globalization can also indirectly affect vector-borne diseases through the liberalization of cross-border trade, which has far-reaching, worldwide effects on agricultural practices and may in turn influence vectors through the modification of the ecological landscape. While the cascading effect of economic globalization on vector-borne diseases, sometimes acting synergistically with regional agricultural policy, could be substantial and have significant economic, agricultural, and public health implications, research into this remains very limited. We evaluated how abandonment of rice paddies in Taiwan after joining the World Trade Organization, along with periodic plowing, an agricultural policy to reduce farm pests in abandoned fields can unexpectedly influence risks to diseases transmitted by ticks and chiggers (larval trombiculid mites), which we collected from their small-mammal hosts. Sampling was limited to abandoned (fallow) and plowed fields due to the challenge of trapping small mammals in flooded rice paddies. Striped field mice (Apodemus agrarius) are the main hosts for both vectors. They harbored six times more ticks and three times more chiggers in fallow than in plowed plots. The proportion of ticks infected with Rickettsia spp. (etiologic agent of spotted fever) was three times higher in fallow plots, while that of Orientia tsutsugamushi (scrub typhus) in chiggers was similar in both treatments. Fallow plots had more ground cover and higher vegetation than plowed ones. Moreover, ticks and chiggers in both field types were dominated by species known to infest humans. Because ticks and chiggers should exhibit very low survival in flooded rice paddies, we propose that farm abandonment in Taiwan, driven by globalization, may have inadvertently led to increased risks of spotted fever and scrub typhus. However, periodic plowing can unintentionally mitigate vector burdens. Economic globalization can have unexpected consequences on disease risk through modification of the agricultural landscape, but the outcome may also be influenced by agricultural policies, calling for further research on vector-borne diseases and their control from broader perspectives.
全球旅行和贸易的增加促进了疾病媒介的传播。全球化也可以通过跨境贸易自由化间接影响媒介传播疾病，这种自由化对农业实践产生了深远的、全球性的影响，并可能通过改变生态景观来影响媒介。虽然经济全球化对媒介传播疾病的级联效应，有时与区域农业政策协同作用，可能是巨大的，并对经济、农业和公共卫生产生重大影响，但对此的研究仍然非常有限。我们评估了台湾加入世界贸易组织后放弃稻田以及定期犁地的情况，这是一种减少农田害虫的农业政策，这可能会意外地影响蜱虫和恙螨（幼虫沙螨）传播疾病的风险，我们从它们的小型哺乳动物宿主中收集了这些疾病。由于在稻田中捕捉小型哺乳动物具有挑战性，因此采样仅限于废弃（休耕）和犁耕的田地。条纹田鼠（Apodemus agrarius）是这两种媒介的主要宿主。它们在休耕田中携带的蜱虫数量是犁耕田的六倍，携带的恙螨数量是犁耕田的三倍。在休耕田中，感染立克次体病（斑疹热病因）的蜱虫比例比犁耕田高三倍，而恙螨中感染恙虫病东方体（丛林斑疹伤寒）的比例在两种处理中相似。休耕田的地面覆盖物和植被比犁耕田高。此外，两种田型的蜱虫和恙螨都以已知会感染人类的物种为主。由于蜱虫和恙螨在被洪水淹没的稻田中应该很难存活，我们提出台湾由于全球化而导致的农业废弃可能无意中增加了斑疹热和丛林斑疹伤寒的风险。然而，定期犁地可以无意中减轻载体负担。经济全球化可能通过改变农业景观对疾病风险产生意想不到的后果，但农业政策也可能影响结果，呼吁从更广泛的角度进一步研究媒介传播疾病及其控制。
