Cascading effect of economic globalization on human risks of scrub typhus and tick-borne rickettsial diseases

Chi Chien Kuo, Jing Lun Huang, Pei Yun Shu, Pei Lung Lee, Douglas A. Kelt, Hsi Chieh Wang

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)1803-1816
Number of pages14
JournalEcological Applications
Volume22
Issue number6
DOIs
Publication statusPublished - 2012 Sep 1

Keywords

  • Agricultural policy
  • Agriculture
  • Economic globalization
  • Orientia tsutsugamushi
  • Rice
  • Rickettsia spp.
  • Taiwan rice paddies
  • Tick
  • Trombiculid mite
  • Vector-borne diseases
  • World Trade Organization

ASJC Scopus subject areas

  • Ecology

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