Seto Edmund Y W, Knapp Freyja, Zhong Bo, Yang Changhong
School of Public Health, University of California, Berkeley, 140 Warren Hall, Berkeley, CA 94720, USA.
Geospat Health. 2007 May;1(2):233-41. doi: 10.4081/gh.2007.271.
The real exposure to many of the tropical diseases is difficult to assess at the individual-level due to problems of recall, self-reported diaries, personnel requirements, and altered behaviour related to observation. We present a study in an area endemic for Schistosoma japonicum in which global positioning system (GPS) receivers were used for personal time-activity monitoring to assess water-contact associated with schistosomiasis transmission. The study subjects were equipped with a vest with an embedded GPS receiver for 8-hour periods. The resulting data were used to create hourly time-activity maps, which were subsequently used in interviews to ascertain the timing and location of the water-contacts. Based on a sample of twenty-four 8-hour person-days we found that individuals averaged 1.4 +/- 1.2 water-contacts per day, and were surprisingly mobile, with 39% of the participants having spent time out of the village (0.8 +/- 1.4 hours outside of village). Such mobility suggests the need for further research into social patterns that may facilitate the spread of parasites, and contribute to sustained transmission. We present an assessment of the accuracy of cheaper commercially- available GPS units that have shown promise in such applications. We feel that a speed-filtering method is effective in managing measurement errors commonly encountered during personal activity monitoring with GPS. We conclude that personal GPS units can help reduce recall problems associated with other methods of assessing water-contact, and that they offer valuable insights into time-activity patterns that influence schistosomiasis transmission.
由于存在回忆问题、自我报告日记、人员需求以及与观察相关的行为改变等因素，很难在个体层面评估对许多热带疾病的实际暴露情况。我们在日本血吸虫病流行地区开展了一项研究，其中使用全球定位系统（GPS）接收器进行个人时间活动监测，以评估与血吸虫病传播相关的水接触情况。研究对象配备了带有嵌入式GPS接收器的背心，为期8小时。所得数据用于创建每小时的时间活动地图，随后在访谈中使用这些地图来确定水接触的时间和地点。基于24个8小时人日的样本，我们发现个体平均每天有1.4±1.2次水接触，而且移动性惊人，39%的参与者在村外度过了时间（村外0.8±1.4小时）。这种移动性表明需要进一步研究可能促进寄生虫传播并导致持续传播的社会模式。我们对在这类应用中显示出前景的更便宜的商用GPS设备的准确性进行了评估。我们认为速度过滤方法在管理GPS个人活动监测过程中常见的测量误差方面是有效的。我们得出结论，个人GPS设备有助于减少与其他评估水接触方法相关的回忆问题，并且它们为影响血吸虫病传播的时间活动模式提供了有价值的见解。
