Inflammation Center, Division of Infectious Diseases, University of Helsinki and Helsinki University Hospital, POB 348, FIN-00029 HUS, Helsinki, Finland.
Department of Bacteriology and Immunology, University of Helsinki, P.O. Box 21, FIN-00014 Helsinki, Finland.
Travel Med Infect Dis. 2018 Jul-Aug;24:37-43. doi: 10.1016/j.tmaid.2018.01.006. Epub 2018 Feb 2.
Travellers' diarrhoea (TD) is a common health problem among visitors to the (sub)tropics. Much research deals with aetiology, prevention, and post-infection sequalae, yet the data may not allow comparisons due to incompatible definitions of TD and No TD control groups.
The impact of defining TD and No TD control groups was explored by revisiting our recent data. We set up two TD groups: classical TD i.e. ≥3 loose or liquid stools/day and WHO TD (diarrhoea as defined by the WHO) i.e. any diarrhoea, and four No TD groups by TD definition and timing (no classical/WHO TD during travel, no ongoing classical/WHO TD).
TD was recorded for 37% versus 65% of subjects when using classical versus WHO definitions, respectively; the proportions of the various pathogens proved similar. The strictest criterion for the No TD control group (no WHO TD during travel) yielded pathogens among 61% and the least strict (no ongoing classical TD) among 73% of the travellers; the differences were greatest for enteroaggregative Escherichia coli and Campylobacter.
Definition of TD and control group design substantially impact on TD study results. The WHO definition yields more cases, but the pathogen selection is similar by both definitions. Design of the No TD control group was found critical: only those remaining asymptomatic throughout the journey should be included.
旅行者腹泻（TD）是前往（亚热带）地区游客中常见的健康问题。许多研究涉及病因、预防和感染后后遗症，但由于 TD 和非 TD 对照组的定义不兼容，数据可能不允许进行比较。
通过重新审视我们最近的数据，探讨了定义 TD 和非 TD 对照组的影响。我们设立了两个 TD 组：经典 TD，即每天≥3 次稀便或水样便；和世界卫生组织 TD（世界卫生组织定义的腹泻），即任何腹泻。通过 TD 定义和时间设立了四个非 TD 对照组：旅行期间无经典/WHO TD，无持续的经典/WHO TD。
使用经典定义和世界卫生组织定义时，分别有 37%和 65%的受试者记录了 TD；各种病原体的比例证明相似。非 TD 对照组（旅行期间无世界卫生组织 TD）最严格的标准导致 61%的旅行者出现病原体，最宽松的标准（无持续经典 TD）导致 73%的旅行者出现病原体；差异最大的是肠聚集性大肠杆菌和弯曲菌。
TD 的定义和对照组的设计极大地影响了 TD 研究结果。世界卫生组织的定义产生了更多的病例，但两种定义的病原体选择相似。非 TD 对照组的设计被发现至关重要：只有那些在整个旅行过程中保持无症状的人才能被纳入。
