Fieldworkers conducting a survey of trachoma, Kenya

A group of fieldworkers conducting a survey of trachoma in Kenya. Surveys are one aspect of community assessment. Although surveys generally allow the disease status of a community to be determined, they face a number of challenges. These include: selecting the sample to be surveyed; ensuring that grading of trachoma is accurate; the absence of older children (eg. at school); and clustering of disease (when the inadvertent selection of a household with an unusually high, or low, prevalence can make the sample unrepresentative of the community).