Trachoma surveys 2000-2005: results, recent advances in methodology, and factors affecting the determination of prevalence.

With the advent of VISION 2020 and GET 2020 inaugurated by the World Health Organization, it is timely to provide an update of the methodology employed in trachoma surveys, given that a significant number of individuals in many undeveloped and developing countries still suffer from this ophthalmic disease. The advent of Trachoma Rapid Assessment and Asymmetrical Sampling Rapid Trachoma Assessment has enabled faster identification of trachoma-endemic areas, though population-based surveys are still required prior to intervention. Research into factors affecting prevalence determination has shown that mobility, clustering, and seasonality should all be taken into account regarding survey design. In addition, recent advances in laboratory testing have given us new insight into trachoma infection patterns and a better understanding of the disease course. In this review, we examine advances in survey methodology and the results of trachoma surveys since 1999, and other issues relevant to the determination of trachoma prevalence. Based on recent findings, we recommend that pooled nucleic acid amplification testing be used to augment clinical assessment in areas where trachoma prevalence is greater than 20%. Further, we suggest that trachoma follicular and trachoma follicular or trachoma intense, as markers of the disease, be reported separately.