Design and validation of a trachomatous trichiasis-only survey

Overview

The Fifty-first World Health Assembly adopted resolution WHA51.11 in 1998, which targets the global elimination of trachoma as a public health problem by 2020 (1). The strategy recommended to achieve that goal is encapsulated by the acronym “SAFE”, which represents: Surgery for individuals with trachomatous trichiasis (TT; the late blinding stage of trachoma); and Antibiotics, Facial cleanliness and Environmental improvement (2). The A, F and E interventions are delivered to entire districts in which active (inflammatory) trachoma is common in order to treat ocular infection with Chlamydia trachomatis, the causative organism of trachoma, and sustainably reduce its transmission. 

The work described in this report was commissioned by WHO to guide recommendations for optimizing the design of a TT-only survey. Doing that work provided an opportunity to also evaluate the precision of TT prevalence estimates in general.