Progress of Trachoma Mapping in Mainland Tanzania: Results of Baseline Surveys from 2012 to 2014

Abstract

Purpose: Following surveys in 2004–2006 in 50 high-risk districts of mainland Tanzania, trachoma was still suspected to be widespread elsewhere. We report on baseline surveys undertaken from 2012 to 2014. Methods: A total of 31 districts were surveyed. In 2012 and 2013, 12 at-risk districts were selected based on proximity to known trachoma endemic districts, while in 2014, trachoma rapid assessments were undertaken, and 19 of 55 districts prioritized for baseline surveys. A multi-stage cluster random sampling methodology was applied whereby 20 villages (clusters) and 36 households per cluster were surveyed. Eligible participants, children aged 1–9 years and people aged 15 years and older, were examined for trachoma using the World Health Organization simplified grading system. Results: A total of 23,171 households were surveyed and 104,959 participants (92.3% of those enumerated) examined for trachoma signs. A total of 44,511 children aged 1–9 years and 65,255 people aged 15 years and older were examined for trachomatous inflammation–follicular (TF) and trichiasis, respectively. Prevalence of TF varied by district, ranging from 0.0% (95% confidence interval, CI 0.0–0.1%) in Mbinga to 11.8% (95% CI 6.8–16.5%) in Chunya. Trichiasis prevalence was lowest in Urambo (0.03%, 95% CI 0.00–0.24%) and highest in Kibaha (1.08%, 95% CI 0.74–1.43%). Conclusion: Only three districts qualified for mass drug administration with azithromycin. Trichiasis is still a public health problem in many districts, thus community-based trichiasis surgery should be considered to prevent blindness due to trachoma. These findings will facilitate achievement of trachoma elimination objectives.

Trachoma in Viet Nam: results of 11 surveillance surveys conducted with the Global Trachoma Mapping Project

“…We also sought to trim fieldwork time by not collecting household-level data on access to water and sanitation, which was routinely integrated within trachoma surveys in other GTMP sub-projects. [20][21][22][23][24][25][26] Due to a paucity of cases of active trachoma, our graders did not undertake live subject inter-grader agreement exercises to qualify for survey deployment, but were instead assessed using a standard set of 50 conjunctival photographs. During the GTMP, Lao PDR 27 and Cambodia 28 circumvented a similar lack of local cases by sending trainee graders to Ethiopia for field training and certification, but this was not possible for Viet Nam.…”

Understanding hard-to-reach communities: local perspectives and experiences of trachoma control among the pastoralist Maasai in northern Tanzania

“…Whilst trachoma is estimated to affect 17% of the population of Tanzania (WHO, 2017), the majority of trachoma-endemic areas are predominantly inhabited by the Maasaia pastoral ethnic group. The baseline prevalence of trachomatous inflammationfollicular (TF) in Longido District was greater than 50% in 2004 (Masesa et al, 2007;Mwingira et al, 2016). Longido District received more than five rounds of MDA before undertaking trachoma impact surveys in 2018, showing that TF had declined to 7.2%; however, MDA was continued as per the World Health Organization (WHO) guidelines.…”

The Importance of Failure: How Doing Impact Surveys That Fail Saves Trachoma Programs Money

“…Per-capita GDP and population density were set at $936 and 123 people per km 2 , respectively: real-world data from the United Republic of Tanzania in 2017. These choices were consistent with the scenario under consideration: the WHO recommends that programs achieve at least 80% coverage when undertaking antibiotic MDA 3 ; where baseline TF prevalence is 10-29.9%, an impact survey to determine whether or not MDA should continue would normally be undertaken before the fourth round, the United Republic of Tanzania is trachoma endemic, 36 C survey can also depend on N. The standard error of a prevalence estimate decreases as the sampling fraction increases, allowing smaller sample sizes (for the same level of precision) with smaller underlying populations. In practice, sample sizes do not vary much across the WHOrecommended EU population range: a decrease in EU population size from 250,000 to 100,000 decreases the estimated sample size requirement for 1-to 9-year-olds by only 2.3-3.2%, depending on the other parameters used in the calculation.…”

“…Per-capita gross domestic product (GDP) and population density were set at $936 and 123 people per km 2 , respectively: real-world data from the United Republic of Tanzania in 2017. These choices were consistent with the scenario under consideration: WHO recommends that programs achieve at least 80% coverage when undertaking antibiotic MDA 3 ; where baseline TF prevalence is 10–29.9%, an impact survey to determine whether or not MDA should continue would normally be undertaken before the fourth round, the United Republic of Tanzania is trachoma endemic, 36 and so on. The derived estimates were $0.13 (2015 USD; 95% CI: 0.08–0.17), $0.18 (0.11–0.23), $0.20 (0.12–0.26), $0.23 (0.14–0.29), $0.28 (0.17–0.35), and 0.39 (0.24–0.49) for EUs of 500,000, 250,000, 200,000, 150,000, 100,000, and 50,000 people, respectively.…”