Forecasting the elimination of active trachoma: An empirical model

• Published in: PLoS neglected tropical diseases Vol. 16; no. 7; p. e0010563
• Main Authors: Renneker, Kristen K, Emerson, Paul M, Hooper, P. J, Ngondi, Jeremiah M
• Format: Journal Article
• Language: English
• Published: San Francisco Public Library of Science 11.07.2022; Public Library of Science (PLoS)
• Subjects: Biology and Life Sciences; Control; Earth Sciences; Mathematical analysis; Mathematical models; Medicine and Health Sciences; People and Places; Physical Sciences; Public health; Research and Analysis Methods; Statistical analysis; Statistical models; Surveying; Trachoma; Tropical diseases; Ethiopia
• ISSN: 1935-2735; 1935-2727; 1935-2735
• DOI: 10.1371/journal.pntd.0010563

Background Great progress has been made toward the elimination of trachoma as a public-health problem. Mathematical and statistical models have been used to forecast when the program will attain the goal of the elimination of active trachoma, defined as prevalence of trachomatous inflammation-follicular in 1-9 year olds (TF.sub.1-9) <5%. Here we use program data to create an empirical model predicting the year of attaining global elimination of TF.sub.1-9. Methodology/Principal findings We calculated the mean number of years (95% CI) observed for an implementation unit (IU) to move from a baseline TF.sub.1-9 prevalence [greater than or equal to]5% to the elimination threshold, based on the region (Ethiopia vs. non-Ethiopia) and baseline prevalence category. Ethiopia IUs had significantly different rates of reaching the TF.sub.1-9 elimination threshold after a trachoma impact survey (TIS) compared to non-Ethiopia IUs across all baseline categories. We used those estimates to predict when remaining active trachoma-endemic IUs (TF.sub.1-9 [greater than or equal to]5%) would have their last round of mass drug administration (MDA) based on the mean number of years required and number of MDA rounds already completed. Our model predicts that elimination of TF.sub.1-9 will be achieved in 2028 in Ethiopia (95% CI: 2026-2033) and 2029 outside of Ethiopia (95% CI: 2023-2034), with some IUs in East Africa predicted to be the last requiring MDA globally. Conclusions/Significance Our empirical estimate is similar to those resulting from previous susceptible-infectious-susceptible (SIS) and mathematical models, suggesting that the forecast achievement of TF.sub.1-9 elimination is realistic with the caveat that although disease elimination progress can be predicted for most IUs, there is an important minority of IUs that is not declining or has not yet started trachoma elimination activities. These IUs represent an important barrier to the timely global elimination of active trachoma.