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. 2015;22(6):394-402.
doi: 10.3109/09286586.2015.1081249.

Estimating the Future Impact of a Multi-Pronged Intervention Strategy on Ocular Disease Sequelae Caused by Trachoma: A Modeling Study

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Estimating the Future Impact of a Multi-Pronged Intervention Strategy on Ocular Disease Sequelae Caused by Trachoma: A Modeling Study

Manoj Gambhir et al. Ophthalmic Epidemiol. 2015.

Abstract

Purpose: Trachoma control programs are underway in endemic regions worldwide. They are based on the SAFE strategy (Surgery for trichiasis, Antibiotic distribution, Facial cleanliness, and Environmental improvement). Although much is known about the effect of community-wide treatment with antibiotics on the prevalence of Chlamydia trachomatis, the impact of the SAFE strategy on severe ocular disease sequelae (the main focus of the Global Elimination of blinding Trachoma by 2020 program) remains largely unknown.

Methods: We use a mathematical model to explore the impact of each of the components of the SAFE strategy, individually and together, on disease sequelae, arising from repeat infection and subsequent conjunctival scarring. We ask whether two elimination goals, to reduce the prevalence of trachomatous trichiasis to 1 per 1000 persons, and the incidence of corneal opacity to 1 per 10,000 persons per annum, are achievable, and which combinations of interventions have the greatest impact on these indicators.

Results: In high prevalence communities (here, >20% infection of children aged 1-9 years), a combination of efforts is needed to bring down sustainably the prevalence and incidence of ocular disease sequelae.

Conclusion: The mass delivery of antibiotics is highly beneficial for the clearance of infection, inflammation and prevention of subsequent scarring, but needs to be supplemented with sustained reductions in transmission and surgery to consider realistically the elimination of blindness by the year 2020.

Keywords: Blindness; Chlamydia trachomatis; elimination program; mathematical modeling; ocular sequelae.

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Figures

FIGURE 1.
FIGURE 1.
Trachoma disease model diagram. Compartmental disease model based on the ladder of infection framework of Gambhir and colleagues with an extension to take into account development of corneal opacities (CO) from the population of those who previously developed trachomatous scarring (TS) and then trichiasis (TT). The disease states TS and TT are developed through repeat infection, but development of CO is not linked to further infection and occurs at a constant rate as a consequence of mechanical corneal damage incurred by those with TT (see Supplemental Appendix for model parameters).
FIGURE 2.
FIGURE 2.
Response of trachoma disease sequelae prevalence to treatment. Simulated age-dependent prevalence of disease sequelae (trachomatous scarring [TS], dark blue lines [left]; trachomatous trichiasis [TT], light blue lines [middle]; and corneal opacities [CO], green lines [right]), in a high-endemicity trachoma setting at baseline, following three treatment schedules; (A) antibiotics (A) only, at high intensity; (B) A+ transmission reduction (TR) both at high intensity; (C) surgery (S) + A + TR all at high intensity. In each plot, the thicker lines represent baseline prevalence over age and each subsequent lower curve is plotted at 5-year intervals such that the bottom-most curves represent the prevalence levels 20 years after baseline. In (A), the markers indicate the prevalence values of TS, TT, and CO observed in Kongwa, Tanzania with error bars representing 95% confidence intervals of the collected dataset.
FIGURE 3.
FIGURE 3.
Response of trachomatous trichiasis (TT) prevalence and corneal opacity (CO) incidence to treatment. Trend in: (A) prevalence of TT, and (B) incidence of CO through time following three treatment schedules initiated at 0 years (black arrow). From the uppermost to the bottom curve, the population is subjected to mass drug administration (MDA) at high intensity (dark solid line), MDA + transmission reduction (TR) both at high intensity (upper dark dotted line), and MDA + TR + surgery (S), all at high intensity (lower light dotted line). The horizontal dotted line represents the relevant threshold for the Global Elimination of blinding Trachoma by 2020 (GET2020) program goals (a level of one case of CO per 10,000 persons per annum, and a prevalence of one case of TT per 1000 persons).

References

    1. WHO. Prevention of blindness and visual impairment: Trachoma. 2009. Accessed June 25, 2009 from: http://www.who.int/blindness/causes/trachoma/en/index.html
    1. Kuper H, Solomon AW, Buchan J, et al. A critical review of the SAFE strategy for the prevention of blinding trachoma. Lancet Infect Dis. 2003;3:372–381. - PubMed
    1. Mariotti SP, Pascolini D, Rose-Nussbaumer J. Trachoma: global magnitude of a preventable cause of blindness. Br J Ophthalmol. 2009;93:563–568. - PubMed
    1. Taylor HR. Trachoma grading: a new grading scheme. Rev Int Trach Pathol Ocul Trop Subtrop Sante Publique. 1987;(64):175–181. - PubMed
    1. ITI Frequently Asked Questions. 2012. Accessed June 5, 2012 from: http://trachoma.org/iti-frequently-asked-questions

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