Trachoma Prevalence After Discontinuation of Mass Azithromycin Distribution

Transactions of the Royal Society of Tropical Medicine and Hygiene

Prada

et al. 2021

Self Cite

Background Progress towards elimination of trachoma as a public health problem has been substantial, but the coronavirus disease 2019 (COVID-19) pandemic has disrupted community-based control efforts. Methods We use a susceptible-infected model to estimate the impact of delayed distribution of azithromycin treatment on the prevalence of active trachoma. Results We identify three distinct scenarios for geographic districts depending on whether the basic reproduction number and the treatment-associated reproduction number are above or below a value of 1. We find that when the basic reproduction number is <1, no significant delays in disease control will be caused. However, when the basic reproduction number is >1, significant delays can occur. In most districts, 1 y of COVID-related delay can be mitigated by a single extra round of mass drug administration. However, supercritical districts require a new paradigm of infection control because the current strategies will not eliminate disease. Conclusions If the pandemic can motivate judicious, community-specific implementation of control strategies, global elimination of trachoma as a public health problem could be accelerated.

“…The rare apparent resurgence reported from a few subcritical districts may be attributable to a combination of misclassification and measurement error. 14 , 28 , 29 …”

Section: Discussionmentioning

confidence: 99%

Implications of the COVID-19 pandemic in eliminating trachoma as a public health problem

Blumberg

Transactions of the Royal Society of Tropical Medicine and Hygiene

Prada

et al. 2021

Self Cite

“…The rare apparent resurgence reported from a few subcritical districts may be attributable to a combination of misclassification and measurement error. 8,22,23…”

Section: Discussionmentioning

confidence: 99%

Implications of the COVID-19 pandemic on eliminating trachoma as a public health problem

Blumberg¹,

Prada

et al. 2020

Preprint

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Background: Progress towards elimination of trachoma as a public health problem has been substantial, but the COVID-19 pandemic has disrupted community-based control efforts. Methods: We use a susceptible-infected model to estimate the impact of delayed distribution of azithromycin treatment on the prevalence of active trachoma. Results: We identify three distinct scenarios for geographic districts depending on whether the basic reproduction number and the treatment-associated reproduction number are above or below a value of one. We find that when the basic reproduction number is below one, no significant delays in disease control will be caused. However, when the basic reproduction number is above one, significant delays can occur. In most districts a year of COVID-related delay can be mitigated by a single extra round of mass drug administration. However, supercritical districts require a new paradigm of infection control because the current strategies will not eliminate disease. Conclusion: If the pandemic can motivate judicious, community-specific implementation of control strategies, global elimination of trachoma as a public health problem could be accelerated.

“…The model for C. trachomatis transmission is based on a previously described framework. 15 , 16 The original population-based, deterministic model based on ordinary differential equations has subsequently been adapted to be stochastic 14 and then further developed here to a fully stochastic individual-based model. The model incorporates current knowledge of the natural history and transmission of trachoma, including direct person-to-person transmission with infectivity proportional to an individual's bacterial load, children acting as a core group for transmission, individuals being susceptible to repeated infections and the persistence of TF after clearance of ocular C. trachomatis infection.…”

Section: Methodsmentioning

confidence: 99%

“… 4 , 18 , 20 These aspects are represented within the model framework, with bacterial load, duration of ID and D for each individual assumed to decrease with each subsequent infection following negative exponentials. 14 , 16 Age, current infection/disease status and total number of infections for each individual are explicitly incorporated; the model runs in 1-wk time steps.…”

Section: Methodsmentioning

confidence: 99%

“…Building on previously developed mathematical models for trachoma transmission, 14–16 we explore the impact of an interruption to community-level MDA in a range of endemic settings. Our individual-based stochastic model incorporates some key aspects of ocular C. trachomatis infection biology, including acquired immunity leading to decreased duration of infection with repeated infection and allows simulation of some of the variability in response to MDA observed in empirical studies.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Modelling trachoma post-2020: opportunities for mitigating the impact of COVID-19 and accelerating progress towards elimination

Transactions of the Royal Society of Tropical Medicine and Hygiene

Blumberg²,

Callahan

et al. 2021

Self Cite

Background The COVID-19 pandemic has disrupted planned annual antibiotic mass drug administration (MDA) activities that have formed the cornerstone of the largely successful global efforts to eliminate trachoma as a public health problem. Methods Using a mathematical model we investigate the impact of interruption to MDA in trachoma-endemic settings. We evaluate potential measures to mitigate this impact and consider alternative strategies for accelerating progress in those areas where the trachoma elimination targets may not be achievable otherwise. Results We demonstrate that for districts that were hyperendemic at baseline, or where the trachoma elimination thresholds have not already been achieved after three rounds of MDA, the interruption to planned MDA could lead to a delay to reaching elimination targets greater than the duration of interruption. We also show that an additional round of MDA in the year following MDA resumption could effectively mitigate this delay. For districts where the probability of elimination under annual MDA was already very low, we demonstrate that more intensive MDA schedules are needed to achieve agreed targets. Conclusion Through appropriate use of additional MDA, the impact of COVID-19 in terms of delay to reaching trachoma elimination targets can be effectively mitigated. Additionally, more frequent MDA may accelerate progress towards 2030 goals.