Evaluation of a Single Dose of Azithromycin for Trachoma in Low-Prevalence Communities

Prevalence of Trachoma following Implementation of the SAFE Strategy in Three Local Government Areas of Taraba State, North Eastern Nigeria

INTRODUCTION

In 2019-2020, one round of antibiotic mass drug administration (MDA) was implemented for trachoma elimination purposes in Donga, Gashaka, and Ussa local government areas (LGAs) of Taraba State, Nigeria, following baseline surveys in 2009 (Donga and Gashaka) and 2013-2014 (Ussa). Here, trachoma prevalence post-MDA in these three LGAs is reported.

METHODS

In 2019 (Gashaka and Ussa) and 2020 (Donga), population-based, cross-sectional surveys were conducted following World Health Organization (WHO) guidance. A two-stage cluster sampling strategy was used. All residents of selected households aged ≥1 year were examined by Tropical Data-certified graders for trachomatous inflammation-follicular (TF) and trachomatous trichiasis (TT) using the WHO simplified trachoma grading scheme. Data on water, sanitation, and hygiene (WASH) access were also collected.

RESULTS

A total of 1,883 households participated. From these households, 4,885 children aged 1-9 years were enumerated, and 4,866 (99.6%) examined. There were 5,050 eligible adults (aged ≥15 years) enumerated in the same households, of whom 4,888 (96.8%) were examined. Age-adjusted TF prevalence in children aged 1-9 years was 0.22% (95% CI: 0.00-0.65) in Donga, 0.0% in Gashaka, and 0.19% (95% CI: 0.00-0.44) in Ussa. The age- and gender-adjusted TT prevalence unknown to the health system in adults aged ≥15 years was 0.08% (95% CI: 0.00-0.19) in Donga, 0.02% (95% CI: 0.00-0.06) in Gashaka, and 0.10% (95% CI: 0.01-0.18) in Ussa. In Donga, Gashaka, and Ussa, respectively, 66%, 49% and 63% of households had access to an improved drinking water source, and 68%, 56% and 29% had access to an improved latrine.

CONCLUSION

In all LGAs, the elimination thresholds for TF and TT unknown to the health system have been attained in the target age groups. These LGAs should be re-surveyed after 2 years to show that reductions in TF prevalence have been sustained in the absence of MDA. Health authorities should continue to improve WASH facilities to reduce the risk of later recrudescence.

Monitoring transmission intensity of trachoma with serology

Trachoma, caused by ocular Chlamydia trachomatis infection, is targeted for global elimination as a public health problem by 2030. To provide evidence for use of antibodies to monitor C. trachomatis transmission, we collated IgG responses to Pgp3 antigen, PCR positivity, and clinical observations from 19,811 children aged 1-9 years in 14 populations. We demonstrate that age-seroprevalence curves consistently shift along a gradient of transmission intensity: rising steeply in populations with high levels of infection and active trachoma and becoming flat in populations near elimination. Seroprevalence (range: 0-54%) and seroconversion rates (range: 0-15 per 100 person-years) correlate with PCR prevalence (r: 0.87, 95% CI: 0.57, 0.97). A seroprevalence threshold of 13.5% (seroconversion rate 2.75 per 100 person-years) identifies clusters with any PCR-identified infection at high sensitivity ( >90%) and moderate specificity (69-75%). Antibody responses in young children provide a robust, generalizable approach to monitor population progress toward and beyond trachoma elimination.

Monitoring transmission intensity of trachoma with serology

Trachoma, caused by ocular Chlamydia trachomatis infection, is targeted for global elimination as a public health problem by 2030. To provide evidence for use of antibodies to monitor C. trachomatis transmission, we collated IgG responses to Pgp3 antigen, PCR positivity, and clinical observations from 19,811 children aged 1- 9 years in 14 populations. We demonstrate that age-seroprevalence curves consistently shift along a gradient of transmission intensity: rising steeply in populations with high levels of infection and active trachoma and becoming flat in populations near elimination. Seroprevalence (range: 0-54%) and seroconversion rates (range: 0-15 per 100 person-years) correlate with PCR prevalence (r: 0.87, 95% CI: 0.57, 0.97). A seroprevalence threshold of 13.5% (seroconversion rate 2.75 per 100 person-years) identifies clusters with any PCR-identified infection at high sensitivity (>90%) and moderate specificity (69-75%). Antibody responses in young children provide a robust, generalizable approach to monitor population progress toward and beyond trachoma elimination.

To eliminate trachoma: Azithromycin mass drug administration coverage and associated factors among adults in Goro district, Southeast Ethiopia

Background

Globally, although effective prevention strategies and treatment are available, trachoma remains the major cause of infectious loss of sight. Trachoma is a predominant neglected disease in Ethiopia, and there is a 40.4% prevalence of active trachoma in the Goro district, Southeast Ethiopia. World Health Organization (WHO) recommends azithromycin mass treatment of at least 80% coverage to eliminate trachoma, even though the coverage of azithromycin mass treatment has not been studied yet in depth. Thus, this study aimed to assess the coverage and factors influencing azithromycin mass treatment uptake among adults in Goro district, Southeast Ethiopia.

Methods

A community-based cross-sectional study was conducted from April 1^st to April 30th, 2021 among all adults aged 15 years old and above. The multistage sampling technique was used to select 593 study respondents. A structured interviewer-administered questionnaire was used. Data were entered into Epi-Data version 3.1 and analyzed using SPSS version 23.0 software. Descriptive analysis and binary logistic regression analysis were used to analyze the data. Adjusted odds ratios (AOR) along with a 95% confidence interval (CI) and p-value < 0.05 were used to declare the strength and the significance of association, respectively.

Results/Principal findings

Five hundred and seventy eight study participants with a 97% response rate were included. The proportion of azithromycin mass drug administration coverage was found to be 75.80%; 95% CI: (72%-79%) in this study. Having better knowledge about trachoma (AOR = 2.36; 95% CI: 1.19–4.70), having better knowledge about azithromycin mass treatment (AOR = 4.19; 95% CI: 2.19–7.98), being educated (AOR = 7.20; 95% CI: 1.02–51.09), a campaign conducted at the quiet time (off-harvesting/planting season) (AOR = 6.23; 95% CI: 3.23–11.98), heard about the serious adverse effect from others (AOR = 0.25; 95% CI: 0.10–0.59) and being a volunteer to take azithromycin in the next campaign (AOR = 5.46; 95% CI: 2.76–10.79) were significantly associated with azithromycin mass drug administration coverage.

Conclusions/Significance

The proportion of azithromycin mass treatment coverage of this study was lower than the WHO minimum target coverage. Thus, strengthening awareness, enhancing azithromycin mass trachoma treatment messages, and conducting campaigns off-season outside of harvesting and planting time should be prioritized in the future to meet the 2030 Sustainable Development Goal (SDG) target.

Trachoma is the leading cause of infectious loss of sight worldwide. The mass treatment with azithromycin has been used in the prevention and treatment of chlamydia trachomatis and is recognized as a potentially vital and important public health strategy for the control of trachoma disease and other co-infections. Oral azithromycin is easy to administer and offers a better resolution for controlling blinding trachoma for long periods. The proportion of azithromycin mass treatment coverage in the Goro district was lower than the WHO minimum target. Having better knowledge about the trachoma and azithromycin mass treatment and being educated were some of the factors positively affecting the uptake of the azithromycin mass treatment. Hearing serious adverse effects of the drug from other people and campaigns conducted during harvesting or seeding time were some factors negatively affecting the coverage of azithromycin mass treatment in the current study.

Trachoma

Trachoma is a neglected tropical disease caused by infection with conjunctival strains of Chlamydia trachomatis. It can result in blindness. Pathophysiologically, trachoma is a disease complex composed of two linked chronic processes: a recurrent, generally subclinical infectious-inflammatory disease that mostly affects children, and a non-communicable, cicatricial and, owing to trichiasis, eventually blinding disease that supervenes in some individuals later in life. At least 150 infection episodes over an individual's lifetime are needed to precipitate trichiasis; thus, opportunity exists for a just global health system to intervene to prevent trachomatous blindness. Trachoma is found at highest prevalence in the poorest communities of low-income countries, particularly in sub-Saharan Africa; in June 2021, 1.8 million people worldwide were going blind from the disease. Blindness attributable to trachoma can appear in communities many years after conjunctival C. trachomatis transmission has waned or ceased; therefore, the two linked disease processes require distinct clinical and public health responses. Surgery is offered to individuals with trichiasis and antibiotic mass drug administration and interventions to stimulate facial cleanliness and environmental improvement are designed to reduce infection prevalence and transmission. Together, these interventions comprise the SAFE strategy, which is achieving considerable success. Although much work remains, a continuing public health problem from trachoma in the year 2030 will be difficult for the world to excuse.

Effectiveness of azithromycin mass drug administration on trachoma: a systematic review

BACKGROUNDS

Azithromycin mass drug administration (MDA) is a key part of the strategy for controlling trachoma. This systematic review aimed to comprehensively summarize the present studies of azithromycin MDA on trachoma; provide an overview of the impact of azithromycin MDA on trachoma in different districts; and explore the possible methods to enhance the effectiveness of azithromycin MDA in hyperendemic districts.

METHODS

PubMed, Embase, the Cochrane Central Register of Controlled Trials, Web of Science, and ClinicalTrials.gov were searched up to February 2021 with no language restriction. Studies reporting the effect of azithromycin MDA on trachoma were included. Mathematical modeling studies, animal studies, case reports, and reviews were excluded. The trachomatous inflammation-follicular (TF) <5.0% was used to judge the effect of azithromycin MDA on eliminating trachoma as a public health problem. Two researchers independently conducted the selection process and risk of bias assessment.

RESULTS

A total of 1543 studies were screened, of which 67 studies including 13 cluster-randomized controlled trials and 54 non-randomized studies were included. The effect of azithromycin MDA on trachoma was closely related to the baseline prevalence in districts. For the districts with baseline prevalence between 5.0% and 9.9%, a single round of MDA achieved a TF <5.0%. For the districts with baseline between 10.0% and 29.9%, annual MDA for 3 to 5 years reduced TF <5.0%. However, for the districts with high level of baseline prevalence (TF >30.0%), especially with baseline TF >50.0%, annual MDA was unable to achieve the TF <5.0% even after 5 to 7 years of treatment. Quarterly MDA is more effective in controlling trachoma in these hyperendemic districts.

CONCLUSIONS

Azithromycin MDA for controlling trachoma depends on the baseline prevalence. The recommendation by the World Health Organization that annual MDA for 3 to 5 years in the districts with TF baseline >10.0% is not appropriate for all eligible districts.

Stopping azithromycin mass drug administration for trachoma: A systematic review

The World Health Organization (WHO) recommends continuing azithromycin mass drug administration (MDA) for trachoma until endemic regions drop below 5% prevalence of active trachoma in children aged 1–9 years. Azithromycin targets the ocular strains of Chlamydia trachomatis that cause trachoma. Regions with low prevalence of active trachoma may have little if any ocular chlamydia, and, thus, may not benefit from azithromycin treatment. Understanding what happens to active trachoma and ocular chlamydia prevalence after stopping azithromycin MDA may improve future treatment decisions. We systematically reviewed published evidence for community prevalence of both active trachoma and ocular chlamydia after cessation of azithromycin distribution. We searched electronic databases for all peer-reviewed studies published before May 2020 that included at least 2 post-MDA surveillance surveys of ocular chlamydia and/or the active trachoma marker, trachomatous inflammation–follicular (TF) prevalence. We assessed trends in the prevalence of both indicators over time after stopping azithromycin MDA. Of 140 identified studies, 21 met inclusion criteria and were used for qualitative synthesis. Post-MDA, we found a gradual increase in ocular chlamydia infection prevalence over time, while TF prevalence generally gradually declined. Ocular chlamydia infection may be a better measurement tool compared to TF for detecting trachoma recrudescence in communities after stopping azithromycin MDA. These findings may guide future trachoma treatment and surveillance efforts.

Trachoma, caused by repeated infections with ocular Chlamydia trachomatis, substantially contributes to the global burden of blindness. Community-wide distribution of the oral antibiotic azithromycin in trachoma endemic regions has contributed to significant decline in the prevalence of both ocular chlamydia infection and clinical findings of active trachoma. After azithromycin mass drug administration (MDA) stops, both ocular chlamydia and active trachoma can return. Our systematic review finds that ocular chlamydia infection may return to communities faster than signs of active trachoma, which may help better understand the utility of different trachoma indicators for post-MDA surveillance.

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

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.

Azithromycin Reduction to Reach Elimination of Trachoma (ARRET): study protocol for a cluster randomized trial of stopping mass azithromycin distribution for trachoma

Background

The World Health Organization (WHO) recommends annual mass azithromycin distribution until districts drop below 5% prevalence of trachomatous inflammation—follicular (TF). Districts with very low TF prevalence may have little or no transmission of the ocular strains of Chlamydia trachomatis that cause trachoma, and additional rounds of mass azithromycin distribution may not be useful. Here, we describe the protocol for a randomized controlled trial designed to evaluate whether mass azithromycin distribution can be stopped prior to the current WHO guidelines.

Methods

The Azithromycin Reduction to Reach Elimination of Trachoma (ARRET) study is a 1:1 community randomized non-inferiority trial designed to evaluate whether mass azithromycin distribution can be stopped in districts with baseline prevalence of TF under 20%. Communities in Maradi, Niger are randomized after baseline assessment either to continued annual mass azithromycin distribution or stopping annual azithromycin distribution over a 3-year period. We will compare the prevalence of ocular C. trachomatis (primary outcome), TF and other clinical signs of trachoma, and serologic markers of trachoma after 3 years. We hypothesize that stopping annual azithromycin distribution will be non-inferior to continued annual azithromycin distributions for all markers of trachoma prevalence and transmission.

Discussion

The results of this trial are anticipated to provide potentially guideline-changing evidence for when mass azithromycin distributions can be stopped in low TF prevalence areas.

Trial registration number

This study is registered at clinicaltrials.gov (NCT04185402). Registered December 4, 2019; prospectively registered pre-results.

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

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.

Antibiotics for trachoma

BACKGROUND

Trachoma is the world's leading infectious cause of blindness. In 1996, WHO launched the Alliance for the Global Elimination of Trachoma by the year 2020, based on the 'SAFE' strategy (surgery, antibiotics, facial cleanliness, and environmental improvement).

OBJECTIVES

To assess the evidence supporting the antibiotic arm of the SAFE strategy by assessing the effects of antibiotics on both active trachoma (primary objective), Chlamydia trachomatis infection of the conjunctiva, antibiotic resistance, and adverse effects (secondary objectives).

SEARCH METHODS

We searched relevant electronic databases and trials registers. The date of the last search was 4 January 2019.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that satisfied either of two criteria: (a) trials in which topical or oral administration of an antibiotic was compared to placebo or no treatment in people or communities with trachoma, (b) trials in which a topical antibiotic was compared with an oral antibiotic in people or communities with trachoma. We also included studies addressing different dosing strategies in the population.  DATA COLLECTION AND ANALYSIS: We used standard methods expected by Cochrane. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We identified 14 studies where individuals with trachoma were randomised and 12 cluster-randomised studies. Any antibiotic versus control (individuals)Nine studies (1961 participants) randomised individuals with trachoma to antibiotic or control (no treatment or placebo). All of these studies enrolled children and young people with active trachoma. The antibiotics used in these studies included topical (oxy)tetracycline (5 studies), doxycycline (2 studies), and sulfonamides (4 studies). Four studies had more than two study arms. In general these studies were poorly reported, and it was difficult to judge risk of bias.These studies provided low-certainty evidence that people with active trachoma treated with antibiotics experienced a reduction in active trachoma at three months (risk ratio (RR) 0.78, 95% confidence interval (CI) 0.69 to 0.89; 1961 people; 9 RCTs; I² = 73%) and 12 months (RR 0.74, 95% CI 0.55 to 1.00; 1035 people; 4 RCTs; I² = 90%). Low-certainty evidence was available for ocular infection at three months (RR 0.81, 95% CI 0.63 to 1.04; 297 people; 4 RCTs; I² = 0%) and 12 months (RR 0.25, 95% CI 0.08 to 0.78; 129 people; 1 RCT). None of these studies assessed antimicrobial resistance. In those studies that reported harms, no serious adverse effects were reported (low-certainty evidence).Oral versus topical antibiotics (individuals)Eight studies (1583 participants) compared oral and topical antibiotics. Only one study included people older than 21 years of age. Oral antibiotics included azithromycin (5 studies), sulfonamides (2 studies), and doxycycline (1 study). Topical antibiotics included (oxy)tetracycline (6 studies), azithromycin (1 study), and sulfonamide (1 study). These studies were poorly reported, and it was difficult to judge risk of bias.There was low-certainty evidence of little or no difference in effect between oral and topical antibiotics on active trachoma at three months (RR 0.97, 95% CI 0.81 to 1.16; 953 people; 6 RCTs; I² = 63%) and 12 months (RR 0.93, 95% CI 0.75 to 1.15; 886 people; 5 RCTs; I² = 56%). There was very low-certainty evidence for ocular infection at three or 12 months. Antimicrobial resistance was not assessed. In those studies that reported adverse effects, no serious adverse effects were reported; one study reported abdominal pain with azithromycin; one study reported a couple of cases of nausea with azithromycin; and one study reported three cases of reaction to sulfonamides (low-certainty evidence).Oral azithromycin versus control (communities)Four cluster-randomised studies compared antibiotic with no or delayed treatment. Data were available on active trachoma at 12 months from two studies but could not be pooled because of reporting differences. One study at low risk of bias found a reduced prevalence of active trachoma 12 months after a single dose of azithromycin in communities with a high prevalence of infection (RR 0.58, 95% CI 0.52 to 0.65; 1247 people). The other, lower quality, study in low-prevalence communities reported similar median prevalences of infection at 12 months: 9.3% in communities treated with azithromycin and 8.2% in untreated communities. We judged this moderate-certainty evidence for a reduction in active trachoma with treatment, downgrading one level for inconsistency between the two studies. Two studies reported ocular infection at 12 months and data could be pooled. There was a reduction in ocular infection (RR 0.36, 0.31 to 0.43; 2139 people) 12 months after mass treatment with a single dose compared with no treatment (moderate-certainty evidence). There was high-certainty evidence of an increased risk of resistance of Streptococcus pneumoniae, Staphylococcus aureus, and Escherichia coli to azithromycin, tetracycline, and clindamycin in communities treated with azithromycin, with approximately 5-fold risk ratios at 12 months. The evidence did not support increased resistance to penicillin or trimethoprim-sulfamethoxazole. None of the studies measured resistance to C trachomatis. No serious adverse events were reported. The main adverse effect noted for azithromycin (˜10%) was abdominal pain, vomiting, and nausea.Oral azithromycin versus topical tetracycline (communities)Three cluster-randomised studies compared oral azithromycin with topical tetracycline. The evidence was inconsistent for active trachoma and ocular infection at three and 12 months (low-certainty evidence) and was not pooled due to considerable heterogeneity. Antimicrobial resistance and adverse effects were not reported.Different dosing strategiesSix studies compared different strategies for dosing. There were: mass treatment at different dosing intervals; applying cessation or stopping rules to mass treatment; strategies to increase mass treatment coverage. There was no strong evidence to support any variation in the recommended annual mass treatment.

AUTHORS' CONCLUSIONS

Antibiotic treatment may reduce the risk of active trachoma and ocular infection in people infected with C trachomatis, compared to no treatment/placebo, but the size of the treatment effect in individuals is uncertain. Mass antibiotic treatment with single dose oral azithromycin reduces the prevalence of active trachoma and ocular infection in communities. There is no strong evidence to support any variation in the recommended periodicity of annual mass treatment. There is evidence of an increased risk of antibiotic resistance at 12 months in communities treated with antibiotics.

Enteropathogen antibody dynamics and force of infection among children in low-resource settings

Little is known about enteropathogen seroepidemiology among children in low-resource settings. We measured serological IgG responses to eight enteropathogens (Giardia intestinalis, Cryptosporidium parvum, Entamoeba histolytica, Salmonella enterica, enterotoxigenic Escherichia coli, Vibrio cholerae, Campylobacter jejuni, norovirus) in cohorts from Haiti, Kenya, and Tanzania. We studied antibody dynamics and force of infection across pathogens and cohorts. Enteropathogens shared common seroepidemiologic features that enabled between-pathogen comparisons of transmission. Overall, exposure was intense: for most pathogens the window of primary infection was <3 years old; for highest transmission pathogens primary infection occurred within the first year. Longitudinal profiles demonstrated significant IgG boosting and waning above seropositivity cutoffs, underscoring the value of longitudinal designs to estimate force of infection. Seroprevalence and force of infection were rank-preserving across pathogens, illustrating the measures provide similar information about transmission heterogeneity. Our findings suggest antibody response can be used to measure population-level transmission of diverse enteropathogens in serologic surveillance.

Diarrhea, which is caused by bacteria such as Salmonella or by viruses like norovirus, is the fourth leading cause of death among children worldwide, with children in low-resource settings being at highest risk. The pathogens that cause diarrhea spread when stool from infected people comes into contact with new hosts, for example, through inadequate sanitation or by drinking contaminated water. Currently, the best way to track these infections is to collect stool samples from people and test them for the presence of the pathogens. Unfortunately, this is costly and difficult to do on a large scale outside of clinical settings, making it hard to track the spread of diarrhea-causing pathogens.

The body produces antibodies – small proteins that can detect specific pathogens – in response to an infection. These antibodies help ward off future infections by the same pathogen, so if they are present in the blood, this indicates a current or previous infection. Scientists already collect blood samples to track malaria, HIV and vaccine-preventable diseases in low-resource settings. These samples could be tested more broadly to measure the levels of antibodies against diarrhea-causing pathogens.

Now, Arnold et al. have used blood samples collected from children in Haiti, Kenya, and Tanzania to measure antibody responses to 8 diarrhea-causing pathogens. The results showed that many children in these settings had been infected with all 8 pathogens before age three, and that all of the pathogens shared similar age-dependent patterns of antibody response. This finding enabled Arnold et al. to combine antibody measurements with statistical models to estimate each pathogen’s force of infection, that is, the rate at which susceptible individuals in the population become infected. This is a key step for epidemiologists to understand which pathogens cause the most infections in a population.

The experiments show that testing blood samples for antibodies could provide scientists with a new tool to track the transmission of diarrhea-causing pathogens in low-resource settings. This information could help public health officials design and test efforts to prevent diarrhea, for example, by improving water treatment or developing vaccines.