Reduction of trachoma in a sub-Saharan village in absence of a disease control programme

doi:10.1016/S0140-6736(97)01355-X

The Lancet

Volume 349, Issue 9064, 24 May 1997, Pages 1511-1512

https://doi.org/10.1016/S0140-6736(97)01355-X Get rights and content

Summary

Background

Trachoma is a leading cause of blindness in the developing world and is most prevalent among people who live in poor rural communities in arid locations.

Methods

We analysed the results of surveys of trachoma prevalence in Marakissa, a rural village in The Gambia. These surveys were undertaken in 1959, by the Medical Research Council, and in 1987 and 1996 by the Gambian National Eye Care Programme.

Findings

During this 37-year period, the prevalence of active inflammatory trachoma among children aged 0–9 years fell from 65·7 cases per 100 children in 1959 to 2·4 cases per 100 children in 1996. The prevalence also fell dramatically among people of 10–19 years (52·5 to 1·4 per 100) and among people of 20 years and older (36·7 to 0 cases per 100).

Interpretation

The dramatic fall in disease occurrence was paralleled by improvements in sanitation, water supply, education, and access to health care in the village. Of particular importance is that the decline in trachoma occurred without any trachoma-specific intervention.

Introduction

Trachoma, an eye infection caused by Chlamydia trachomatis, is the major preventable cause of blindness in the world. Current estimates suggest that about 150 million people have active infection, most of whom are children. Transmission occurs by several routes, including flies that infect the eyes directly, person-to-person from clothing used to wipe children's faces, and by hand-toface contact.

Important risk factors for trachoma include lack of facial cleanliness, poor access to water supplies, lack of latrines, and a high number of files.1, 2 The disease is known to occur within households and family groups. The prevalence is disproportionately high in women and children, and people in poor rural communities.

Improvement in standards of living eradicated trachoma in western countries by the early part of this century. In other regions, trachoma-specific control programmes led to large reductions in the prevalence of the disease. By contrast, in most sub-Saharan countries, which do not have the advantage of good living standards or effective trachoma-control programmes, trachoma continues to be a major public-health concern. The Gambia has, however, seen a small but definite improvement in socioeconomic standards.

We present longitudinal data on the prevalence of active inflammatory trachoma in one Gambian village over a 37-year period. Marakissa is a small rural village with a current population of around 1000 people and is typical of villages in The Gambia. The villages are divided into family compounds, which each consist of a fenced-in area, with the living quarters and domestic livestock at one end and the vegetable garden and fruit trees in the rest of the space. The village focal point is the bantaba, a large tree under which community meetings are held, and decisions made.

Section snippets

Methods

The first trachoma survey of Marakissa village was done in 1959 by the Medical Research Council.³ The village was surveyed again in 1987,⁴ and in 1996 by the Gambian National Eye Care Programme. In each survey the eyes of every person in the village were examined with a binocular loupe to find the prevalence and clinical stages of trachoma. Trachoma was graded according to the classification system that was recommended at the time of each survey. In 1959, an adaptation of the system developed

Results

The Table gives age-specific prevalence of active inflammatory trachoma from the 1959, 1987, and 1996 surveys. There has been a dramatic reduction in the prevalence of active inflammatory trachoma during the past four decades. Among children aged 0–9 years, two in every three children had active infection in 1959, whereas by 1996 the proportion had fallen to two in every 100 children. Dramatic falls in prevalence also occurred in the older age-groups.

Entropion (inversion of the eyelid margin)

Discussion

Marakissa looks like any other Gambian village. In common with the rest of The Gambia, there have been some improvements in socioeconomic standards. For example, in 1959, the access road was only a bush track, which was impassable during the rainy season. Today there is a good all-weather road, and four-wheel-drive vehicles, pick-up trucks, and various other “bush taxis” pass through the village and provide regular transport to the neighbouring town Brikama. The number of houses with corrugated

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Hygiene factors and increased risk of trachoma in central Tanzania
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Latrine ownership as a protective factor in inflammatory trachoma in Egypt
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S Sowa et al.
Trachoma and allied infections in a Gambian village. Medical Research Council, Special Report Series no 308
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The distribution of the prevalence of ocular chlamydial infection in communities where trachoma is disappearing
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Citation Excerpt :
Mass antibiotics distributions have proven effective in cluster-randomized trials, and have so far been well tolerated (Schachter et al., 1999; Chidambaram et al., 2006; House et al., 2009). Trachoma has been disappearing in some areas, even in the absence of a dedicated trachoma program (Hoechsmann et al., 2001; Jha et al., 2002; Dolin et al., 1997). This report suggests that if efforts are continued, infection will eventually disappear in previously hyper-endemic areas of Ethiopia.
Mathematical models predict that the prevalence of infection in different communities where an infectious disease is disappearing should approach a geometric distribution. Trachoma programs offer an opportunity to test this hypothesis, as the World Health Organization (WHO) has targeted trachoma to be eliminated as a public health concern by the year 2020. We assess the distribution of the community prevalence of childhood ocular chlamydia infection from periodic, cross-sectional surveys in two areas of Ethiopia. These surveys were taken in a controlled setting, where infection was documented to be disappearing over time. For both sets of surveys, the geometric distribution had the most parsimonious fit of the distributions tested, and goodness-of-fit testing was consistent with the prevalence of each community being drawn from a geometric distribution. When infection is disappearing, the single sufficient parameter describing a geometric distribution captures much of the distributional information found from examining every community. The relatively heavy tail of the geometric suggests that the presence of an occasional high-prevalence community is to be expected, and does not necessarily reflect a transmission hot spot or program failure. A single cross-sectional survey can reveal which direction a program is heading. A geometric distribution of the prevalence of infection across communities may be an encouraging sign, consistent with a disease on its way to eradication.
Association of community antibiotic consumption with clinically active trachoma in rural Ethiopia
2011, International Health
Citation Excerpt :
Components of the WHO's SAFE strategy, including mass antibiotic distributions, facial hygiene promotion, and environmental improvements, are effective in reducing the burden of ocular chlamydial infection and trachoma.2 Even in the absence of a designated trachoma control program, reductions in trachoma prevalence have been reported in some areas of Africa and Asia in recent years.3–5 This secular trend has been attributed to inherent benefits of economic development, including improved hygiene and sanitation.
Community antibiotic utilization and its relationship with trachoma has been poorly characterized in areas with endemic trachoma. A survey of all drug-dispensing facilities in an area of rural Ethiopia was conducted. Antibiotic use was calculated using both retrospective and prospective methodology, and expressed as defined daily doses (DDDs). Overall antibiotic consumption estimates ranged from 2.91 to 3.07 DDDs per 1000 person days. Macrolide antibiotics accounted for 0.01 to 0.02 DDDs per 1000 person days. Each additional DDD of antibiotic use per 1000 person days was associated with a 15.0% (95% CI -19.7 to -10.3) decrease in the prevalence of clinically active trachoma among children under 10 years of age after adjusting for age, gender, altitude and the distance to nearest town. Increased background community antibiotic use may therefore be an aspect of socioeconomic development that can partially explain why trachoma prevalence has decreased in some areas in the absence of a trachoma program. The low volume of macrolide consumption in this area suggests that selection for nasopharyngeal pneumococcal macrolide resistance after mass azithromycin treatments likely has little clinical significance.
Relationship between distance to social gathering facilities and risk of trachoma for households in rural Tanzanian communities
2011, Social Science and Medicine
Citation Excerpt :
This debilitating disease is caused by the bacterium Chlamydia trachomatis, which is transmitted directly and mechanically by eye-seeking flies that breed in human feces (Mabey, Soloman, & Foster, 2003). Prevention and eventual elimination is possible through safe hygiene behavior and improved environmental sanitation (Allen & Semba, 2002; Dolin, Faal, Johnson, Minassian, & Sowa, 1997; Jha, Chaudary, Bhatta, Miao, & Baynor, 2002). Motivating such hygiene and sanitation modifications, especially in the most at-risk households, is critical for achieving and sustaining the 2020 global goal of eliminating blinding trachoma (Mariotti, Pararajaseqaram, & Resnikoff, 2003; Montgomery, 2006; West, 2003).
Few studies have examined the physical isolation of households with trachoma cases. Thus, in this study, we sought to examine the association between household isolation, as measured by distance to social gathering facilities, and risk of trachoma. We hypothesized that households located closer to such facilities would have a decreased risk of trachoma, due to a variety of social, economic, and cultural reasons. To test this hypothesis we conducted a case-control study of 668 households (93 cases, 575 controls) in eight villages in Kongwa District, Tanzania, in 2007. Case households were defined as having a child aged 1–5 years with clinical signs of trachoma. Distance of household’s place of residence to three main social gathering facilities — bars/cafés, religious establishments, and commercial/government center — was measured with a portable geographic positioning system. Multiple logistic regression analyses, which controlled for potential confounders and accounted for clustering, demonstrated increased risk of trachoma with increasing distance to social gathering facilities. Compared with distances of ≤700 m, odds of trachoma were approximately two-fold higher for households living >1400 m from bars/cafés and from religious establishments, suggesting increased risk of trachoma for households at the fringes of communities. Targeting these isolated households with special programming along with dissemination through trusted social gathering facilities may improve effectiveness of current prevention efforts.
Comparison of annual versus twice-yearly mass azithromycin treatment for hyperendemic trachoma in Ethiopia: A cluster-randomised trial
2012, The Lancet
Citation Excerpt :
To the extent that the substantial (and expected) drops in infection prevalence we recorded were partly attributable to effects other than antibiotic distribution, our results would overestimate the decrease in prevalence after treatment when applied to a region in which no such secular trend was present. Such trends have been reported in other settings,39–42 although we did not note a secular trend in 12 untreated neighbouring control state teams during the first 12 months of our study. The prevalence of infection in these untreated state teams at 12 months was 45·6 % (95% CI 36·7 to 54·5), similar to that identified in our study state teams at baseline.13
In trachoma control programmes, azithromycin is distributed to treat the strains of chlamydia that cause ocular disease. We aimed to compare the effect of annual versus twice-yearly distribution of azithromycin on infection with these strains.
We did a cluster-randomised trial in 24 subdistricts in northern Ethiopia, which we randomly assigned to receive annual or twice-yearly treatment for all residents of all ages. Random assignment was done with the RANDOM and SORT functions of Microsoft Excel. All individuals were offered their assigned treatment of a single, directly observed, oral dose of azithromycin. A 6 week course of topical 1% tetracycline ointment, applied twice daily to both eyes but not directly observed, was offered as an alternative to azithromycin in patients younger than 12 months, and in patients with self-reported pregnancy, with allergy, or who refused azithromycin. Our primary, prespecified outcome was the prevalence of ocular chlamydial infection in a random sample of children aged 0–9 years at baseline and every 6 months for a total of 42 months within sentinel villages. Our analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00322972.
Antibiotic coverage of children aged 1–9 years was greater than 80% (range 80·9 to 93·0) at all study visits. In the groups treated annually, the prevalence of infection in children aged 0–9 years was reduced from a mean 41·9% (95% CI 31·5 to 52·2) at baseline to 1·9% (0·3 to 3·5) at 42 months. In the groups treated twice yearly, the prevalence of infection was reduced from a mean 38·3% (29·0 to 47·6) at baseline to 3·2 % (0·0 to 6·5) at 42 months. The prevalence of ocular chlamydial infection in children aged 0–9 years in groups treated annually was not different from that of the groups treated twice yearly at 18, 30, and 42 months (pooled regression p>0·99, 95 % CI −0·06 to 0·06). The mean elimination time in the twice-yearly treatment group was 7·5 months earlier (2·3 to 17·3) than that of the annual group (p=0·10, Cox proportional hazards model).
After 42 months of treatment, the prevalence of ocular infection with chlamydia was similar in the groups treated annually and twice yearly. However, elimination of infection might have been more rapid in the groups of villages that received treatment twice yearly.
National Institutes of Health (NEI U10 EY016214).
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ArticlesReduction of trachoma in a sub-Saharan village in absence of a disease control programme

Summary

Background

Methods

Findings

Interpretation

Introduction

Section snippets

Methods

Results

Discussion

Hygiene factors and increased risk of trachoma in central Tanzania

Arch Ophthalmol

Latrine ownership as a protective factor in inflammatory trachoma in Egypt

Br J Ophthalmol

Trachoma and allied infections in a Gambian village. Medical Research Council, Special Report Series no 308

Articles
Reduction of trachoma in a sub-Saharan village in absence of a disease control programme