Muluken Melese

Indirect costs associated with accessing eye care services as a barrier to service use in Ethiopia

Background  The prevalence of blindness and visual impairment are high in Ethiopia and use of services is limited. Determining the barriers to use of eye care services is critical for planning strategies to prevent blindness.

Comparison of Annual and Biannual Mass Antibiotic Administration for Elimination of Infectious Trachoma

CONTEXT Treatment recommendations assume that repeated mass antibiotic distributions can control, but not eradicate or even locally eliminate, the ocular strains of chlamydia that cause trachoma. Elimination may be an important end point because of concern that infection will return to communities that have lost immunity to chlamydia after antibiotics are discontinued. OBJECTIVE To determine whether biannual treatment can eliminate ocular chlamydial infection from preschool children and to compare results with the World Health Organization-recommended annual treatment. DESIGN, SETTING, AND PARTICIPANTS A cluster-randomized clinical trial of biannual vs annual mass azithromycin administrations to all residents of 16 rural villages in the Gurage Zone, Ethiopia, from March 2003 to April 2005. INTERVENTIONS At scheduled treatments, all individuals aged 1 year or older were offered a single dose of oral azithromycin either annually or biannually. MAIN OUTCOME MEASURE Village prevalence of ocular chlamydial infection and presence of elimination at 24 months in preschool children determined by polymerase chain reaction, correcting for baseline prevalence. Antibiotic treatments were performed after sample collections. RESULTS Overall, 14,897 of 16,403 eligible individuals (90.8%) received their scheduled treatment. In the villages in which residents were treated annually, the prevalence of infection in preschool children was reduced from a mean of 42.6% (range, 14.7%-56.4%) to 6.8% (range, 0.0%-22.0%) at 24 months. In the villages in which residents were treated biannually, infection was reduced from 31.6% pretreatment (range, 6.1%-48.6%) to 0.9% (range, 0.0%-4.8%) at 24 months. Biannual treatment was associated with a lower prevalence at 24 months (P = .03, adjusting for baseline prevalence). At 24 months, no infection could be identified in 6 of 8 of those treated biannually and in 1 of 8 of those treated annually (P = .049, adjusting for baseline prevalence). CONCLUSION Local elimination of ocular chlamydial infection appears feasible even in the most severely affected areas, although it may require biannual mass antibiotic distributions at a high coverage level. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00221364.

A rationale for continuing mass antibiotic distributions for trachoma.

BackgroundThe World Health Organization recommends periodic mass antibiotic distributions to reduce the ocular strains of chlamydia that cause trachoma, the worlds leading cause of infectious blindness. Their stated goal is to control infection, not to completely eliminate it. A single mass distribution can dramatically reduce the prevalence of infection. However, if infection is not eliminated in every individual in the community, it may gradually return back into the community, so often repeated treatments are necessary. Since public health groups are reluctant to distribute antibiotics indefinitely, we are still in need of a proven long-term rationale. Here we use mathematical models to demonstrate that repeated antibiotic distributions can eliminate infection in a reasonable time period.MethodsWe fit parameters of a stochastic epidemiological transmission model to data collected before and 6 months after a mass antibiotic distribution in a region of Ethiopia that is one of the most severely affected areas in the world. We validate the model by comparing our predicted results to Ethiopian data which was collected biannually for two years past the initial mass antibiotic distribution. We use the model to simulate the effect of different treatment programs in terms of local elimination of infection.ResultsSimulations show that the average prevalence of infection across all villages progressively decreases after each treatment, as long as the frequency and coverage of antibiotics are high enough. Infection can be eliminated in more villages with each round of treatment. However, in the communities where infection is not eliminated, it returns to the same average level, forming the same stationary distribution. This phenomenon is also seen in subsequent epidemiological data from Ethiopia. Simulations suggest that a biannual treatment plan implemented for 5 years will lead to elimination in 95% of all villages.ConclusionLocal elimination from a community is theoretically possible, even in the most severely infected communities. However, elimination from larger areas may require repeated biannual treatments and prevention of re-introduction from outside to treated areas.

Reduction and return of infectious trachoma in severely affected communities in Ethiopia.

Background Antibiotics are a major tool in the WHOs trachoma control program. Even a single mass distribution reduces the prevalence of the ocular chlamydia that causes trachoma. Unfortunately, infection returns after a single treatment, at least in severely affected areas. Here, we test whether additional scheduled treatments further reduce infection, and whether infection returns after distributions are discontinued. Methods Sixteen communities in Ethiopia were randomly selected. Ocular chlamydial infection in 1- to 5-year-old children was monitored over four biannual azithromycin distributions and for 24 months after the last treatment. Findings The average prevalence of infection in 1- to 5-year-old children was reduced from 63.5% pre-treatment to 11.5% six months after the first distribution (P<0.0001). It further decreased to 2.6% six months after the fourth and final treatment (P = 0.0004). In the next 18 months, infection returned to 25.2%, a significant increase from six months after the last treatment (P = 0.008), but still far lower than baseline (P<0.0001). Although the prevalence of infection in any particular village fluctuated, the mean prevalence of the 16 villages steadily decreased with each treatment and steadily returned after treatments were discontinued. Conclusion In some of the most severely affected communities ever studied, we demonstrate that repeated mass oral azithromycin distributions progressively reduce ocular chlamydial infection in a community, as long as these distributions are given frequently enough and at a high enough coverage. However, infection returns into the communities after the last treatment. Sustainable changes or complete local elimination of infection will be necessary. Trial Registration ClinicalTrials.gov NCT00221364

How reliable is the clinical exam in detecting ocular chlamydial infection

purpose To describe the relationship between the clinical exam for trachoma and the polymerase chain reaction (PCR) for ocular chlamydia. methods One hundred children in a trachoma-endemic area of Ethiopia were examined three times and swabbed twice for PCR analysis. The assays were compared, and an analysis of the variance between exam and PCR was performed. results Inter-examiner agreement was 0.57 (Cohens κ), inter-PCR agreement 0.98, and agreement between examiner and PCR, 0.26–0.34. The positive predictive value of the exam in identifying infection was 66%. Inter-examiner variance accounted for 30% of the total variance between the exam and PCR, with the remainder presumably due to an underlying difference in what the exam and PCR measure. conclusions Despite modest inter-grader reliability and correlation with evidence of infection, the clinical exam is widely used due to its convenience and low cost. Efforts to make laboratory tests for ocular Chlamydia trachomatismore affordable would be useful.

Pesky trachoma suspect finally caught

Aim: Face seeking flies have long been thought to transmit Chlamydia trachomatis, the causative agent of trachoma, but this has never been proven. The four criteria proposed by Barnett, previously used to incriminate other arthropods suspected of transmitting disease, were examined. One of these criteria remains unmet: the repeated demonstration of the presence of C trachomatis on flies. The authors used polymerase chain reaction (PCR) to look for the presence of C trachomatis DNA on flies in the Gurage Zone of Ethiopia. Methods: Using sticky paper, one fly was collected from the face of each of 103 children aged 1–10 years. The piece of fly paper to which the fly was attached was cut out, followed by the collection of an empty piece from an arbitrary area of the fly paper, which served as control. Roche Amplicor PCR kits were used to detect C trachomatis DNA. Results: Evidence of C trachomatis by PCR was found on 15 of 103 flies versus 0 of 103 controls (p = 0.0001). Conclusion: These results meet the final criterion needed to incriminate flies as a vector of trachoma. However, interventional studies will be needed to show the importance of fly control.

How Reliable Are Tests for Trachoma?—A Latent Class Approach

PURPOSE Tests for ocular Chlamydia trachomatis have not been well characterized, because there is no gold standard test. Latent class analysis (LCA) was performed to estimate the sensitivity and specificity of laboratory and clinical tests for trachoma in the absence of a gold standard. METHODS Individual data from pretreatment, hyperendemic areas in Ethiopia were used. A clustered LCA was performed for three diagnostic tests: PCR and WHO simplified criteria grades of follicular trachoma (TF) and intense trachomatous inflammation (TI). RESULTS Data from 2111 subjects in 40 villages were available. TF was estimated to be 87.3% (95% CI, 83.3-90.1) sensitive and 36.6% (95% CI, 23.6-40.3) specific; TI was estimated to be 53.6% (95% CI, 46.1-88.0) sensitive and 88.3% (95% CI, 83.3-92.0) specific, and PCR was estimated to be 87.5% (95% CI, 79.9-97.2) sensitive and 100% (95% CI 69.3-100) specific. CONCLUSIONS LCA allows for an estimate of test characteristics without prior assumption of their performance. TF and TI were found to act in a complementary manner: TF is a sensitive test and TI is a specific test. PCR is highly specific but lacks sensitivity. The performance of these tests may be due to the time course of ocular chlamydial infection, and for this reason, results may differ in areas of low prevalence or recent mass treatment (ClinicalTrials.gov number, NCT00221364).

Clinical Activity and Polymerase Chain Reaction Evidence of Chlamydial Infection after Repeated Mass Antibiotic Treatments for Trachoma

It is unclear how the prevalence of clinically active trachoma correlates with the prevalence of ocular chlamydial infection at the community level. In 24 villages from a cluster-randomized clinical trial of mass azithromycin distributions in Ethiopia, the correlation between the prevalence of clinical activity (on examination) and chlamydial infection (by polymerase chain reaction) was moderately strong before mass antibiotic treatments (Pearsons correlation coefficient r = 0.75, 95% confidence interval [CI] = 0.52-0.87), but decreased at each time point during four biannual treatments (at 24 months, r = 0.15, 95% CI = -0.14-0.41). One year after the final treatment, the correlation coefficient had increased, but not to the pre-treatment level (r = 0.55, 95% CI = 0.30-0.73). In a region with hyperendemic trachoma, conjunctival examination was a useful indicator of the prevalence of chlamydial infection before treatments, less useful during mass treatments, but regained utility by one year after treatments had stopped.

Slow Resolution of Clinically Active Trachoma Following Successful Mass Antibiotic Treatments

Trachoma, caused by infection with ocular strains of chlamydia, is the leading infectious cause of blindness worldwide. The World Health Organization recommends that in districts where the prevalence of clinically active trachoma exceeds 10% in children aged 1 to 9 years, communities should receive 3 annual mass antibiotic distributions followed by clinical reassessment; any communities with persistent trachoma should continue receiving annual mass antibiotic treatments until the prevalence of clinically active trachoma in children aged 1 to 9 years falls below 5% 1. Although trachoma treatment decisions are based on the prevalence of clinically active trachoma, it is unclear how quickly the clinical signs of trachoma resolve once infection has been cleared, especially in areas with severe trachoma. We recently performed a series of cluster-randomized clinical trials for trachoma in an area of Ethiopia with hyperendemic trachoma. In these trials, infection was brought to a low level in 24 villages randomized to receive mass azithromycin treatments every 6 months. This provided an opportunity to determine the rate of resolution of the clinical signs of trachoma given little to no chlamydial reinfection.

The association between epilation and corneal opacity among eyes with trachomatous trichiasis

Aim: To examine the association between epilation and corneal opacity (CO) among trichiasis patients presenting for surgery. Methods: Cross sectional data from the STAR trial were utilised. Patients presenting for trichiasis surgery in Wolayta Zone, Ethiopia, were evaluated for current trichiasis status. Number of inturned lashes, evidence of epilation, level of entropion, trichiasis duration, and CO were collected. The primary outcome was prevalence of CO, stratified by entropion and epilation status. Results: Approximately 10% of eyes with mild entropion had CO, regardless of epilation status. Among eyes with moderate entropion, epilated eyes were less likely to have CO than non-epilated eyes (21% v 34% p = 0.002). The same association was seen in eyes with severe entropion: 43% of epilated eyes while 74% of non-epilated eyes had CO (p<0.0001). Presence of CO increased with age. Adjusted models showed a protective effect of epilation in eyes with moderate or severe entropion (OR: 0.51; 95% CI: 0.32 to 0.83 and OR: 0.24; 95% CI: 0.13 to 0.45, respectively). Among eyes with mild entropion there was no difference in the prevalence of CO comparing eyes that were epilated with those that were not epilated. Conclusion: Entropion was the most significant predictor of CO. Cross sectional associations suggest that epilation may not be helpful for eyes with mild entropion, but may offer protection against CO in eyes with moderate to severe entropion. Epilation should not be a substitute for trichiasis surgery, however, as 43% of eyes with severe entropion that were epilated still had CO.