Review of the publications of the Nigeria national blindness survey: methodology, prevalence, causes of blindness and visual impairment and outcome of cataract surgery.

This is a review of the major publications from the Nigeria national blindness survey in order to highlight major findings and challenges of eye care in Nigeria. The review summarizes methodology and key findings. Survey publications on methodology, prevalence and causes of visual impairment and outcome of cataract surgery were retrieved, reviewed and relevant data extracted, reported and discussed. The study was the largest and more detailed eye survey in Nigeria (15,375 people 40 years and older recruited). Participants had detailed eye examination including visual acuity, autorefractokeratometry, A- scan biometry, visual field and basic eye examination. Cause(s) of visual impairment in each eye using WHO algorithm was determined among participants with vision < 6/12. Some of the participants also had qualitative questions on barriers to uptake of services, quality of life and visual function. Major highlights of the results as contained in the publications include a high prevalence of blindness with 4.2% (95% CI: 3.8-4.6%;),of the study population having blindness (using presenting vision (PVA)) even with best correction the prevalence was 3.4% (95% CI: 3.0-3.8%. The prevalence of SVI using PVA was 1.5% (95% CI: 1.3-1.7%).and with best correction 0.8% (95% CI: 0.7-1.0%). Blindness varied by age groups, sex, literacy level and geopolitical zone. Furthermore, 84% of blindness was due to avoidable causes with cataract responsible for 43% of blindness, glaucoma 16.7%, uncorrected aphakia 8.4% and corneal opacity 7.9%. Of the total 538 eyes that had cataract surgery procedures, 42.7% had couching and the remaining had cataract surgery, but only 41.4% of cataract operated eyes had IOL surgery. Outcome of cataract surgery was good at presentation for only 30.8% of eyes (84 eyes) which improved to 56.8% with correction. The possible remedy for the high burden of needless blindness and harmful eye health practices in Nigeria are discussed.

Uniocular Blindness among Children in the Gambia

Background: Uniocular blindness in children though not uncommon has not been given prominence; as emphasis is placed on binocular blindness.Aim: To determine the common causes of uniocular blindness in children; and to suggest strategies for prevention.Methods: A prospective study involving children seen at the Eye Clinic of the Royal Victoria Hospital; The Gambia was undertaken; from the 1st December 1999 to 30th June 2000. All newly diagnosed cases of children who attended the clinic and were blind in one eye during the period of the study were included. A history was taken; visualacuity using age specific methods and ocular examinations were carried out. When necessary an examination under anaesthesia was performed.Results: Out of 470 children; 45(10) had uniocular blindness; 39(86) were aged 6-15years. The male - female ratio was 4:1. Common causes were trauma 28(62); uveitis 4(9); and corneal ulcer 3(7) . Others included congenital cataract; glaucoma and retinoblastoma.Conclusion: The commonest cause of uniocular blindness was ocular trauma. Focus should be directed towards the prevention; early referral and appropriate treatment of ocular trauma in children. Strategies for the prevention of childhood blindness would also be applicable to uniocular blindness in The Gambia

A randomised controlled trial of azithromycin following surgery for trachomatous trichiasis in the Gambia.

BACKGROUND/AIM: Trachomatous trichiasis frequently returns following surgery. Several factors may promote recurrence: preoperative disease severity, surgeon ability, surgical procedure, healing responses, and infection. This study investigates whether enhanced control of infection, both of Chlamydia trachomatis and other bacteria, with azithromycin can improve surgical outcome in a trachoma control programme. METHODS: Individuals with trachomatous trichiasis were examined and operated. After surgery patients were randomised to the azithromycin or control group. The azithromycin group and children in their household were given a dose of azithromycin. Antibiotic treatment was repeated at 6 months. All patients were reassessed at 6 months and 12 months. Samples were collected for C trachomatis polymerase chain reaction and general microbiology at each examination. RESULTS: 451 patients were enrolled. 426 (94%) were reassessed at 1 year, of whom 176 (41.3%) had one or more lashes touching the eye and 84 (19.7%) had five or more lashes. There was no difference in trichiasis recurrence between the azithromycin and control group. Recurrent trichiasis was significantly associated with more severe preoperative trichiasis, bacterial infection, and severe conjunctival inflammation at 12 months. Significant variability in outcome was found between surgeons. Visual acuity and symptoms significantly improved following surgery. CONCLUSION: In this setting, with a low prevalence of active trachoma, azithromycin did not improve the outcome of trichiasis surgery conducted by a trachoma control programme. Audit of trichiasis surgery should be routine.

Types of Glaucoma and recent trends applied in treatment: Observations from a Glaucoma Training Workshop in the Gambia.

OBJECTIVES: To determine types of glaucoma seen and the recent trends applied in treatment, a retrospective non-comparative case-series study was conducted in the Eye Unit of the Royal Victoria Hospital, Banjul, The Gambia. METHODS: The records of the 88 patients(145 eyes) seen during the glaucoma training workshop(organised by Prof.James Standefer, a clinical ophthalmologist from Minneapolis, U.S.A.) which held between 3rd and 14th of September, 2001, were analysed for types of glaucoma and treatment given. All but one patient who was a baby underwent the following tests: visual acuity measurement using the illiterate E-Chart with multiple optotypes; tonometry using the Schiotz tonometer with the 5.5g weight; oblique flashlight test; Van Herrick's estimation of the angle depth; pupillary reactions to light; Slitlamp biomicroscopy; gonioscopy using the 4-mirror pressure gonioprism; fundoscopy using the +78D Volk lens and confrontational visual field analysis. RESULTS: 27 eyes did not have definite glaucoma. Out of the remaining 118 eyes, 65(55.08%) had POAG;17(14.41%)ACG out of which 8 were CACG and 2 acute ACG. 8 eyes had pseudoexfoliation of the lens capsule with or without glaucoma. In the frail and elderly, guttae Timoptol 0.5% was given once daily. 27 eyes had trabeculectomy; all were with releasable sutures and intraoperative application of 5-Fluorouracil. 3 eyes had laser trabeculoplasty and 5, diode laser transscleral cyclophotocoagulation. CONCLUSIONS: POAG was the commonest type of glaucoma seen. Pseudoexfoliation of the lens capsule with or without glaucoma and ACG are not very rare in The Gambia. In the frail and elderly, guttae Timoptol 0.5% was given once daily and none at all in painless glaucoma-blind eyes. Trabeculectomy with releasable sutures and intraoperative application of 5-FU has a very satisfactory pressure-lowering effect. KEYWORDS: glaucoma; treatment; the Gambia.

Long term outcome of trichiasis surgery in the Gambia.

BACKGROUND: Trichiasis surgery is believed to reduce the risk of losing vision from trachoma. There are limited data on the long term outcome of surgery and its effect on vision and corneal opacification. Similarly, the determinants of failure are not well understood. METHODS: A cohort of people in the Gambia who had undergone surgery for trachomatous trichiasis 3-4 years earlier was re-assessed. They were examined clinically and the conjunctiva was sampled for Chlamydia trachomatis polymerase chain reaction (PCR) and general bacterial culture. RESULTS: In total, 141/162 people were re-examined. Recurrent trichiasis was found in 89/214 (41.6%) operated eyes and 52 (24.3%) eyes had five or more lashes touching the globe. Corneal opacification improved in 36 of 78 previously affected eyes. There was a general deterioration in visual acuity between surgery and follow up, which was greater if new corneal opacification developed or trichiasis returned. Recurrent trichiasis was associated with severe conjunctival inflammation and bacterial infection. C trachomatis was detected in only one individual. CONCLUSIONS: Recurrent trichiasis following surgery is a common potentially sight threatening problem. Some improvement in the cornea can occur following surgery and the rate of visual loss tended to be less in those without recurrent trichiasis. The role of conjunctival inflammation and bacterial infection needs to be investigated further. Follow up of patients is advised to identify individuals needing additional surgical treatment.

Non-trachomatous corneal opacities in the Gambia--aetiology and visual burden.

AIMS: National blindness surveys conducted in the Gambia in 1986 and 1996 showed an increase in blindness and visual impairment from non-trachomatous opacity. This study aimed to investigate the aetiology of these opacities and to assess the resulting visual burden. METHODS: A population-based, randomised blindness survey was conducted in the Gambia in 1996. Patients with visual impairment or blindness were examined by an ophthalmologist with a slit lamp. Causes of corneal opacity were determined as accurately as possible by clinical history and examination. RESULTS: A total of 154 patients with non trachomatous corneal opacity were examined of whom 39 had bilateral opacities and 115, unilateral. Causes included corneal infection, measles/vitamin A deficiency, harmful traditional practices and trauma (unilateral scarring). Overall, corneal pathology alone was responsible for bilateral visual impairment or blindness in 19 (12%) patients and unilateral visual impairment or blindness in 88 (57%) patients. Those patients with bilateral visual impairment or blindness (mean age 59, SD) were older (P= 0.003) than others (mean age 44, SD = 20). The use of harmful traditional eye practices was associated with bilateral corneal blindness or visual impairment (RR = 2.63, 95% CI 1.11-6.21, P = 0.04). Although none of the corneal scars reported here were attributed to trachoma, in patients over the age of 45, the prevalence of trachomatous conjunctival scarring in this group was 38.8% compared to 19.4% of the whole nationwide sample. DISCUSSION: Strategies for the prevention (including the quest for cheaper anti-microbial drugs and co-operation with traditional healers) and surgical treatment of these corneal opacities are discussed.

Longitudinal study of trachomatous trichiasis in the Gambia.

AIM: Investigation of the natural history of trachomatous trichiasis in the Gambia and of the outcome of self epilation and surgery for the condition. METHODS: A 1 year longitudinal study of 190 subjects with trichiasis was performed. Major trichiasis cases (five lashes or more) were referred for surgery and minor trichiasis cases were advised to epilate. Outcome measures included progression of trichiasis and corneal scarring; attendance for and results of surgery. RESULTS: 34 of 148 (23%, 95% CI 16 to 31) subjects with major trichiasis attended for surgery over the year. Progression from minor to major trichiasis occurred in 18 of 55 subjects (33%, 95% CI 21 to 47). Progression of corneal scarring occurred in 60 of 167 patients (36%, 95% CI 29 to 44). Clinically active trachoma and conjunctival bacterial isolation predicted progression of corneal opacity. Surgery was successful in 39 of 54 (72%) eyes. CONCLUSIONS: Despite the overall decline in trachoma in the Gambia, patients with both minor and major trichiasis remain at risk of developing corneal opacity. Active trachomatous inflammation and additional infection with bacteria may accelerate this process. Antibiotic treatment for trichiasis patients (in addition to surgery) should be investigated. Surgery for minor trichiasis may be indicated. Regular audit of surgical results is necessary with retraining where needed.

Natural history of trachomatous scarring in The Gambia: results of a 12-year longitudinal follow-up.

PURPOSE: The sight-threatening complications of trachoma are trichiasis and corneal opacity, and these remain the world's most common cause of preventable blindness. The aim of the study was to investigate the rate of progression of trachomatous conjunctival scarring to trichiasis and corneal opacity and to investigate risk factors for such progression. DESIGN: A 12-year, longitudinal study of the incidence and risk factors for the development of trichiasis and corneal opacity in a cohort of patients initially identified with trachomatous scarring in The Gambia. PARTICIPANTS: Six hundred thirty-nine subjects with some degree of trachomatous scarring were identified from the 1986 survey, and attempts were made to trace all these subjects. METHODS: Successfully traced subjects were interviewed, examined, and graded for trachoma. MAIN OUTCOME MEASURES: (1) Twelve-year rates of progression. (2) Risk factors for progression of disease. RESULTS: Three hundred twenty-six of six hundred thirty-nine (51%) subjects were traced and examined, 108 (17%) had died, and 205 (32%) were lost to follow-up. After 12 years, 6.4% (95% confidence interval [CI], 4.0-9.97) of scarred subjects had trichiasis develop, 5.96% (95% CI, 3.67-9.42) had corneal opacity develop, 16.51% (95% CI, 12.71-21.13) had visual impairment/blindness develop, and 2.5% (95% CI, 1.2-5.0) had corneal visual impairment/blindness develop. Mandinka ethnicity was a risk factor for trichiasis (odds ratio [OR], 4.3; 95% CI, 1.3-14.4), and trichiasis at baseline was a risk factor for corneal opacity (OR, 8.4; 95% CI, 1.8-39.2). History of lid surgery for trichiasis was associated with corneal opacity at follow-up (OR, 4.4; 95%CI, 1.4-14.0). Older age was a significant risk factor for development of trichiasis, corneal opacity, and visual loss (OR, 1.07; 95% CI, 1.01-1.12). Bilateral cataract was present in 40% of traced subjects and was associated with the incidence of visual impairment/blindness (OR, 9.4; 95%CI, 4.5-19.6) CONCLUSIONS: This is the first study to demonstrate the link between trichiasis and future corneal opacity, and it provides the rationale for performing lid rotation surgery on patients with trichiasis who do not yet have corneal opacity. The association between corneal opacity at follow-up and previous surgery among trichiasis patients suggests late presentation as a problem. The planning of surgical services will be aided by the incidence figures generated by this study.

Efficacy of oral azithromycin versus topical tetracycline in mass treatment of endemic trachoma.

OBJECTIVE: To compare the impact of mass treatment with oral azithromycin and topical tetracycline on the prevalence of active trachoma. METHODS: A total of 1803 inhabitants from 106 households of eight Gambian villages were randomized, in pairs, to receive either three doses of azithromycin at weekly intervals, or daily topical tetracycline over 6 weeks. Ocular examinations were conducted before treatment, and 2, 6 and 12 months after treatment. FINDINGS: Prior to treatment, 16% of the study participants had active trachoma. Two months after treatment, the prevalence of trachoma was 4.6% and 5.1% in the azithromycin and the tetracycline groups, respectively (adjusted odds ratio (OR) = 1.09; 95% confidence interval (CI) = 0.53, 2.02). Subsequently, the prevalence rose to 16% in the tetracycline group, while remaining at 7.7% in the azithromycin group (adjusted OR at 12 months = 0.52; 95% CI = 0.34, 0.80). At 12 months post-treatment, there were fewer new prevalent cases in the azithromycin group, and trachoma resolution was significantly better for this group (adjusted OR = 2.02; 95% CI = 1.42, 3.50). CONCLUSION: Oral azithromycin therefore appears to offer a means for controlling blinding trachoma. It is easy to administer and higher coverages may be possible than have been achieved hitherto.

Understanding the community perspectives of trachoma: The Gambia as a case study.

Trachoma has justifiably attracted an incredibly large amount of research interest and literature over the last several decades. Perhaps, the area which is least explored is the social aspect of the disease. Most of the major constraints to trachoma control on the global scale appear to be concerned with this aspect of the disease. Recently, a study was conducted in The Gambia with the aim of highlighting the socio-cultural determinants of trachoma. We applied qualitative methods of Focus Group Discussion and Semi-structured interview to explore the local people's concepts of the disease among two traditional ethnic groups, the Jolas and the Manjagos, in five rural communities. Our results show that there appears to be a poor understanding of the chronic nature of the active inflammatory phase of trachoma among the local people. But more importantly, there is a lack of mental connection between this childhood infection and blindness resulting from trichiasis in adults. This probably explains why it is difficult for the people in these communities to see the need for prolonged use of antibiotic eye ointment as required in the treatment of active inflammatory trachoma. Moreover, the local concepts about the cause(s) of the disease tend to compel the people to seek the traditional herbal remedies first, though there is adequate knowledge and experience among them that modern methods of treatment may produce cure, as in the case of corrective lid surgery for trichiasis. This ambivalent attitude of the people to health services appear to be a universal phenomenon in many local communities in Africa, and perhaps hinges on the local people's perspective of the disease, which varies from place to place. We conclude that for any intervention strategy to achieve the set goals of eliminating trachoma in spite of these constraints, community support and participation is essential, and in order to achieve this, the health care provider needs to have a better understanding of the community perspectives of the disease.

Operational comparison of single-dose azithromycin and topical tetracycline for trachoma.

PURPOSE: World Health Organization guidelines for antibiotic treatment of trachoma currently include a 6-week course of tetracycline eye ointment twice daily or a single dose of oral azithromycin. Previous trials have shown similar efficacy of these two alternatives when administration of the ointment was carefully supervised. It is believed, however, that azithromycin may be a more effective treatment in practice, and the purpose of this study was to test that hypothesis. METHODS: A masked randomized controlled trial was conducted to compare azithromycin and tetracycline under practical operational conditions-i.e., without supervision of the administration of the ointment. Three hundred fourteen children aged 6 months to 10 years with clinically active trachoma were recruited and individually randomized to receive one of the two treatments. Follow-up visits were conducted at 10 weeks and 6 months. The outcome was resolution of disease (clinical "cure"). RESULTS: Children allocated to azithromycin were significantly more likely to have resolved disease than those allocated to tetracycline, both at 10 weeks (68% versus 51%; cure rate ratio, 1.31; 95% confidence interval [CI], 1.08-1.59; P = 0.007) and at 6 months (88% versus 73%; cure rate ratio, 1.19; 95% CI, 1.06-1.34; P = 0.004). Azithromycin was particularly effective for intense inflammation (P = 0.023, Fisher's exact test). CONCLUSIONS: Single-dose oral azithromycin was a more effective treatment for active trachoma than tetracycline ointment as applied by caregivers. The high cure rate achieved with tetracycline in this study in the absence of supervision and the significantly higher costs of azithromycin, suggest that in the absence of donation programs, switching routine treatment from tetracycline to azithromycin would not be a good use of resources.

Evaluation of a national eye care programme: re-survey after 10 years.

AIM: To re-survey the Gambia after an interval of 10 years to assess the impact of a national eye care programme (NECP) on the prevalence of blindness and low vision. METHOD: Comparison of two multistage cluster random sample surveys taking into account the marked increase in population in the Gambia, west Africa. Samples of the whole population in 1986 and 1996 were taken. The definition of blindness is presenting vision less than 3/60 in the better eye, or visual fields constricted to less than 10 degrees from fixation. Low vision is less than 6/18 but 3/60 or better. Causes of blindness were determined clinically by three ophthalmologists. RESULTS: The crude prevalence of blindness fell from 0.70% to 0.42%, a relative reduction of 40%. During the same 10 year period, the population increased by 51% from 775 000 to 1 169 000. When the results were standardised for age, a west to east gradient was found for changes in risk of blindness over the 10 year period. This matched the phased west to east introduction of the NECP interventions. There was a modest but significant increase in the risk of low vision across the whole country. CONCLUSIONS: The overall reduction in risk of blindness, in those areas where the NECP has been active, appears to justify the programme and the support of donor organisations. The low vision cases due to cataract must now be addressed.

Should trichiasis surgery be offered in the village? A community randomised trial of village vs. health centre-based surgery.

INTRODUCTION: Surgery for trachomatous trichiasis prevents blindness and is advocated by the WHO as part of the SAFE strategy for the global elimination of trachoma. We conducted a randomised community trial to investigate the effect of providing surgery in villages on surgical uptake in The Gambia. METHODS: 56 villages from two divisions were assigned to eight pairs of clusters matched by geographical division and proximity. One cluster from each pair was randomly assigned to receive village-based surgery and the other cluster health centre-based surgery. Outcome measures were uptake rates and surgical results after 1 week and 3 months. The paired t-test was used to analyse the results. RESULTS: Overall uptake was 66% in the village-based clusters and 44% in the health centre-based clusters. Subjects in the village-based surgery arm had significantly shorter journey times (P = 0.01) and lower costs (P = 0.002). The mean difference in absolute acceptance rates of surgery was 20% better in village-based clusters (95% CI -9 to + 49%, P = 0.15), which would equate to an improvement of 45% (95% CI -20% to 120%) on the average acceptance rates of 44% in the health centre-based group. CONCLUSION: These results strongly suggest better surgical uptake when surgery is provided in patients' villages due to lower cost to the patient, time saved and less fear of the operation.

Long-term follow-up of lid surgery for trichiasis in the Gambia: surgical success and patient perceptions.

BACKGROUND: Surgery is an important component of the SAFE strategy which has been shown to improve visual acuity. There are limited data on long-term surgical success and patient perceptions and satisfaction. A sample of patients from the Gambia who had undergone previous lid surgery for trichiasis were therefore examined for recurrence of trichiasis and interviewed for patient satisfaction. METHODS: Health centre surgical records and community screening were used to identify patients who had undergone previous lid surgery. Consenting patients were examined and a questionnaire administered. Kaplan-Meier survival plots were constructed for recurrence of trichiasis. RESULTS: Sixty-five subjects were recruited. Median age at surgery was 50 years. Median time since surgery was 7 years. Fifty-two of 115 (45%) operated eyes were free of trichiasis at follow-up and 23 of 65 (35%) patients had not suffered recurrent trichiasis in an operated eye. Median time from surgery to recurrence of trichiasis was estimated as 10.0 years (95% CI 3.7-16.3). Recurrent trichiasis was not significantly associated with visual impairment or blindness at follow-up. The following patient perceptions were reported: satisfaction with surgery (88%), less discomfort than before surgery (93%), improved vision (83%), work easier (38%), worth the expenditure (94%), would recommend it to others (93%), had recommended it to others (38%), experienced intra-operative pain (26%) and experienced post-operative pain (26%). CONCLUSION: Factors affecting surgical success, including surgical technique and re-exposure to infection, are discussed. This study provides important preliminary data for programme planners but larger prospective studies are required.

Retinal manifestations of HIV-1 and HIV-2 infections among hospital patients in The Gambia, west Africa.

BACKGROUND: In developed countries, 50-75% of AIDS patients develop retinal complications and about 20-40% acquire cytomegalavirus (CMV) retinitis. We conducted a cross-sectional survey to determine prevalence of these in The Gambia where both HIV-1 and HIV-2 infection are present and the prevalence of HIV-1 is rising. METHOD: All patients attending hospital whose percentage CD4+ cells (CD4%) was below 14, the level associated typically with an AIDS diagnosis, and one half of those whose CD4% was 14 or above were asked to join the study. Fifty-six HIV-1, 52 HIV-2 and 12 dually infected patients were recruited. Photographs of the fundi were taken and interpreted independently. The findings were related to the patients' percentage CD4+ cells. RESULTS: The CD4% was < 14 in 40 patients and < 7 in 17 patients. Thirty-six patients were male. No cases of CMV retinitis were found. Four patients whose CD4% were 4, 5, 11 and 23 had cotton wool spots ranging in number from 1 to 14 for any one patient. The prevalence of cotton wool spots was 8% (95% CI, 0-16%) among patients with CD4% below 14 and 12% (95% CI, 0-27) among patients with CD4% below 7. One of the 4 patients had associated microaneurysm and blot haemorrhages typical of more advanced HIV microvasculopathy. CONCLUSION: CMV retinitis is less common in The Gambia than in developed countries. Non-infectious retinopathy may also be less common.

Is there a role for glycosuria testing in sub-Saharan Africa?

BACKGROUND: With increasing urbanization and westernization, rates of diabetes in sub-Saharan Africa (sSA) are likely to rise. Early detection and intervention plays an important role in delaying development of complications. In sSA in particular there is need for an affordable, reliable, safe, feasible test to avert human suffering and exhausting already stressed health facilities. METHODS: Data from two large community-based studies were used to assess the value of glycosuria testing in the detection of diabetes in adults in a sub-Saharan country. A first study (A) tested participants for glycosuria by dipstick; if positive, fasting capillary glucose was measured. A later study (B) measured glucose concentration in venous blood 2 h after a 75-g glucose load; if glycaemia was > or = 10 mmol/l, urine was tested for glycosuria. RESULTS: The positive predictive value of glycosuria for a diagnosis of diabetes (fasting glucose > or = 6.7 mmol/l) was 48%. Sensitivity was 64% (57% if a 2-h-value > or = 10 mmol/l was used as gold standard). Sensitivity was higher among overweight and/or hypertensive subjects, among elderly people in the urban area, and among subjects with higher blood glucose levels. Extrapolated specificity was 99.7%, and the likelihood ratio 190. CONCLUSIONS: Glycosuria testing can identify a considerable number of undiagnosed diabetic patients when specially targeted at high-risk groups (obese, hypertensive, or elderly people). Dipstick glycosuria testing is an appropriate, safe, feasible test for sSA, where the prevalence of diabetes is expected to increase considerably in the near future.

Azithromycin in control of trachoma.

BACKGROUND: Trachoma is the leading cause of preventable blindness. Programmes to prevent blindness due to trachoma are based on community-wide treatment with topical tetracycline. We assessed the potential of community-wide azithromycin treatment for trachoma control. METHODS: Pairs of villages in trachoma endemic areas of Egypt, The Gambia, and Tanzania were matched on trachoma rates in 1-10-year-old children. Villages were randomly assigned community-wide oral azithromycin treatment (three doses with intervals of 1 week) or treatment with 1% topical tetracycline (once daily for 6 weeks). Clinical examinations were done at baseline, 2-4.5 months, and 12-14 months after treatment. Chlamydia trachomatitis was identified by ligase chain reaction (LCR). Analyses were by intention to treat. Univariate comparisons and multivariate analyses were used to compare outcomes. FINDINGS: LCR positivity was correlated with clinical severity, but about 30% of Egyptian and Gambian villagers with no active disease were LCR positive. Village-wide LCR positivity ranged from 16.5% (Tanzania) to 43.6% (Egypt). Treatment compliance was over 90% except in the tetracycline treatment village in Egypt. Of the participants initially LCR positive, 866 (95%) of 924 who received at least one azithromycin dose and 482 (82%) of 587 who received 28 days or more topical tetracycline, were negative at follow-up. At 1 year, village-wide LCR positivity rates were substantially lower than at baseline with both treatments; the decreases were greater with azithromycin than with tetracycline (93% vs 77% in Egypt, 78 vs 66% in The Gambia, 64 vs 55% in Tanzania). Similarly, greater reduction in clinical activity occurred after azithromycin. In multivariate analyses, factors associated with being LCR positive at 1 year were: not receiving azithromycin; age under 10 years; and LCR positivity at baseline. INTERPRETATION: Community-wide treatment with oral azithromycin markedly reduces C. trachomatis infection and clinical trachoma in endemic areas and may be an important approach to control of trachoma.

Effect of fly control on trachoma and diarrhoea.

BACKGROUND: Domestic flies are accepted vectors of diarrhoea, but their role in trachoma transmission has never been quantified and no study has shown that fly control decreases the prevalence of trachoma. We assessed the effect of fly control on public health in a pilot study in Gambian villages. METHODS: We studied two pairs of villages--one pair in the 1997 wet season, and one pair in the 1998 dry season. For each pair, deltamethrin was sprayed for 3 months to control flies in one village whilst the other was used as a control. Fly populations were monitored with traps. We surveyed trachoma at baseline and at 3 months, and collected daily data on diarrhoea in children aged between 3 months and 5 years. FINDINGS: Fly control decreased numbers of muscid flies by around 75% in the intervention villages compared with controls. Trachoma prevalence was similar at baseline (wet season, prevalence in intervention village 8.8% vs control 12.2%; dry season, 18.0% vs 16.0%), but after 3 months of fly control there were 75% fewer new cases of trachoma in the intervention villages (wet season 3.7% vs 13.7%; dry season 10.0% vs 18.9%; rate ratio and relative risk of pooled data 0.25 [adjusted 95% CI 0.09-0.64], p=0.003). There was 22% less childhood diarrhoea in the wet season (14% vs 19%, period prevalence ratio 0.78 [0.64-0.95], p=0.01), and 26% less diarrhoea in the dry season (6% vs 8%; 0.74 [0.34-1.59], p=0.60) compared with controls. INTERPRETATION: Muscid flies are important vectors of trachoma and childhood diarrhoea in The Gambia. Deltamethrin spray is effective for fly control and may be useful for reducing trachoma and diarrhoea in some situations, but further research on sustainable fly-control methods is needed.

PIP: The causative agent of trachoma, Chlamydia trachomatis, has been found on flies fed on heavily infected laboratory culture media. Findings are presented from an assessment of the effect of domestic fly control upon the prevalence of trachoma and associated cases of childhood diarrhea in 2 pairs of Gambian villages. 1 pair of villages was studied in the 1997 wet season and the second pair in the 1998 dry season. For each pair, deltamethrin was sprayed for 3 months to control flies in 1 village, while the other village was used as a control. Fly populations were monitored with traps. The prevalence of trachoma was measured at baseline and at 3 months, and data were collected daily on diarrhea in children aged 3 months to 5 years. Fly control decreased the numbers of muscid flies by approximately 75% in the intervention villages compared with controls. While the prevalence of trachoma was similar at baseline between study and control villages, after 3 months of fly control there were 75% fewer new cases of trachoma in the intervention villages. There was 22% and 26% less childhood diarrhea in the wet and dry seasons, respectively, compared with controls. These findings demonstrate that muscid flies are important vectors of trachoma and childhood diarrhea in The Gambia, and that the use of deltamethrin spray can help to reduce the prevalence of both trachoma and associated diarrhea cases.

Trachoma in The Gambia.

BACKGROUND: As part of the second National Survey of Blindness and Low Vision in the Gambia carried out in 1996, all survey participants were examined for signs of trachoma. The findings were compared with the results of the first survey in 1986, which used the same sampling strategy. METHODS: A multistage stratified cluster random sample, with proportional probability sampling, was obtained. Stratification included settlement size (less than 400 residents, and 400 and more residents). All subjects were examined for trachoma using the simplified WHO grading system. RESULTS: Of the sample of 14,110 people, 13,047 (92.5%) were examined. Active inflammatory trachoma (grade TF or TI) was found in 3.0% of all age groups and 5.9% of children aged 0-9 years old. Trichiasis was found in 3.3% and trachomatous corneal opacities in 0.9% of adults aged 30 and over. The prevalence of blinding trachomatous corneal opacities was 0.02%, compared with 0.10% 10 years previously. CONCLUSION: Compared with a previous national survey undertaken in 1986, prevalence of active trachoma has fallen by 54%. There has been an 80% relative reduction in blinding trachomatous corneal opacities over the 10 year period.