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Risk Factors for Active Trachoma and Ocular Chlamydia trachomatis Infection in Treatment-Na?ve Trachoma-Hyperendemic Communities of the Bijagós Archipelago, Guinea Bissau

DOI: 10.1371/journal.pntd.0002900

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Background Trachoma, caused by ocular infection with Chlamydia trachomatis, is hyperendemic on the Bijagós Archipelago of Guinea Bissau. An understanding of the risk factors associated with active trachoma and infection on these remote and isolated islands, which are atypical of trachoma-endemic environments described elsewhere, is crucial to the implementation of trachoma elimination strategies. Methodology/Principal Findings A cross-sectional population-based trachoma prevalence survey was conducted on four islands. We conducted a questionnaire-based risk factor survey, examined participants for trachoma using the World Health Organization (WHO) simplified grading system and collected conjunctival swab samples for 1507 participants from 293 randomly selected households. DNA extracted from conjunctival swabs was tested using the Roche Amplicor CT/NG PCR assay. The prevalence of active (follicular and/or inflammatory) trachoma was 11% (167/1508) overall and 22% (136/618) in 1–9 year olds. The prevalence of C. trachomatis infection was 18% overall and 25% in 1–9 year olds. There were strong independent associations of active trachoma with ocular and nasal discharge, C. trachomatis infection, young age, male gender and type of household water source. C. trachomatis infection was independently associated with young age, ocular discharge, type of household water source and the presence of flies around a latrine. Conclusions/Significance In this remote island environment, household-level risk factors relating to fly populations, hygiene behaviours and water usage are likely to be important in the transmission of ocular C. trachomatis infection and the prevalence of active trachoma. This may be important in the implementation of environmental measures in trachoma control.


[1]  World Health Organization (2012) Prevention of blindness and visual impairment (Priority Eye Diseases): Trachoma. Available:
[2]  Solomon AW, Peeling RW, Foster A, Mabey DCW (2004) Diagnosis and Assessment of Trachoma. Clin Micro Rev 17 (4) 982–1011. doi: 10.1128/cmr.17.4.982-1011.2004
[3]  Ramesh A, Kovats S, Haslam D, Schmidt E, Gilbert CE (2013) The impact of climatic risk factors on prevalence, distribution, and severity of acute and chronic trachoma. PLoS Negl Trop Dis 7 (11) e2513. doi: 10.1371/journal.pntd.0002513
[4]  National Population Census (Bolama-Bijagós Region) (2010) Instituto Nacional de Estatística, Bissau, Guiné-Bissau.
[5]  World Bank (2013) From the Climatic Research Unit (CRU) at the University of East Anglia (UEA). Climate Change Knowledge Portal: Guinea Bissau. Available:
[6]  Burton MJ, Holland MJ, Faal N, Aryee EA, Alexander ND, et al. (2003) Which members of a community need antibiotics to control trachoma? Conjunctival Chlamydia trachomatis infection load in Gambian villages. Invest Ophthalmol Vis Sci 44: 4215–4222. doi: 10.1167/iovs.03-0107
[7]  Emerson PM, Cairncross S, Bailey RL, Mabey DC (2000) Review of the evidence base for the ‘F’ and ‘E’ components of the SAFE strategy for trachoma control. Trop Med Int Health 5: 515–527. doi: 10.1046/j.1365-3156.2000.00603.x
[8]  Emerson PM, Lindsay SW, Alexander N, Bah M, Dibba SM, et al. (2004) Role of flies and provision of latrines in trachoma control: cluster randomized controlled trial. Lancet 363: 1093–1098. doi: 10.1016/s0140-6736(04)15891-1
[9]  Taylor HR, Velasco FM, Sommer A (1985) The ecology of trachoma: an epidemiological study in southern Mexico. Bull World Health Organ 63: 559–567.
[10]  Bailey R, Osmond C, Mabey DC, Whittle HC, Ward ME (1989) Analysis of the household distribution of trachoma in a Gambia village using a Monte Carlo simulation procedure. Int J Epidemiol 18: 944–951. doi: 10.1093/ije/18.4.944
[11]  Burton MJ, Holland MJ, Makalo P, Aryee EA, Alexander ND (2005) Re-emergence of Chlamydia trachomatis infection after mass antibiotic treatment of a trachoma-endemic Gambian community: a longitudinal study. Lancet 365: 1321–8. doi: 10.1016/s0140-6736(05)61029-x
[12]  West SK, Munoz B, Turner VM, Mmbaga BB, Taylor HR (1991) The epidemiology of trachoma in central Tanzania. Int J Epidemiol 20: 1088–1092. doi: 10.1093/ije/20.4.1088
[13]  Blake IM, Burton MJ, Bailey RL, Solomon AW, West SK (2009) Estimating household and community transmission of ocular Chlamydia trachomatis. PLoS Negl Trop Dis 3: e401. doi: 10.1371/journal.pntd.0000401
[14]  Kuper H, Solomon AW, Buchan J, Zondervan M, Foster A, et al. (2003) A critical review of the SAFT strategy for the prevention of blinding trachoma. Lancet Infect Dis 3: 372–381. doi: 10.1016/s1473-3099(03)00659-5
[15]  WHO (2004) Report of the eighth meeting of the WHO Alliance for the Global Elimination of Blinding Trachoma, Geneva: Switzerland. Available:
[16]  Abdou A, Nassirou B, Kadri B, Moussa F, Mu?oz B, et al. (2007) Prevalence and risk factors for trachoma and ocular Chlamydia trachomatis infection in Niger. Br J Ophthalmol 91: 13–17. doi: 10.1136/bjo.2006.099507
[17]  West SK, Rapoza P, Mu?oz B, Katala S, Taylor HR (1991) Epidemiology of ocular chlamydial infection in a trachoma-hyperendemic area. J Infect Dis 163: 752–756. doi: 10.1093/infdis/163.4.752
[18]  Harding-Esch E, Edwards T, Mkocha H, Mu?oz B, Holland MJ, et al. (2010) Trachoma prevalence and associated risk factors in The Gambia and Tanzania: Baseline results of a cluster randomized controlled trial. PLoS Negl Trop Dis 4 (11) e861. doi: 10.1371/journal.pntd.0000861
[19]  Edwards T, Harding-Esch EM, Hailu G, Andreason A, Mabey DC, et al. (2008) Risk factors for active trachoma and Chlamydia trachomatis infection in rural Ethiopia after mass treatment with azithromycin. Trop Med Int Health 13: 556–565. doi: 10.1111/j.1365-3156.2008.02034.x
[20]  Ngondi J, Reacher M, Matthews F, Brayne C, Emerson P (2009) Trachoma survey methods: A literature review. Bull World Health Organ 87: 143–51. doi: 10.2471/blt.07.046326
[21]  Bennett S, Woods T, Liyanage WM, Smith DL (1991) A simplified general method for cluster-sample surveys of health in developing countries. World Health Stat Q 44: 98–106.
[22]  Wright HR, Vu H, Taylor HR (2005) How to assess the prevalence of trachoma. Br J Ophthalmol 89: 526–7. doi: 10.1136/bjo.2005.066183
[23]  Thylefors B, Dawson CR, Jones BR, West SK, Taylor HR (1987) A simple system for the assessment of trachoma and its complications. Bull World Health Organ 65 (4) 477–83.
[24]  Keenan JD, Lakew T, Alemayehu W, Melese M, Porco TC (2010) Clinical activity and polymerase chain reaction evidence of chlamydial infection after repeated mass antibiotic treatments for trachoma. Am J Trop Med Hyg 82 (3) 482–7. doi: 10.4269/ajtmh.2010.09-0315
[25]  Stare D, Harding-Esch E, Munoz B, Bailey R, Mabey D (2011) Design and baseline data of a randomised trial to evaluate coverage and frequency of mass treatment with azithromycin: The Partnership for the Rapid Elimination of Trachoma (PRET) in Tanzania and The Gambia. Ophthalmic Epidemiol 18 (1) 20–9. doi: 10.3109/09286586.2010.545500
[26]  Michel CE, Roper KE, Divena MA, Lee HH, Taylor HR (2011) Correlation of clinical trachoma and infection in Aboriginal communities. PLoS Negl Trop Dis 5 (3) e986. doi: 10.1371/journal.pntd.0000986
[27]  Leslie DE, Azzalo F, Ryan N, Fyfe J (2003) An assessment of the Roche Amplicor Chlamydia trachomatis/Neisseria gonorrhoeae multiplex PCR assay in routine diagnostic use on a variety of specimen types. Commun Dis Intell Q Rep 27 (3) 373–9.
[28]  Holland MJ, Jeffries D, Pattison M, Korr G, Gall A (2010) Pathway focused arrays reveal increased matrix metalloproteinase-7 (Matrilysin) transcription in trachomatous trichiasis. Invest Ophthalmol Vis Sci 51 (8) 3893–3902. doi: 10.1167/iovs.09-5054
[29]  Hagi M, Schemann JF, Mauny F, Momo G, Sacko D (2010) Active trachoma among children in Mali: Clustering and environmental risk factors. PLoS Negl Trop Dis 4 (1) e583. doi: 10.1371/journal.pntd.0000583
[30]  Schemann JF, Sacko D, Malvy D, Momo G, Traore L, et al. (2002) Risk factors for trachoma in Mali. Int J Epidemiol 31: 194–201. doi: 10.1371/journal.pntd.0000583
[31]  Alemayehu W, Melese M, Fredlander E, Worku A, Courtright P, et al. (2005) Active trachoma in children in central Ethiopia: association with altitude. Trans R Soc Trop Med Hyg 99: 840–3. doi: 10.1016/j.trstmh.2005.06.013
[32]  Cumberland P, Hailu G, Todd J (2005) Active trachoma in children aged three to nine years in communities in rural Ethiopia: prevalence, indicators and risk factors. Trans R Soc Trop Med Hyg 99: 120–7. doi: 10.1016/j.trstmh.2004.03.011
[33]  Polack S, Kuper H, Solomon AW, Massae PA, Abuelo C, et al. (2006) The relationship between the prevalence of active trachoma, water availability and its use in a Tanzanian village. Trans R Soc Trop Med Hyg 100: 1075–1083. doi: 10.1016/j.trstmh.2005.12.002
[34]  Baggaley RF, Solomon AW, Kuper H, Polack S, Massae PA, et al. (2006) Distance to water source and altitude in relation to active trachoma in Rombo district, Tanzania. Trop Med Int Health 11: 220–7. doi: 10.1111/j.1365-3156.2005.01553.x
[35]  Mesfin MM, de la Camera J, Tereke IG, Ananual G, Araya T, et al. (2006) A community-based trachoma survey: Prevalence and risk factors in the Tigray region of northern Ethiopia. Ophthalmic Epidemiol 13: 173–81. doi: 10.1080/09286580600611427
[36]  Harding-Esch EM, Edwards T, Sillah A, Sarr-Sissoho I, Aryee EA, et al. (2008) Risk factors for active trachoma in The Gambia. Trans R Soc Trop Med Hyg 102: 1255–1262. doi: 10.1016/j.trstmh.2008.04.022
[37]  Golovaty I, Jones L, Gelaye B, Tilahun M, Belete H, et al. (2009) Access to water source, latrine facilities and other risk factors of active trachoma in Ankober,. Ethiopia 4 (8) e6702. doi: 10.1371/journal.pone.0006702
[38]  Bejiga A, Alemayehu W (2001) Prevalence of trachoma and its determinants in Dalocha District, Central Ethiopia. Ophthalmic Epidemiol 8: 119–125. doi: 10.1076/opep.
[39]  Bailey R, Downes B, Downes R, Mabey D (1991) Trachoma and water use: A case-control study in a Gambian village. Trans R Soc Trop Med Hyg 85: 824–8. doi: 10.1016/0035-9203(91)90470-j
[40]  Bailey R, Duong T, Carpenter R, Whittle H, Mabey D (1999) The duration of human ocular Chlamydia trachomatis is age dependent. Epidemiol Infect 123 (3) 479–86. doi: 10.1017/s0950268899003076
[41]  Gambhir M, Basanex MG, Burton MJ, Solomon AW, Bailey RL, et al. (2009) The development of an age-structured model for trachoma transmission dynamics, pathogenesis and control. PLoS Negl Trop Dis 3 (6) e462. doi: 10.1371/journal.pntd.0000462
[42]  Burton MJ, Hu VH, Massae P, Burr SE, Chevallier C, et al. (2011) What is causing active trachoma? The role of non-Chlamydial pathogens in a low prevalence setting. Invest Ophthalmol Vis Sci 52 (8) 6012–7. doi: 10.1167/iovs.11-7326
[43]  Burr SE, Hart JD, Edwards T, Baldeh I, Bojang E, et al. (2013) Association between ocular bacterial carriage and follicular trachoma following mass azithromycin distribution in The Gambia. Plos Negl Trop Dis 7 (7) e2347. doi: 10.1371/journal.pntd.0002347
[44]  O'loughlin R, Fentie G, Flannery B, Emerson PM (2006) Follow-up of a low-cost latrine promotion programme in one district of Amhara, Ethiopia: characteristics of early adopters and non-adopters. Trop Med Int Health 11 (9) 1406–15. doi: 10.1111/j.1365-3156.2006.01689.x
[45]  Brechner RJ, West S, Lynch M (1992) Trachoma and flies. Individual vs environmental risk factors. Arch Ophthalmol 110: 687–9. doi: 10.1001/archopht.1992.01080170109035
[46]  Emerson PM, Bailey RL, Walraven GE, Lindsay SW (2001) Human and other faeces as breeding media of the trachoma vector Musca sorbens. Med Vet Entomol 15 (3) 314–20. doi: 10.1046/j.0269-283x.2001.00318.x
[47]  Emerson PM, Simms VM, Makalo P, Bailey RL (2005) Household pit latrines as a potential source of the fly Musca sorbens – a one year longitudinal study from The Gambia. Trop Med Int Health 10 (7) 706–9. doi: 10.1111/j.1365-3156.2005.01432.x
[48]  Miller K, Pakpour N, Yi E, Melese M, Alemayehu W, et al. (2004) Pesky trachoma suspect finally caught. Br J Ophthalmol 88 (6) 750–1. doi: 10.1136/bjo.2003.038661
[49]  Taye A, Alemayehu W, Melese M, Gayid A, Mekonnen Y, et al. (2007) Seasonal and altitudinal variations in fly density and their association with the occurrence of trachoma in the Gurage zone of central Ethiopia. Ann Trop Med Parasitol 101 (5) 441–8. doi: 10.1179/136485907x176544
[50]  Da Cruz L, Dadour IR, McAllister IL, Jackson A, Isaacs T (2002) Seasonal variation in trachoma and bush flies in north-western Australian Aboriginal communities. Clin Experiment Ophthalmol 30 (2) 80–3. doi: 10.1046/j.1442-6404.2002.00491.x
[51]  Steyerberg EW, Eijkemans MJ, Habberna JD (1999) Stepwise selection in small data sets: a simulation study of bias in logistic regression analysis. J Clin Epidemiol 2 (10) 935–42. doi: 10.1016/s0895-4356(99)00103-1


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