OPHTHALMIC EPIDEMIOLOGY 2018, VOL. 25, NO. S1, 79–85 https://doi.org/10.1080/09286586.2018.1467466 Prevalence of Trachoma and Access to Water and Sanitation in Benue State, Nigeria: Results of 23 Population-Based Prevalence Surveys Caleb Mpyeta,b,c, Selassie Tagohd, Sophie Boissone, Rebecca Willisf, Nasiru Muhammadg, Ana Bakhtiarif, Mohammed D. Adamug, Alexandre L. Pavluckf, Murtala M. Umarh, Joel Aladai, Sunday Isiyakub, William Adamanib, Betty Jandej, Nicholas Olobiok and Anthony W. Solomonl,m,n, for the Global Trachoma Mapping Project* aDepartment of Ophthalmology, University of Jos, Jos, Nigeria; bSightsavers, Kaduna, Nigeria; cKilimanjaro Centre for Community Ophthalmology International, Division of Ophthalmology, University of Cape Town, Cape Town, South Africa; dSchool of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa; eDepartment of Public He\alth, The Environment and Social Determinants of Health, World Health Organization, Geneva, Switzerland; fTask Force for Global Health, Decatur, GA, USA; gOphthalmology Unit, Surgery Department, Usmanu Danfodiyo University, Sokoto, Nigeria; hNational Eye Centre, Kaduna, Nigeria; iDepartment of Ophthalmology, Federal Medical Centre, Makurdi, Nigeria; jMinistry of Health, Benue State, Makurdi, Nigeria; kFederal Ministry of Health, Abuja, Nigeria; lClinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom; mLondon Centre for Neglected Tropical Disease Research, London, United Kingdom; nDepartment of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland ABSTRACT ARTICLE HISTORY Purpose: We sought to determine the prevalence of trachoma in each local government area Received 13 January 2018 (LGA) of Benue State, Nigeria. Revised 17 March 2018 Methods: Two-stage cluster sampling was used to conduct a series of 23 population-based Accepted 13 April 2018 prevalence surveys. LGAs were the evaluation units surveyed. In each LGA, 25 households were KEYWORDS selected in each of 25 clusters, and individuals aged 1 year and above resident in those house- Benue State; epidemiology; holds were invited to be examined for trachoma. Data on access to water and sanitation were also Global Trachoma Mapping collected at household level. Project; Nigeria; trachoma; Results: A total of 91,888 people were examined from among 93,636 registered residents across trichiasis the 23 LGAs. The LGA-level prevalence of trachomatous inflammation—follicular (TF) in 1–9 year olds ranged from 0.3% to 5.3%. Two LGAs had TF prevalences of 5.0–9.9%. The LGA-level prevalence of trichiasis in ≥15-year-olds ranged from 0.0% to 0.35%. Access to improved drinking water sources ranged from 0% in Gwer West to 99% in Tarka, while access to improved sanitation ranged from 1% in Gwer West to 92% in Oturkpo. Conclusion: There is a need for public health-level interventions against trachoma in three LGAs of Benue State. Introduction comprehensive strategy to achieve elimination goes by the acronym “SAFE,” which represents surgery, anti- Trachoma is the world’s most common infectious cause biotics, facial cleanliness, and environmental of blindness.1 The disease is caused by repeated bouts2 improvement.8 The need for SAFE strategy implemen- of infection with the obligate intracellular bacterium tation is determined on the basis of prevalence esti- Chlamydia trachomatis, which passes from person to mates of trichiasis in ≥15-year-olds and trachomatous person through contaminated hands, through clothes inflammation—follicular (TF) in 1-9-year-olds.9 WHO and bedding, and via the eye-seeking fly, Musca recommends use of the SAFE strategy until elimination sorbens.3 Trachoma disappeared from most developed threshold prevalences (trichiasis <0.2% in ≥15-year- countries decades ago, but it continues to be a public olds and TF <5% in 1-9-year-olds) are reached in health problem in much of Africa,4,5 including each formerly endemic district.9,10 Nigeria.6 From 2012 to 2016, members of the WHO Alliance In 1996, the World Health Organization (WHO) for GET2020 made considerable progress in baseline established the WHO Alliance for the Global mapping of suspected trachoma-endemic districts Elimination of Trachoma by 2020 (GET2020).7 The worldwide within the Global Trachoma Mapping CONTACT Caleb Mpyet [email protected] Department of Ophthalmology, University of Jos, PMB 2076, Jos, Nigeria *See Appendix. © 2018 World Health Organization. Published with license by Taylor & Francis. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way. In any use of this article, there should be no suggestion that WHO endorses any specific organization, products or services. The use of the WHO logo is not permitted. This notice should be preserved along with the article’s original URL. 80 C.MPYETETAL. Project (GTMP).11 Its goal was to provide a complete letting it fall to the ground. All residents aged ≥1 year picture of the global burden of trachoma, enabling all living in the 25 households found on the heading stakeholders to see where work was needed to achieve indicated by the pen’s tip were invited to participate. elimination as a public health problem.12 Though many This sampling strategy was designed to promote other states of Nigeria had previously been mapped for recruitment of a sample of at least 1019 children aged – trachoma,13 25 no population-based surveys had been 1–9 years, as outlined previously.26 undertaken in Benue State, despite the fact that SAFE At each household, we collected GPS data on house- interventions had been required in neighbouring hold location, the type of and distance to sources of Nasarawa State, including in a number of bordering drinking and washing water in the dry season, the local government areas (LGAs).13 setting (e.g., type of shared or private latrine, outside The work described here was therefore conducted to near the home, in the bush or field) in which household (a) determine the LGA-level prevalence of TF and adults usually defecated, the presence or absence of a trichiasis in Benue, (b) determine LGA-level prevalence handwashing facility within 15 m of the latrine (if a of access to improved water and sanitation, and (c) latrine was used), and the presence or absence of water estimate the likely number of doses of antibiotics and and soap at the handwashing facility (if a handwashing the number of people to be managed for trichiasis that facility was present). This information was obtained will be needed in Benue State in order to meet the through questions asked of a household key informant targets of GET2020. and by direct inspection.28 Questions conformed clo- sely to those used up to the year 2015 by the WHO/ UNICEF Joint Monitoring Programme for Water Methods Supply and Sanitation.32,33 From each participant, we Study design and setting collected data on age, gender, and presence or absence of trichiasis, TF, and trachomatous inflammation— Surveys were undertaken between April and September intense (TI).34 2014, following standard GTMP procedures, as described previously.26 Benue State, located in the north–central zone of Nigeria, has an ethnically diverse Operational definitions population, which was estimated to total 4.3 million 27 Graders adhered to the definitions of signs in the WHO people at the last (2006) census. Benue contains 23 34 “ ” 2 simplified trachoma grading system. An improved LGAs within a land area of 34,059 km. water source was defined as one that, by nature of its construction, adequately protects the water from out- Field team preparation side contamination, in particular from faecal matter. An improved sanitation facility was defined as one Teams were trained using version 2 of the GTMP that hygienically separates human excreta from 28 training system. To be certified to participate in the human contact.32 surveys, graders were required to pass a 50-subject inter-grader agreement test in the field, with the assess- ments of a GTMP-certified grader trainer used as the Data management reference. Data recorders were also required to pass a Data were cleaned by an independent data manager 26 test before deployment. (RW), approved by the health ministry, then analysed; outputs were again approved by health ministry.26 Cluster-level proportions of children with TF were Sampling and field procedures adjusted for age in 1-year bands, and proportions of LGAs were the units of evaluation. Two-stage cluster adults with trichiasis were adjusted for gender and age sampling was undertaken. We used villages as first- in 5-year bands; local 2006 census data27 were used for stage clusters, choosing 25 of them from each of the this adjustment process. LGA-level prevalences were 23 LGAs, with probability of selection proportional to calculated as the means of adjusted cluster-level pro- village size.9 From each village, 25 households were portions. Confidence intervals (CIs) were determined selected using the random walk technique, though we by bootstrapping: sets of 25 adjusted cluster-level pro- – are aware of its limitations, detailed elsewhere.18,29 31 portions were selected, with replacement, over 10,000 With a resident’s help, the centre of the village was replications, then the 2.5th and 97.5th percentiles of the located and from that starting position a direction for ordered means of those sets formed the lower and household sampling was selected by spinning a pen and upper bounds of the CI. OPHTHALMIC EPIDEMIOLOGY 81 Ethical considerations Prevalence of trachoma Surveys were approved by the Ethics Committee of Some 43,640 1-9-year-olds were examined. The LGA- the London School of Hygiene & Tropical Medicine level prevalence of TF among 1-9-year-olds ranged (6319) and the National Health Research Ethics from 0.3% to 5.3% (Table 1).