ABSTRACT
Purpose: To determine the prevalence of trachoma and water and sanitation coverage in four local government areas (LGAs) of Jigawa State, Nigeria: Birnin Kudu, Buji, Dutse and Kiyawa.
Methodology: A population-based cross-sectional survey was conducted in each LGA using Global Trachoma Mapping Project (GTMP) protocols. From each LGA, 25 villages were selected using probability-proportional-to-population size sampling; in each village, 25 households were selected using the random walk technique. All residents aged ≥1 year in selected households were examined by GTMP-certified graders for trachomatous inflammation – follicular (TF) and trichiasis, defined according to the WHO simplified trachoma grading scheme definitions. Water, sanitation and hygiene data were also collected through questioning and direct observation.
Results: In 2458 households of four LGAs, 10,669 residents were enumerated. A total of 9779 people (92% of residents) were examined, with slightly more females examined (5012; 51%) than men. In children aged 1–9 years, the age-adjusted prevalence of TF ranged from 5.1% (95% CI 2.5–9.0%) in Birnin Kudu to 12.8% (95% CI 7.6–19.4%) in Kiyawa, while the age- and gender-adjusted trichiasis prevalence in persons aged ≥15 years ranged from 1.9% (95% CI 1.4–2.5%) in Birnin Kudu to 3.1% (95% CI 2.2–4.0) in Dutse. Access to improved water sources was above 80% in all LGAs surveyed but access to improved sanitation facilities was low, ranging from 23% in Buji to 50% in Kiyawa.
Conclusion: Trachoma is a public health problem in all four LGAs surveyed. The full SAFE strategy needs to be implemented to achieve trachoma elimination.
Introduction
Trachoma is a disease caused by repeated infection of the conjunctival epithelium by particular strains of the bacterium Chlamydia trachomatis;1,Citation2 it is the principal cause of blindness of infectious origin worldwide.Citation3 The main reservoir of the infection is in young children,Citation4 in whom the clinical sign of trachomatous inflammation – follicular (TF), a feature of prolonged C. trachomatis-induced conjunctival inflammation, is often found.Citation5 Frequent repeated infection and inflammation of the conjunctivae,Citation6,Citation7 can lead to conjunctival scarring, with resultant in-turning of the eyelashes. In-turned eyelashes that touch the eyeball (trichiasis)Citation5 may damage the cornea, resulting in irreversible visual impairment or blindness.
An estimated 171 million people are at risk of the disease in Africa.Citation8 In Nigeria, various surveys have shown trachoma to be of public health significance in many local government areas (LGAs, the equivalent of “districts” elsewhere).Citation9–Citation14 To implement the SAFE (Surgery for trichiasis, Antibiotics to clear infection, and promotion of Facial cleanliness and Environmental improvement to reduce transmission) strategy, which is recommended by the World Health Organization (WHO) for the elimination of trachoma,Citation15 district-level data on the prevalence of TF in 1–9 year-olds and trichiasis in persons aged ≥15 years are required. These data help programme managers determine which elements of the strategy to implement.Citation16
Jigawa State is located in northern Nigeria and surrounded by states where trachoma has been found to be a public health problem.Citation9,Citation14,Citation17 A 2007 state-level survey also documented trachoma to be a public health problem in Jigawa State itself; although this work did not generate the LGA-level prevalence indicators generally recommended to guide programme implementation,Citation18 it was used as the basis to initiate SAFE strategy rolloutCitation19 for a number of LGAs. In 2013, the Global Trachoma Mapping Project (GTMP)Citation20 supported the collection of LGA-level data in four LGAs of Jigawa where elimination activities had not yet commenced.
Methods
Sample size calculation
Each LGA was considered its own evaluation unit, with a separate population-based prevalence survey being conducted in each one, according to the same principles. Details of the sample size calculation have been reported elsewhere.Citation21 Briefly, each survey attempted to include enough households to ensure that 1019 children aged 1–9 years would be present and consent to participate, because this would provide sufficient power to estimate an expected TF prevalence in 1–9-year olds of 10% with an absolute precision of 3%, assuming a design effect of 2.65.
Team training
Each field team consisted of a grader and a recorder. These personnel were trained and certified according to the standard operating procedures of the GTMP.Citation21 Version 1 of the GTMP training systemCitation22 was used. Grader trainees were required to pass a slide-based test of diagnostic accuracy after which they were eligible to attempt live subject-based inter-grader assessment tests to prove themselves survey-ready, while recorder trainees were required to pass an examination testing their data capture accuracy, as described previously.Citation21
Household selection
In each LGA, 25 villages were selected using a systematic, probability-proportional-to-population-size methodology.Citation16 In selected villages, 25 households were selected. Despite the limitations of the random walk method,Citation23–Citation25 it was used to select households as the security situation at that time was volatile and survey coordinators felt it was better to use a method with which communities were familiar.
Data collection
Members of selected households aged ≥1 year were eligible to be included. With the aid of ×2.5 magnifying loupes, graders examined the eyes of all consenting participants for the signs of trichiasis, TF and trachomatous inflammation – intense (TI), according to the criteria of the WHO simplified grading system.Citation5 Collection of data on household-level sources of water and the type of sanitation facility was integrated into the survey, through interviews with household members plus direct observation. All data were entered into the LINKS-GTMP app running on Android smartphones, which automatically collected global positioning system (GPS) coordinates for each household.Citation21 Once phones were within range of a suitable network, data were uploaded to a secure cloud-based server.Citation21,Citation26
Data analysis
The Nigeria census for 2006Citation27 was used as the reference for data adjustment. The proportion of 1–9-year-olds with TF was adjusted at village level for age, in one year age bands. The proportion of adults with trichiasis was adjusted at village level for gender and age, in 5-year age bands. The means of the adjusted village-level proportions provided the LGA-level prevalences. Confidence intervals (CIs) were determined by bootstrapping adjusted village-level proportions, with replacement, over 10,000 replications.
Water sources and sanitation facilities were defined as “improved” using the criteria established by the WHO/UNICEF Joint Monitoring Program (JMP) for Water Supply and Sanitation, as reported up until 2015.Citation28
Ethical considerations
Ethical approval was obtained from the National Health Research Ethics Committee of Nigeria (NHREC/01/01/2007) and the ethics committee of the London School of Hygiene & Tropical Medicine (reference 6319). Consent was obtained verbally, and documented electronically. For individuals below 15 years of age, consent was given by a parent or guardian. Persons with active trachoma were given a course of 1% topical tetracycline eye ointment, and those with trichiasis were referred to the nearest certified trichiasis surgeon.
Results
Residents enumerated from 2458 households across the four LGAs totalled 10,669. A total of 5,538 (52%) residents were female (). A total of 9779 people (92% of residents) were examined; 473 people (4%) were absent, while 447 people (4%) refused examination (). Of examined individuals, 5012 (51%) were female.
Table 1. Number of 1–9-year olds and number of ≥15-year-olds resident, examined, absent and refused; prevalence of trachomatous inflammation – follicular (TF); and prevalence of trichiasis; by Local Government Area (LGA), Global Trachoma Mapping Project Jigawa State, Nigeria, June and July, 2013.
A total of 3,611 children aged 1–9 years were examined, of whom 1775 (49%) were female. The age-adjusted prevalence of TF in 1–9-year-olds ranged from 5.1% (95% CI 2.5–9.0%) in Birnin Kudu to 12.8% (95% CI 7.6–19.4%) in Kiyawa (, ).
Figure 1. Local Government Areas (LGAs) surveyed, and prevalence of trachomatous inflammation—follicular (TF) in 1–9-year-olds, by LGA, Jigawa State, Nigeria, June and July, 2013. GTMP: Global Trachoma Mapping Project.
A total of 5,435 individuals aged ≥15 years were examined. Of those, 2,878 (53%) were female. The age- and gender-adjusted prevalence of trichiasis in ≥15-year-olds ranged between 1.9% (95% CI 1.4–2.5%) in Birnin Kudu and 3.1% (95% CI 2.2–4.0) in Dutse ( and ). The estimated backlog of trichiasis and the number of persons needing surgery to reach the elimination threshold in each LGA is shown in .
Table 2. Household-level access to water and sanitation, by Local Government Area (LGA), Global Trachoma Mapping Project, Jigawa State, Nigeria, June and July, 2013.
Table 3. Local Government Area (LGA)-level estimates of the trichiasis backlog, Jigawa State, Nigeria. Global Trachoma Mapping Project, June and July 2013.
Figure 2. Prevalence of trichiasis in ≥15-year-olds, by LGA, Jigawa State, Nigeria, June and July, 2013. GTMP: Global Trachoma Mapping Project.
In all four LGAs surveyed, over 80% of households had access to an improved source of water for face-washing within a 30 minute round trip (the equivalent of a < 1 km round trip). Household access to improved sanitation facilities ranged from 23.1% in Buji to 50.2% in Kiyawa ().
Discussion
In all four LGAs surveyed here, trachoma was a public health problem, as perhaps might have been predicted on the basis of 2007 state-level survey data.Citation18 All LGAs surveyed require interventions for active trachoma, comprising antibiotic mass drug administration, promotion of facial cleanliness and environmental improvement.Citation16 While Birnin Kudu, Buji and Dutse will require these interventions for at least one year, Kiyawa will require them for at least three years before impact surveys would be recommended.Citation29 Considering the relatively high household-level water coverage (>80%) in all LGAs surveyed, in order to faithfully implement the SAFE strategy, emphasis should be placed on encouraging use of water for hygiene purposes, perhaps using established hygiene behaviour change techniques.Citation30 Residents of these LGAs need to be able to relate the disease trachoma to poor personal hygiene so that water is used to ensure that faces are clean. . Success in this area might be anticipated, as the hardware is already available to implement the ‘F’ component of SAFE.
Availability of improved sanitation facilities was noted to be suboptimal. Though sanitation coverage was above the 2008 national average of 18%,Citation31 there remains considerable room for improvement. Some studies associate latrine ownership with a lower risk of trachoma,Citation32–Citation34 and a recent model incorporating GTMP data from 13 countries, including Nigeria, found evidence of herd protection against TF for children living in communities in which sanitation coverage is >80%.Citation35 To succeed in implementing the ‘E’ component of the SAFE strategy here, greater attention to providing the means for appropriate disposal of human faeces is recommended.
The trichiasis prevalence was above the elimination threshold in each LGA surveyed. In these four LGAs, an estimated 11,479 people have the potentially blinding stage of trachoma; if left untreated, this could progress in each person to cause corneal damage and irreversible visual impairment or blindness. There is therefore an urgent requirement to scale-up the surgery component of the SAFE strategy. A programme that provides surgery as close as possible to the residences of persons affectedCitation36 is needed to encourage all trichiasis patients to present for surgery; we note that in many places, women have lower access to trichiasis surgery services, are more afraid of surgery, and are less likely to have been offered surgery in the past.Citation37 Thankfully, Jigawa State has already started training trichiasis surgeons to meet the predicted service requirements. In these four LGAs alone, a total of 10,643 trichiasis surgeries are likely to be needed to reach the elimination prevalence target. Training and certification of trichiasis surgeons will need to follow WHO recommendations.Citation38 This will ensure that when surgeons are equipped and deployed, they provide high quality surgery to persons afflicted.
Trachoma is a public health problem in all four LGAs of Jigawa State surveyed in this series. There is a need to implement the full SAFE strategy in each of them, in order to move towards elimination of trachoma as a public health problem.
Declaration of interest
The authors report no conflicts of interest. The authors alone are responsible for the writing and content of this article.
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References
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Appendix
The Global Trachoma Mapping Project Investigators are: Agatha Aboe (1,11), Liknaw Adamu (4), Wondu Alemayehu (4,5), Menbere Alemu (4), Neal D. E. Alexander (9), Ana Bakhtiari (2,9), Berhanu Bero (4), Sarah Bovill (8), Simon J. Brooker (1,6), Simon Bush (7,8), Brian K. Chu (2,9), Paul Courtright (1,3,4,7,11), Michael Dejene (3), Paul M. Emerson (1,6,7), Rebecca M. Flueckiger (2), Allen Foster (1,7), Solomon Gadisa (4), Katherine Gass (6,9), Teshome Gebre (4), Zelalem Habtamu (4), Danny Haddad (1,6,7,8), Erik Harvey (1,6,10), Dominic Haslam (8), Khumbo Kalua (5), Amir B. Kello (4,5), Jonathan D. King (6,10,11), Richard Le Mesurier (4,7), Susan Lewallen (4,11), Thomas M. Lietman (10), Chad MacArthur (6,11), Colin Macleod (3,9), Silvio P. Mariotti (7,11), Anna Massey (8), Els Mathieu (6,11), Siobhain McCullagh (8), Addis Mekasha (4), Tom Millar (4,8), Caleb Mpyet (3,5), Beatriz Muñoz (6,9), Jeremiah Ngondi (1,3,6,11), Stephanie Ogden (6), Alex Pavluck (2,4,10), Joseph Pearce (10), Serge Resnikoff (1), Virginia Sarah (4), Boubacar Sarr (5), Alemayehu Sisay (4), Jennifer L. Smith (11), Anthony W. Solomon (1,2,3,4,5,6,7,8,9,10,11), Jo Thomson (4); Sheila K. West (1,10,11), Rebecca Willis (2,9).
Key: (1) Advisory Committee, (2) Information Technology, Geographical Information Systems, and Data Processing, (3) Epidemiological Support, (4) Ethiopia Pilot Team, (5) Master Grader Trainers, (6) Methodologies Working Group, (7) Prioritisation Working Group, (8) Proposal Development, Finances and Logistics, (9) Statistics and Data Analysis, (10) Tools Working Group, (11) Training Working Group