Study design, period and setting
A community based cross-sectional study design was used from March 11/2017 to April 26/2107 in Wadla district. Wadla district is one of the administrative centers in the North Wollo zone, Amhara region. The capital city of the district is Kone. The town far away 725 km from the capital city of Ethiopia, Addis Ababa, and 75 km from Lalibela. The population of Wadla district was 128,170 with 64,574 males and 63, 596 females. There were 28,414 households in this district and resulting in having an average of 4.51 persons per house ratio [35]. The district had 1 general hospital, 7 health centers, and 20 health posts.
Population
The source population was children aged 1-5 years and their mothers in 150 rural villages of Wadla district. Whereas the study populations were children aged 1-5 years old and their mothers in 30 selected clusters or villages of Wadla district. The study units were rural households that had preschool children.
Sample size determination
The sample size estimated using a single population proportion formula. The assumptions used were a proportion of previous study 35.7% [21] from a study done in Nigeria, 95% CI, 5% margin of error, 1.5 design effect, and 10% non- response rate. It was calculated as
n = (1.96)2 (0.357X 0.643),
(0.05)2
n = 3.8416x.229551 = 352.7 ≈ 353
(0.0025)
After multiplying by the design effect of 1.5, it gave (353 X 1.5) +353 = 529.5+52.95=882.45=583 children
Sampling technique and procedure
A multistage cluster sampling technique was applied to select study subjects. Wadla district had 20 Kebeles with a total of 247 villages. Twelve of the kebeles were rural, whereas 8 of the kebeles were urban. Of the total 247 villages, 150 were rural villages. There were 967 households in the selected 30 villages, but only 499 households were had preschool children. Thus, only those 499 households were visited and all the children between 1 and 5 years of age in the house were included for the study. A cluster sampling method was used to select study units. While selecting study participants two-stage sampling techniques were used. The first stage was to select 30 of 150 rural clusters or villages as study population. The second phase was to screen all the sample, 583 children within those 30 villages or cluster. Fortunately, the number of children included in the screening were 596, whose age was between 1 and 5 years from 499 households as per the assumption of cluster sampling. The guide used for diagnosis and reporting of eye examination results was the simplified trachoma grading scheme, which was developed by WHO for fieldwork [14] (Figure 1).
The heads of the households were interviewed for sociodemographic and economic information, housing and environmental conditions. Children were examined for the signs of trachoma from the 12 selected rural kebeles, and then 30 villages accordingly.
Operational/term definitions
Clean face: A child free of either of or both of eye discharge, fly on the face of the child and nasal discharge during data collection time only
Preschool: Children greater than and equal to 1 year and less than and equal to five years
Village: An assortment of homes that contain at least 30 households together and organized as one peasant association
Active trachoma: Preschool children who develop at least one of the two active stages of trachoma (TF or TI) [2, 6, 7].
Trachomatous inflammation follicular (TF): the presence of 5 or more follicles having at least 0.5mm or greater diameter in the central upper tarsal conjunctiva [2, 6, 7].
Trachomatous Inflammation intense (TI): the presence of pronounced inflammatory thickening of the upper tarsal conjunctiva that obscures more than half of the normal deep tarsal vessels [2, 6, 7].
Trachomatous scarring (TS): the presence of easily visible scarring in the upper tarsal conjunctiva [2, 6, 7].
Trachomatous trichiasis (TT): the presence of at least one eyelash rubs on the eyeball, or evidence of eyelash removal within two weeks before data collection periods [2, 6, 7].
Corneal Opacity (CO): the presence of easily visible corneal opacity over the pupil (2, 6, and 7).
Exclusion and Inclusion Criteria
All rural preschool children who lives in the district for at least 6 months and available during the data collection period were included. Seriously ill children or mothers who was not cooperative because of their illness for the data that the researchers required were excluded.
Data collection tools and procedures
Face to face interviews, observation using a checklist, and clinical eye examination were used to collect the data. The interview part on sociodemographic status, environmental, and housing conditions were collected by experienced diploma health informatics professionals using structured interview questioners, which were prepared through reviewing pieces of literature [33, 36]. All the socio-demographic status, housing, and environmental condition, observation checklist, and eye examination tools were pretested, and validated before data collection in Kosomender, Meket district. This is one of the boundaries to the south of Wadla district. A household wealth index was computed using the composite indicator for rural residents using assets: livestock ownership, size of agricultural land and quantity of crop production.
Eye examination was performed by two integrated eye care workers (IECWs), ophthalmic nurses, who were trained for one month for the purpose of trachoma screening by Carter center-Ethiopia. The training was delivered using both pictures and live patients. Those signs of trachoma screeners were involved in two national trachoma surveys as trachoma graders. In addition, they took refreshment training for 5 days together with demographic, housing, and environmental data collectors. The training emphasized on the objectives and procedures of the data collection and mode of communication between graders and interviewers. Specifically, the graders were provided with an additional 58 live patients and 100 pictures of different trachoma signs independently. The live patient diagnosis and picture reading were assured by the trainers’ weather they diagnosed correctly or not. Both of the graders were not missed any of the live patients and pictures actual signs. In performing the actual screening, they initially observe the eyelashes and cornea of children to appreciate two of the cicatricial types of trachoma then eversion of the upper lid and inspection of the upper tarsal conjunctiva to identify the active stages using a magnifying binocular lenses (×2.5) and penlight torches as per WHO simplified grading scheme to identify the clinical signs of trachoma: trachomatous inflammation-intense (TI), trachomatous inflammation-follicular (TF), trachomatous conjunctival scar (TS), trachomatous trichiasis (TT), and corneal opacity (CO) [4].
Data analysis and presentation
The data were checked for completeness, coded and entered into Epidemiological Information (Epi -info) version 7 and then transferred to statistical package for social science version 23 for analysis. The data were also checked for normality using Hosmer-Lemeshow-goodness-of-fit. Both bivariable and multivariable analysis was carried out and variables in bivariable analysis with p-value of 0.25 included for multivariable analysis. Potential co-linearity was also considered and tested. Variables with a P-value of less than 0.05 in multivariable analysis were considered as statistically significant. A principal component analysis was performed to categorize the households’ wealth index into lowest or poor, middle, and highest or rich. The result of the analysis expressed in descriptive and inferential statistics. The finding was also presented in the forms of tables, and figures. The main output of the study was presented in considering both types of trachoma (Figure 2).
Data Quality Assurance
The questionnaire was prepared in English and translated to Amharic, and then translated back to English to check its consistency by individuals, who are fluent in both English and Amharic languages. Both of the graders and one of the researchers participated previously in a community-based trachoma survey. The interviewers have also had experience in community-based data collection. The inter-rater variability of eye examination was trying to solve by recruiting certified trachoma graders who participated in two national trachoma surveys. In addition, a pretest on 10% (58) of the questionnaires were done in a village called Kosomender, Meket district. A refreshment training was also delivered for both graders, and interviewers by the principal investigators, and one ophthalmologist for five days. On the third day of the training session, all the teams were gone to the field to check the questioner and did eye examination on the rural preschool children. The result of those 58 children was discussed in the fourth and fifth days of the training.