Conceived and designed the experiments: JDK JN GG BL SB PME. Performed the experiments: JDK JN GG BL PME. Analyzed the data: JDK. Wrote the paper: JDK. Supervised the data analysis, developed
The authors have declared that no competing interests exist.
Blindness due to trachoma is avoidable through Surgery, Antibiotics, Facial hygiene and Environmental improvements (SAFE). Recent surveys have shown trachoma to be a serious cause of blindness in Southern Sudan. We conducted this survey in Ayod County of Jonglei State to estimate the need for intervention activities to eliminate blinding trachoma.
A cross-sectional two-stage cluster random survey was conducted in November 2006. All residents of selected households were clinically assessed for trachoma using the World Health Organization (WHO) simplified grading scheme. A total of 2,335 people from 392 households were examined, of whom 1,107 were over 14 years of age. Prevalence of signs of active trachoma in children 1–9 years of age was: trachomatous inflammation follicular (TF) = 80.1% (95% confidence interval [CI], 73.9–86.3); trachomatous inflammation intense (TI) = 60.7% (95% CI, 54.6–66.8); and TF and/or TI (active trachoma) = 88.3% (95% CI, 83.7–92.9). Prevalence of trachomatous trichiasis (TT) was 14.6% (95% CI, 10.9–18.3) in adults over 14 years of age; 2.9% (95% CI, 0.4–5.3) in children 1–14 years of age; and 8.4% (95% CI, 5.5–11.3) overall. The prevalence of corneal opacity in persons over 14 years of age with TT was 6.4% (95% CI, 4.5–8.3). No statistically significant difference was observed in the prevalence of trachoma signs between genders. Trachoma affected almost all households surveyed: 384/392 (98.0%) had at least one person with active trachoma and 130 (33.2%) had at least one person with trichiasis.
Trachoma is an unnecessary public health problem in Ayod. The high prevalence of active trachoma and trichiasis confirms the severe burden of blinding trachoma found in other post-conflict areas of Southern Sudan. Based on WHO recommended thresholds, all aspects of the SAFE strategy are indicated to eliminate blinding trachoma in Ayod.
Trachoma, a neglected tropical disease, is the leading cause of infectious blindness and is targeted for global elimination by the year 2020. We conducted a survey in Ayod County of Jonglei State, Southern Sudan, to determine whether blinding trachoma was a public health problem and to plan interventions to control this disease. We found the burden of trachoma in Ayod to be one of the most severe ever documented. Not only were adults affected by the advanced manifestations of the disease as is typical for older age groups, but young children were also affected. At least one person with clinical signs of trachoma was found in nearly every household, and 1 in 3 households had a person with severe blinding trachoma. Characteristics previously identified as risk factors were ubiquitous among surveyed households, but we were unable to identify why trachoma is so severe in this location. Surgical interventions are needed urgently to improve vision and prevent irreversible blindness in children and adults. Mass antibiotic distribution may alleviate current infections and transmission of trachoma may be reduced if communities adopt the behavior of face washing and safe disposal of human waste. Increasing access to improved water sources may not only improve hygiene but also reduce the spread of guinea worm and other water-borne diseases.
Trachoma is a disease caused by ocular serovars of the bacterial pathogen
Trachoma is the leading cause of preventable blindness worldwide, endemic in 55 countries and most often found in underdeveloped geographic areas within poor populations.
Many years of civil conflict have impeded development in Southern Sudan resulting in weak infrastructure in most sectors, including health. Additionally, the lack of water and sanitation combine to create an environment conducive not only to trachoma, but also to all the neglected tropical diseases with the exception of Chaga's disease. In particular Southern Sudan has the majority of the current global burden of dracunculiasis (guinea worm disease) and there is a major effort underway to eradicate it.
TF, Prevalence of trachomatous inflammation-follicular in children aged 1–9 years; TF/TI, Prevalence of trachomatous inflammation-follicular and or trachomatous inflammation-intense in children aged 1–9 years; TT, Prevalence of trachomatous trichiasis in persons aged 15 years and above.
This survey was conducted in Ayod County shortly after the rainy season from 31 October to 12 November 2006. Ayod is located in the oil-rich northern area of Jonglei State east of the River Nile. The total population is estimated to be 70,000 based on current guinea worm surveillance data.
We estimated that a total sample size of 1,650 people of all ages and sexes was required to allow for estimation of at least 50% prevalence of TF in children 1–9 years old within a precision of 10% with a design effect of 5 and a prevalence of 2.5% TT in adults over 14 years old within a precision of 1.5% with a design effect of 2, both at a confidence limit of 95%. We assumed that 29% of the total population was aged 1–9 years of age and 50% were older than 14 years. To achieve the desired sample size we selected twenty clusters of twenty households.
A list of all 202 villages in Ayod County, broken down into seven
Training of the survey team was performed over a period of seven days by a clinician experienced in trachoma diagnosis, survey methodology, and conducting surveys in Southern Sudan. The survey team consisted of the following persons: 18 guinea worm field officers from Jonglei State; two local health care workers from Ayod village who had received some training in trichiasis surgery; two disease control coordinators; and one international public health professional. Survey workers received training in examination, interviewing, and sketch mapping and segmentation. All team members had prior experience in conducting household surveys and community interventions. Three days of training was conducted in a classroom and four days were utilized for applied training of trachoma grading, data recording, household sampling and interviewing. After the training, members were split into ten teams and transported by air across the county. Teams stayed in central locations near the airstrips where they were dropped and traversed by foot or boat to complete assigned clusters.
All survey team members received training in the WHO simplified grading system (
Examiner | Inter-observer agreement |
Kappa statistic | |||||
TF | TI | TS | TF | TI | TS | All |
|
1 | 95 | 93 | 98 | 0.9 | 0.7 | 0.9 | 0.9(0.8–1.0) |
2 | 95 | 93 | 95 | 0.9 | 0.7 | 0.8 | 0.9(0.7–1.0) |
3 | 95 | 93 | 95 | 0.9 | 0.7 | 0.8 | 0.8(0.7–1.0) |
4 | 100 | 83 | 90 | 1.0 | 0.4 | 0.7 | 0.8(0.6–0.9) |
5 | 98 | 85 | 85 | 1.0 | 0.5 | 0.6 | 0.7(0.6–0.9) |
6 | 98 | 85 | 85 | 1.0 | 0.5 | 0.6 | 0.7(0.6–0.9) |
7 | 90 | 75 | 90 | 0.8 | 0.4 | 0.7 | 0.7(0.5–0.8) |
8 | 90 | 78 | 88 | 0.8 | 0.3 | 0.6 | 0.6(0.5–0.8) |
9 | 98 | 88 | 68 | 1.0 | 0.6 | 0.3 | 0.6(0.5–0.8) |
10 | 85 | 68 | 90 | 0.7 | 0.3 | 0.7 | 0.6(0.5–0.7) |
Kappa for multiple observers | 0.8(0.7–0.9) | 0.5(0.3–0.5) | 0.6(0.04–0.8) | 0.7(0.6–0.7) |
agreement with our gold standard (WHO standardized slides).
Combined kappa for grading all three signs (TF, TI and TS).
All residents of each household were enumerated regardless of availability for examination. All eligible residents were examined for trachoma using the WHO simplified grading scheme. Before examining eyes of children, observers determined whether a child's face was unclean. An unclean face was defined as the presence of ocular or nasal discharge. Both eyes were then examined for signs of trachoma using an ×2.5 binocular loupe and adequate light. Each eye was examined for TT and CO prior to everting the eyelid to examine the conjunctiva. Analysis was performed based on the findings of the worst eye. Only cases of CO in the presence of trichiasis were considered trachomatous corneal opacity. Any participant diagnosed with TF or TI was offered tetracycline eye ointment. All participants diagnosed with TT were referred to the health center in Ayod for free trichiasis surgery and follow-up. Survey teams made an effort at the end of the day to examine residents not available during the first household visit.
Using structured questionnaires, heads of household were interviewed by survey team members experienced in conducting health interviews. If the head of household was not available, the acting household decision maker was invited to respond to the interview. Prior to the survey, the questionnaire was translated from English to Nuer and piloted in a village not included in the sample to standardize interviews.
The following characteristics have been shown in previous studies to be potential risk factors for trachoma: absence of a household latrine
The data were double entered by two data clerks and compared for consistency using EpiInfo version 3.3.2 (Centers for Disease Control and Prevention [
Based on the prevalence of clinical signs of trachoma and the household characteristics, we calculated the projected targets for the implementation of the full SAFE strategy in Ayod. The population requiring lid surgery was calculated by multiplying the point estimate and confidence limits of TT prevalence in all age groups by the estimated total population. The target for antibiotic distribution and behavior change communication to promote face washing was determined based on the WHO guidelines for mass treatment where district prevalence of TF in 1–9 year-old children exceeds the threshold of 10%. To calculate the need for environmental improvements, the proportion of households without access to an improved water source and latrines was multiplied by the total number of households in the county to obtain targets for water and sanitation. The confidence limits were used to calculate the lower bounds and upper bounds of the projected targets.
The protocol was reviewed and approved by local government authorities and Emory University Internal Review Board (IRB 079-2006). The purpose of the survey was explained and approval was sought by local authorities in Ayod and village chiefs prior to working in any village. Verbal informed consent to participate in trachoma examination and household interview was obtained from heads of households, each individual and parents of minors according to the principles of the declaration of Helsinki. Documentation of verbal consent was initialed and dated by the examiner on data collection forms as approved by the IRB. Personal identifiers were removed from the dataset prior to analysis.
We examined 2,335 participants out of a total of 2,605 residents from 392 households in twenty villages of Ayod County, an 89.6% recruitment rate. All 2,335 participants were examined for TT and CO although lid eversion was not possible on eight participants due to recent trichiasis surgery giving a data set of 2,327 individuals. The mean household size was 7.14 (95% confidence interval [CI], 6.20–8.08) persons per household. Infants less than one year old comprised 3.9% of the examined residents and children 1–9 years of age comprised 36.7%. Persons aged 10 to 14 years made up 10.9% of examined residents and 48.4% were over fourteen years of age. The population distribution of the sample is shown in
The prevalence of clinical signs of trachoma are shown in
Clinical Sign |
Age <1 year | Age 1–9 years | Age 10–14 years | Age >14 years | ||||
TF | 66 | 67.3 (51.9–82.7) | 686 | 80.1 (73.9–86.3) | 177 | 67.3 (54.9–79.7) | 484 | 50.6 (42.3–58.9) |
TI | 48 | 50.1 (34.3–65.9) | 481 | 60.7 (54.6–66.8) | 104 | 44.3 (36.3–52.4) | 295 | 31.0 (23.6–38.4) |
TF and/or TI | 75 | 74.9 (63.5–86.3) | 747 | 88.3 (83.7–92.9) | 190 | 72.6 (61.3–83.8) | 586 | 59.1 (50.7–67.4) |
TS | 6 | 10.2 (0.0–28.5) | 148 | 19.3 (15.7–23.0) | 84 | 31.7 (25.4–37.9) | 630 | 56.5 (50.5–62.4) |
TT | 0 | - | 17 | 2.2 (0.73–3.6) | 10 | 5.2 (0.0–11.3) | 156 | 14.6 (10.9–18.3) |
CO |
0 | - | 7 | 0.73 (0.0–1.7) | 3 | 1.1 (0.0–2.7) | 76 | 6.4 (4.5–8.3) |
CO |
0 | - | 2 | 0.30 (0.0–0.78) | 2 | 1.0 (0.0–2.6) | 54 | 4.7 (3.4–6.0) |
95% confidence limits are in ( ).
Signs may occur in combination, survey participants with multiple trachoma signs appear more than once in the table.
Only participants presenting with CO in the presence of TT were considered to have trachomatous CO.
The prevalence of trichiasis in children 1–14 years of age was 2.9% (95% CI, 0.4–5.3). The prevalence of TT in adults over 14 years of age was 14.6% (95% CI, 10.9–18.3). The design effect for TT in this age group was 2.7. The overall prevalence of TT was 8.4% (95%CI, 5.5–11.3). In the 392 households surveyed, one or more persons had trichiasis in 130 households (33.2%).
There were no statistically significant differences in the odds of clinical signs of trachoma between genders. The odds of trichiasis in females compared to males (all ages) was 1.79 (95% CI, 0.78–4.1), while the odds of active trachoma in girls compared to boys (age 1–9 years) was OR = 0.82 (95% CI, 0.29–2.3).
The signs of active trachoma, TF and TI, were observed most frequently in children 1–9 years of age regardless of gender. Signs of active trachoma decreased with age in both genders. Scarring was observed in young children, and was a more common finding in older age groups. TT was observed in all age groups except in children less than one year old.
Household and individual characteristics in Ayod are displayed in
Characteristic | Percent | 95% CI | |
Unimproved primary source of water | 78.0 | 70.1–85.8 | |
Time to fetch water | 39.8 | 30.2–49.3 | |
Latrine Absent | 95.6 | 92.3–98.9 | |
Solid waste disposal | 79.0 | 63.7–94.3 | |
Cattle ownership | 77.9 | 72.8–83.0 | |
Cattle kept | 53.1 | 45.9–60.3 | |
Radio ownership | 16.1 | 8.1–24.0 | |
Never wash children's faces | 23.2 | 10.3–36.2 | |
Unclean faces in children 1–9 yrs of age | 88.6 | 83.0–94.1 |
The projected SAFE intervention targets are summarized in
Intervention | Estimated Need | Lower bound |
Upper bound |
|
S | 5,080 persons | 3,580 | 7,910 | |
A | 70,000 persons | |||
F | 202 (all villages) | |||
E | 7,800 households | 7,010 | 8,580 | |
9,560 households | 9,230 | 9,890 |
where applicable.
Communities in Ayod are in urgent need of interventions to eliminate trachoma as a public health problem. Active trachoma affected nearly every household in this survey and one in three had at least one person with trichiasis. The prevalence of active trachoma in children 1–9 years of age reported in this survey is, to our knowledge, the highest district-wide estimate ever reported in Southern Sudan. Ngondi
The survey was not designed to capture the reasons as to why trachoma prevalence is so high in Ayod. Potential risk factors for trachoma which are common in Ayod are also seen in other counties within Sudan and in other countries. Because no samples of the organism were collected, it is not possible to compare the virulence of the organism with others found elsewhere. Additionally, it is possible that there is a unique host response because all of the people examined in this survey were of the Nuer ethnic group. The population in Ayod may be marginalized beyond that of populations elsewhere having persevered through many years of civil conflict. Access to essential medications or any health care has been almost nonexistent due to the difficulty in reaching the area. Future trachoma surveys in this area and surrounding areas should explore additional factors that may contribute to the understanding of the severity of trachoma observed.
The limitations of sampling methodology used in previous surveys have been documented.
In past times of conflict, drawing maps was not well accepted because of the potential security threat. This survey was limited only to areas that were considered accessible. Inaccessibility was defined on the basis of security, with localities undergoing disarmament being considered particularly risky for the safety of the survey team. There was no systematic difference in environmental conditions or ethnicity between accessible and inaccessible areas and this should not have affected the findings. Adult men were more likely to be missed at the household visit and may have introduced an over-estimation of clinical findings in adults. However, the demographics of our examined population did not differ statistically from the total registered population.
Solomon et al concluded from a study in Ghana that trained community health volunteers may be used to diagnose active trachoma and distribute antibiotics.
Findings from this survey support anecdotal findings that the village chiefs expressed trachoma to be the most important health problem that troubles their communities. Blinding trachoma is not only severe in the adult population, but also among the children of Ayod. Trichiasis in children 1–14 years of age was nearly 30 times the WHO threshold for an acceptable level of TT cases in adults (2.9% compared to the acceptable threshold of 0.1%).
According to the WHO recommendations, antibiotic distribution is needed in the entire County of Ayod to reduce current infections and community load of
Finally, this survey represents an integrated activity of two neglected tropical disease programs. An extensive work-force of guinea worm surveillance field officers were trained in trachoma diagnosis, survey methodology and most importantly the SAFE strategy. Meetings with local authorities and village chiefs were used to provide education about trachoma control and explain the purpose of the survey, but also to increase awareness of guinea worm surveillance and prevention. The guinea worm eradication program was able to initiate guinea worm surveillance in areas of Ayod where surveillance did not exist and recruit new local field officers to maintain surveillance in those areas. This is one example of how disease control programs are capable of currently practicing integration. In a time of limited resources, neglected tropical disease programs should look for opportunities to integrate with others to increase the value of expenditures for otherwise single disease control activities. This core force of trained community surveillance workers will serve as the backbone of a new integrated disease elimination approach.
We gratefully acknowledge the contribution of the local health workers, community volunteers, guinea worm field officers and The Carter Center staff in conducting field work, supporting the sample selection and coordinating logistics. We acknowledge the contribution of the Government of Southern Sudan and Southern Sudan Relief and Rehabilitation Commission for the facilitation of transport in the field. Also, we thank PACT (