Targeting Trachoma Control through Risk Mapping: The Example of Southern Sudan

Trachoma, caused by the bacterium Chlamydia trachomatis, is the leading cause of preventable blindness worldwide and a major cause of blindness in Southern Sudan. However, the trachoma distribution in Southern Sudan has only been partially established and many communities in need of intervention have not been identified or targeted. Incomplete mapping and intervention coverage is largely attributable to trachoma resources being scarce and not always deployed most efficiently. The present study aimed at improving programme efficiency by developing maps to help target the available resources for trachoma surveys and interventions to areas where these are most needed. Data on active trachoma prevalence, collected during baseline surveys between 2001 and 2009, were incorporated into Bayesian geostatistical models to develop a national trachoma risk map. The model predicted the west of the country to be largely at no or very low trachoma risk, while most of the high-risk areas are located in the centre, north, and south-east. Risk mapping has allowed Southern Sudan's trachoma control programme to identify areas where collection of additional data would be most useful. As a direct result, baseline data were collected in March 2010 for the whole of Unity State, with antibiotic mass drug administration being scaled up from June 2010 onwards

The Burden of Trachoma in Ayod County of Southern Sudan

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

Reliability among 10 survey examiners using the WHO standardized set of slides.

*<p>agreement with our gold standard (WHO standardized slides).</p>**<p>Combined kappa for grading all three signs (TF, TI and TS).</p

Household and Individual Characteristics.

<p>Household and Individual Characteristics.</p

Age-specific Prevalence of Cicatricial Trachoma (TS and TT), by sex.

<p>Age-specific Prevalence of Cicatricial Trachoma (TS and TT), by sex.</p

Prevalence Estimates of the Clinical Signs of Trachoma by Age group, Ayod County, Southern Sudan 2006.

<p>95% confidence limits are in ( ).</p>†<p>Signs may occur in combination, survey participants with multiple trachoma signs appear more than once in the table.</p>*<p>Only participants presenting with CO in the presence of TT were considered to have trachomatous CO.</p

Summary of SAFE Intervention targets.

*<p>where applicable.</p

The WHO simplified grading scheme for assessment of Trachoma.

<p>The WHO simplified grading scheme for assessment of Trachoma.</p

Age-specific Prevalence of Active Trachoma (TF and TI), by sex.

<p>Age-specific Prevalence of Active Trachoma (TF and TI), by sex.</p