National Trachoma Prevalence Survey

Trachoma is the leading infectious cause of blindness worldwide. Although the disease has largely disappeared from Europe and the Americas, predating the advent of antibiotics, trachoma appears to be hyperendemic in many of the poorest and most remote areas.

Worldwide, an estimated 84 million people are affected by Trachoma, of whom about 8 million are visually impaired or blind.

Trachoma is caused by Chlamydia Trachomatis - a micro organism which spreads through contact with eye discharge from the infected person and through transmission by eye-seeking flies.

After years of repeated active infection, the inside of the eyelid may be scarred so severely that the eyelid turns inward and the lashes rub on the eyeball.

This stage of active infection throughout childhood and young adulthood is called Trachomatous Follicular Inflammation (TF) or Intense Trachomatous Inflammation (TI).

If active infection is untreated, the constant rubbing on the eyeball leads to scarring of the cornea (the clear window of the eye), forming irreversible corneal opacities that leads to blindness later in life. The blinding stage of the disease is referred to as Trachomatous Trichiasis (TT) or Corneal Opacity (CO).

Established risk factors for trachoma include lack of adequate water supply, flies, cattle ownership and poor hygiene conditions. Trachoma is commonly passed among family members and community members in households that are in close proximity. It often strikes the most vulnerable members of communities - women and children.

A three-day pre-survey workshop was conducted to standardise examiners and field-test the survey data collection tools. A total of six survey teams (each comprised of two ophthalmic officers, an ophthalmic nurse, two clinical assistants and one driver) were established with two teams covering one zoba.

The survey took place in three representative zobas: Debub (Central Highland), Gash Barka (Western Lowlands) and Northern Red Sea (Coastal Plains). Villages that were included in the survey were randomly selected within each zoba.

Households were randomly selected in each village and eligible occupants were enumerated and examined. Consent was sought from the head of the household prior to the examination.

More than 1800 households were included. The overall response rate to participate in the study was high (85%). Of the 6430 participants, 2918 (45%) were children (1 to 9 years) and 3514 (55%) were adults aged 15 years and over.

The prevalence of trachoma (TF) in younger children (1 to 5 years) was 9% and 7% in older children (6 to 9 years). The prevalence in children varied substantially depending on the geographical region, from 15% in Debub to 2% in Gash Barka. In one Debub sub-district, as many as 69% of children had trachoma.

Trachoma (TT) was less prevalent in younger adults (0.2% if aged 15 to 29 years) compared to older adults (0.7% if aged 30 to 44 years; 4.4% if over 44 years). The prevalence ranged geographically from 2.2% in Debub to 1.1% in the Northern Red Sea Zoba.

Only 15% of households own any kind of pit toilet, the majority without cover. More than half of all households accommodate an animal pen, most of which are within 1 to 5 metres from the living quarters.

Garbage and human faeces were observed within 15 metres of the households in 60% and 47%, respectively. In about 90% of the households flies were observed on the face of the children. Most of the participants had no schooling; from 57% in Debub to 74% in the Northern Sea Zoba.

The prevalence of trachoma (TF) in children was related to having a dirty face and the lack of water supply throughout the year. Trachoma (TT) in adults was associated with lack of schooling.

Trachoma was more prevalent in children and adults in households with an animal pen close to dwelling quarters. If the pen was further away from the living quarter, the prevalence of trachoma was reduced. The disease was more than twice as common in children if human faeces were present within close range to households.

Both active and blinding trachoma were found in the regions assessed. Active trachoma appeared to be a public health problem mainly in the Debub Zoba (15%). This is lower compared to findings in South Western Ethiopia (32%) or Mali (35%). As expected, a higher trachoma prevalence was related to poor sanitation. 

Although other countries in the region have conducted trachoma prevalence studies, the burden of trachoma in Eritrea has not been assessed previously.

Knowledge of the prevalence of active and blinding trachoma across Eritrea is important in planning, implementing and evaluating for a successful National Trachoma Control Program.

Based on the World Health Organization adopted 'SAFE' strategy, this multi-faceted approach includes lid surgery (S), antibiotics to treat the community pool of infection (A), facial cleanliness (F) and environmental changes (E).

In-line with international guidelines, mass distribution of antibiotics (Zithromax) should be considered in areas with a prevalence of over 10%. The survey will support the development of a plan of action to implement the SAFE strategy and to target specific areas with a higher prevalence rate.

Survey outcomes have also underlined the importance of reducing new infections through the improvement of hygiene and environmental sanitation.

For further information about this survey or The Foundation's work in Australia please contact: 

Dr Andreas Mueller
Project Coordinator - International Programs
The Fred Hollows Foundation in Australia
Phone: +61 2 8741 1917
Email: amueller@hollows.org