© Rajan Shrestha

Trachoma is a painful, blinding disease that over 100 million people worldwide are at risk from. The disease is caused by the bacterium Chlamydia trachomatis (Ct). Repeated infections with the bacteria eventually cause the eyelashes to turn inwards, scratching the cornea and causing irreversible blindness.

Ethiopia has the highest proportion of people at risk, with over 61 million people living in endemic areas.

It is theorised that children are the main reservoir for the bacteria, transmitting it between people via their face and hands.

A new study by ICEH has assessed the presence of the bacteria in children in one area of Ethiopia, providing more evidence for routes of transmission and potential future solutions.

In the research, two hundred and ninety-eight people were enrolled from 68 neighbouring households in the Shashemene area of Oromia, Ethiopia, and everyone above 2 years of age examined for signs of trachoma. Swabs were also collected from the participant’s eyes, hands and faces to assess the presence of Ct.

The researchers found that out of 133 children:

• 20% had trachomatous inflammation-follicular (TF)
• 6% had trachomatous inflammation-intense (TI)
• Out of the swabs:
  • 12% of eye swabs ,14% of face swabs, and 11% of hand swabs showed Ct
  • 86% of those with Ct on their faces had it in their eyes, as did 82% of those with Ct on their hands

The Ct was also tested for viability using mRNA reverse transcription PCR. Viability testing assesses whether the bacteria is living, an indicator of its potential to spread. Viable Ct was detected in 75% ocular, 43% face, and 36% of hand swab samples. All viable Ct detected on faces and hands was identified from individuals with viable ocular infections.

The caregivers of the children also showed the presence of Ct, with 20% of the parents of the children who had Ct on their hands also having it on their hands, and 14% of the parents of those with Ct on their faces also having it on their faces.

Two children who didn’t have Ct in their eyes but had it on their hands were found to have it in their eyes two weeks later.

The findings provide evidence of how the bacteria that leads to trachoma exists in a high-risk setting. This type of data can be useful when developing solutions to interrupt transmission of the bacteria and efforts to eliminate the disease.

The authors note that future research could map the transmission of viable Ct in communities before and after interventions to assess the effectiveness of reducing the bacteria.

Publication

Abdurahman OS, Bekele G, Butcher R, Deressa G, Mumme A, Mohammed M, et al. Distribution and viability of ocular and non-ocular Chlamydia trachomatis in households in a trachoma-endemic community in Oromia, Ethiopia. PLoS Neglected Tropical Diseases. January 2025. https://doi.org/10.1371/journal.pntd.0012759