Detecting extra-ocular Chlamydia trachomatis in a trachoma-endemic community in Ethiopia: Identifying potential routes of transmission

04 Mar 2020
Anna Last, Bart Versteeg, Oumer Shafi Abdurahman, Ailie Robinson, Gebeyehu Dumessa, Muluadam Abraham Aga, Gemechu Shumi Bejiga, Nebiyu Negussu, Katie Greenland, Alexandra Czerniewska, Nicholas Thomson, Sandy Cairncross, Virginia Sarah, David Macleod, Anthony W. Solomon, James Logan, Matthew J. Burton

Background

Trachoma elimination efforts are hampered by limited understanding of Chlamydia trachomatis (Ct) transmission routes. Here we aimed to detect Ct DNA at non-ocular sites and on eye-seeking flies.

Methods

A population-based household survey was conducted in Oromia Region, Ethiopia. Ocular and non-ocular (faces, hands, clothing, water containers and sleeping surfaces) swabs were collected from all individuals. Flies were caught from faces of children. Flies, ocular swabs and non-ocular swabs were tested for Ct by quantitative PCR.

Results

In total, 1220 individuals in 247 households were assessed. Active trachoma (trachomatous inflammation—follicular) and ocular Ct were detected in 10% and 2% of all-ages, and 21% and 3% of 1–9-year-olds, respectively. Ct was detected in 12% (95% CI:8–15%) of tested non-ocular swabs from ocular-positive households, but in none of the non-ocular swabs from ocular-negative households. Ct was detected on 24% (95% CI:18–32%) of flies from ocular-positive households and 3% (95% CI:1–6%) of flies from ocular-negative households.

Conclusion

Ct DNA was detected on hands, faces and clothing of individuals living in ocular-positive households suggesting that this might be a route of transmission within Ct infected households. In addition, we detected Ct on flies from ocular-positive households and occasionally in ocular-negative households suggesting that flies might be a vector for transmission within and between Ct infected and uninfected households. These potential transmission routes may need to be simultaneously addressed to suppress transmission.