2025/01/01 by O S Abdurahman · 1 voice
Immunology and Microbiology · Medicine · #Cervical Cancer and HPV Research #Reproductive tract infections research #Syphilis Diagnosis and Treatment
paper · doi:10.17037/pubs.04678098
openalex publication_date 2025/01/01 · openalex created_date 2026/01/21 · openalex updated_date 2026/07/01
This thesis investigates the transmission and the natural history of ocular Chlamydia trachomatis (Ct) infection, using molecular tools, including mRNA based reverse transcription. The study was conducted in Ethiopia, where the prevalence of trachoma remains high despite many years of the implementation of SAFE strategy- an integrated approach to trachoma control consisting of Surgery for trichiasis (S), Antibiotics to treat infection(A), Facial cleanliness(F), and Environmental improvement(E). The thesis begins with an investigation into the risk factors for trachoma transmission through a cross-sectional survey of 247 households in a trachoma-endemic community in Oromia Region. This community exhibited a high prevalence of active trachoma - trachomatous inflammation–follicular (TF) and/or trachomatous inflammation–intense (TI). Our findings revealed that younger children, the presence of flies on children's faces during visits, and ocular discharge were significantly associated with active trachoma. Additionally, preschool children who had their faces washed more than once a day had lower odds of contracting the disease. A unique aspect of this study was its analysis of asset-based socioeconomic status, which demonstrated a clear association between trachoma prevalence and poverty—an association previously established for the later stages of trachoma but not well-documented for early-stage disease. To further investigate the natural history and transmission dynamics of Ct, we recruited 298 individuals from 68 adjacent households for a year-long, biweekly longitudinal study. However, shortly after initiating the study, COVID-19 was detected in Ethiopia, prompting a government-mandated halt to all community-level fieldwork. Six months later, we resumed data collection. For analytical purposes, the first two timepoints prior to the fieldwork pause were used as baseline data and proof-of-concept, during which we collected eye, hand, and face swabs. From these baseline samples, Ct DNA was detected in 16 of 133 (12.0%) eye swabs, with 12 of those 16 (75.0%) also testing positive for Ct mRNA, indicating viable infection. Among face swabs, 14 of 105 (13.5%) contained Ct DNA, of which 6 of 14 (42.9%) were Ct mRNA positive. Similarly, 11 of 105 (10.5%) hand swabs tested positive for Ct DNA, with 4 of 11 (36.4%) also Ct mRNA positive. Among individuals with mild disease (F1 and 4 or P1/P2), 85% had developed to severe disease (F2/F3 and or P3) from the first timepoint to second timepoint, and no participants showed clearance of infection within two weeks. Following the resumption of the study, we analysed data from 22 time points. Throughout the study period, the prevalence of TF, TI, and detectable Ct DNA remained consistently high. Notably, 83% of all Ct DNA-positive cases also tested positive for Ct mRNA, confirming likely viable infection, while non-viable Ct DNA was consistently of low bacterial load. All individuals with detectable Ct mRNA were children aged 2–9 years. The duration of infection episodes for Ct DNA and Ct mRNA was 2-28 weeks and 2-24 weeks respectively, whereas TF and TI lasted for the duration of 2-26 weeks and 2-14 weeks, respectively. Infections exhibited strong spatial clustering within and between households, particularly among children aged 2–5 years. By overlaying Ct infections with active disease progression over time, we observed a clear pattern: initial inoculation was followed by epithelial infection, disease onset, and eventual infection clearance— though clinical signs of the disease often persisted beyond infection resolution. Among individuals who reported receiving treatment, 85.7% of Ct mRNA-positive cases showed successful clearance. This thesis provides new insights into the dynamics of Ct transmission, emphasizing the role of young children as key reservoirs of infection and highlighting the importance of early intervention, hygiene practices, and socioeconomic considerations in trachoma control efforts.