The Natural History of Trachoma Infection and Disease in a Gambian Cohort with Frequent Follow-Up

Abstract

BackgroundThe natural history of ocular Chlamydia trachomatis infections in endemic communities has not been well characterised and is an important determinant of the effectiveness of different mass treatment strategies to prevent blindness due to trachoma.Methodology/Principal FindingsA multistate hidden Markov model was fitted to data on infection and active disease from 256 untreated villagers in The Gambia who were examined every 2 weeks over a 6-month period. Parameters defining the natural history of trachoma were estimated, and associations between these parameters, demographic and baseline immune measurements examined. The median incubation period following infection was estimated at 17 days (95% confidence interval: 11–28). Disease persisted for longer than infection (median 21 (15–32) weeks) versus 17 (12–24) weeks), with an estimated median duration of post-infection inflammation of 5 (3–8) weeks. The duration of active disease showed a significant decline with age even after accounting for lower rates of re-infection and disease at older ages (p = 0.004). Measurements of levels of baseline IgA to epitopes in the major outer membrane protein of Chlamydia trachomatis were not significantly correlated with protection or more rapid clearance of infection.ConclusionsThe average duration of infection with Chlamydia trachomatis especially at younger ages is long. This contributes to the persistence and gradual return of trachoma after community-wide treatment with antibiotics.

The Effect of Multiple Rounds of Mass Drug Administration on the Association between Ocular Chlamydia trachomatis Infection and Follicular Trachoma in Preschool-Aged Children

“…The disease disproportionately affects individuals living in rural and resource-poor settings, and children are the primary carriers of ocular C. trachomatis infection and active disease [3]. We and others have previously shown that clinical disease persists longer than infection in children such that in any prevalence survey, a significant proportion of children will have active trachoma without demonstrable signs of C. trachomatis infection [4], [5], [6].…”

Evidencia clínica de tracoma en indígenas colombianos del departamento de Vaupés

“…La enfermedad comienza en los niños, principalmente en aquéllos entre 2 y 5 años de edad, en los cuales tiene mayor duración (22)(23)(24), como lo vemos en los casos demostrados, 61% de los cuales eran menores de 15 años. Ellos son la fuente principal de la bacteria; la transmiten a los otros niños y a sus madres (25), principalmente, a través del contacto estrecho, como compartir camas y juegos, que permiten entrar en contacto con las secreciones oculares, o por el intercambio de utensilios contaminados o fómites, como las toallas (1-4,17,22-24).…”

Trachoma

“…Previously, scarring complications were often ascribed to adaptive immune responses, since adults have consistently lower bacterial loads than those of children and experience short duration of infection, presumably as a result of acquired immune responses. [7,18,19]…”