Prevalence of Trachoma in Alto Amazonas, Loreto Department, Perú

Abstract

Purpose : The Pan American Health Organization (PAHO) has identified trachoma as a potential public health problem in Perú. We performed a cross-sectional study to determine the prevalence of trachoma in Alto Amazonas, Perú.

Methods : We selected 22 communities via probability-proportional-to-size sampling after excluding urban areas. In a random selection of approximately 30 households per community, all children aged 1-9 were examined for trachomatous inflammation—follicular (TF) and trachomatous inflammation—intense (TI), and individuals aged 15+ years were evaluated for trachomatous trichiasis (TT), i.e., upper lid trichiasis, using the World Health Organization’s (WHO) 2018 amended trachoma grading system. Each child’s right conjunctiva was swabbed and tested for Chlamydia trachomatis DNA.

The community level prevalence of TF, TI, and ocular C. trachomatis was adjusted for age in one-year bands and TT prevalence was adjusted using 5-year age bands. The overall prevalence of each outcome was the mean of the age-adjusted community level prevalence. 95% confidence intervals were calculated using bootstrapping methods with resampling at the community level (10,000 replications).

Results : One community refused. The location and number examined in the other 21 communities are shown in Figure 1. 617 selected households were enumerated, with 873 children aged 1-9 and 1313 adults 15+ eligible for examination of whom 778 (89.1%) and 1003 (76.4%) were examined, respectively. On average, the prevalence of TF among 1–9-year-olds was 32.6% and the prevalence of ocular C. trachomatis was 0.8% (Table 1). The prevalence of TT among individuals ≥15 years was 0.06%.

Conclusions : The overall prevalence of TF was above the WHO 5% threshold for active trachoma as being a public health problem. Consequently, the area is eligible for the implementation of trachoma elimination interventions, including annual mass administration of antibiotics for at least 5 years. The discrepancy between high TF and low ocular C. trachomatis prevalence requires further investigation.

This is a 2021 ARVO Annual Meeting abstract.

 

Figure 1. The upper-left insert shows the location of the study area in Perú. The main panel demonstrates the study area with the communities visited plotted as black dots, whose size is proportional to the number of individuals examined in each community.

 

Table 1. Demographic information for the 1–9 and 15+ years age groups, prevalence estimates and their bootstrapped 95% confidence intervals.