Trachoma Epidemiology in Ceará, Brazil

We conducted an ecological study based on epidemiological data on trachoma in the state of Ceará (Figure 1), reported in the Information System on Notifiable Diseases (SINAN) by the Secretary of Health of the State of Ceará. This database contains the records of surveys conducted in municipalities in the state of Ceará. Information was collected from individuals who were examined and diagnosed with trachoma upon external eye examinations. Data from 2007 to 2021 were used in this study. Beginning in 2007, the results of trachoma investigations were made available in SINAN by the Secretary of Health of the state of Ceará.
FIGURE 1:During the study period (2007-2021), school and household surveys were developed concomitantly. Between 2011 and 2013, household surveys predominated, with a proposed sampling of 80% of households. School surveys continued in the period 2013-2017 as part of the Ministry of Health’s “National Campaign on Leprosy, Worms, Trachoma, and Schistosomiasis”. During this period, external eye examinations were conducted among public school students aged 5-14. From 2017, following the "Panel of Strategic Health Surveillance Indicators of the State of Ceará”, the proposed sample was 50% or more of students aged 1-9 in the public elementary school network of the municipalities considered a priority that was part of each health region. The contents of schoolchildren with trachoma were examined through household surveys.
Our analysis was based on calculating absolute and relative frequencies using the percentage of positivity. To this end, we counted the number of positive cases of trachoma, divided it by the total number of individuals examined, and multiplied this by 100. The operational parameters proposed as a reference by the Brazilian Ministry of Health consider variations in endemicity levels, with values <5.0%, 5.0-9.9%, and ≥10.0%.
Demographic and clinic-epidemiological patterns were characterized according to the percentage of positivity for trachoma and represented based on the levels of endemicity in the period 2007-2021, according to the following variables: health regions of the state of Ceará (Figure 1), using the administrative management model adopted by the Health Department of the state of Ceará, with subdivisions and respective number of municipalities (Litoral Leste/Jaguaribe [20], Cariri [45], Sertão Central [20], Norte [55], and Fortaleza [44]); sex (male and female); age group (0-4, 5-9, 10-14, and ≥15 years); area of residence (urban, peri-urban or rural); clinical forms, according to the case definition for the disease based on the active forms (trachomatous inflammation follicular [TF], presence of ≥ 5 follicles > 0.5 mm in the upper tarsal conjunctiva of the eye; trachomatous inflammation intense [TI], inflammatory thickening of the upper tarsal conjunctiva, not allowing visualization of > 50% of the deep tarsal vessels); and sequelae forms (trachomatous scarring [TS], presence of scarring of the upper tarsal conjunctiva; trachomatous trichiasis [TT], presence of at least one of the lashes rubbing the eyeball or evidence of recent epilation of lashes on the upper eyelid; and corneal opacity [CO], opacity obscuring the pupillary margin)⁴.
The organization and management of the database were performed using the statistical program Stata 11.2 (Stata Statistical Software, StataCorp LP, College Station, TX, USA) through the construction of tables and graphs.
The temporal patterns of positivity for the disease were analyzed considering the variation in endemicity levels in the health regions of the State of Ceará for the entire period of 2007-2021. The data were exported and joined to the shapefiles of the municipalities of the state of Ceará, according to the standards of the Brazilian Institute of Geography and Statistics, using the software QGIS version 2.18.6 (licensed under the General Public License [GNU], available at https://qgis.org/pt_BR/site/. We constructed thematic maps by verifying the spatial patterns of endemicity in the pre- coronavirus disease (COVID-19) pandemic period (2007-2010, 2011-2014, 2015-2019) and during the COVID-19 pandemic (2020-2021).
This study was approved by the Ethics Committee of the Hospital São José de Doenças Infecciosas (HSJ) of the State of Ceará (opinion number 5.132.182).