Community-level trachoma ecological associations and the use of geospatial analysis methods: A systematic review

Abstract

Background Trachoma is targeted for global elimination as a public health problem by 2030. Understanding individual, household, or community-associated factors that may lead to continued transmission or risk of recrudescence in areas where elimination has previously been achieved, is essential in reaching and maintaining trachoma elimination. We aimed to identify climatic, demographic, environmental, infrastructural, and socioeconomic factors associated in the literature with trachoma at community-level and assess the strength of their association with trachoma. Because of the potential power of geospatial analysis to delineate the variables most strongly associated with differences in trachoma prevalence, we then looked in detail at geospatial analysis methods used in previous trachoma studies. Methods We conducted a systematic literature review using five databases: Medline, Embase, Global Health, Dissertations & Theses Global, and Web of Science, including publications from January 1950 to January 2021. The review protocol was prospectively registered with PROSPERO (CRD42020191718). Results Of 35 eligible studies, 29 included 59 different trachoma-associated factors, with eight studies also including spatial analysis methods. Six studies included spatial analysis methods only. Higher trachomatous inflammation—follicular (TF) prevalence was associated with areas that: had lower mean annual precipitation, lower mean annual temperatures, and lower altitudes; were rural, were less accessible, had fewer medical services, had fewer schools; and had lower access to water and sanitation. Higher trachomatous trichiasis (TT) prevalence was associated with higher aridity index and increased distance to stable nightlights. Of the 14 studies that included spatial methods, 11 used exploratory spatial data analysis methods, three used interpolation methods, and seven used spatial modelling methods. Conclusion Researchers and decision-makers should consider the inclusion and potential influence of trachoma-associated factors as part of both research activities and programmatic priorities. The use of geospatial methods in trachoma studies remains limited but offers the potential to define disease hotspots and areas of potential recrudescence to inform local, national, and global programmatic needs.

Trachoma and the Importance of Sexual Infective Route in Developed Countries. Comment on Gallenga et al. Why the SAFE—S Strategy for Trachoma? Are Musca sorbens or Scatophaga stercoraria Really the Culprit?—A Brief Historical Review from an Italian Point of View. Pathogens 2023, 12, 1419

“…The incidence of visual impairment due to Trachoma is lower in European and Latin American countries in comparison to African countries [2,3], due to Trachoma's association with rural and lower-income areas [1], as has been clearly pointed out in the discussed review article. As stated by the authors, Trachoma's global elimination has been proposed for 2030 [3].…”

“…The incidence of visual impairment due to Trachoma is lower in European and Latin American countries in comparison to African countries [2,3], due to Trachoma's association with rural and lower-income areas [1], as has been clearly pointed out in the discussed review article. As stated by the authors, Trachoma's global elimination has been proposed for 2030 [3]. The appearance of "fly killers" has induced a decrease in the total population of eye-seeking flies, not only in highest-income countries but also in rural and lower-income areas [4].…”

The Prevalence of Trachomatous Trichiasis in People Aged 15 Years and Over in Six Evaluation Units of Gaoual, Labé, Dalaba and Beyla Districts, Guinea

“…Geospatial analysis may be a useful approach for providing more precise TT prevalence estimates either through more efficient survey design or generating estimates using existing survey data, if appropriate. 39 …”

Using model-based geostatistics for assessing the elimination of trachoma

“…We show here that MBG can be effectively used in different epidemiological settings, both with very low trachoma prevalence, such as Brazil and Malawi, and relatively high prevalence, such as Niger. Future extensions of the proposed MBG framework will aim to incorporate spatially referenced covariate effects to account for well-established factors associated with trachoma, such as temperature, elevation, and precipitation [54]. However, whilst it is generally good practice to use covariates to aid spatial predictions of prevalence, it can be problematic in the context of low prevalence.…”