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Understanding the spatial distribution of trichiasis and its association with trachomatous inflammation—follicular

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  • Rebecca Mann Flueckiger
  • Jorge Cano
  • Mariamo Abdala
  • Olga Nelson Amiel
  • Gilbert Baayenda
  • Ana Bakhtiari
  • Wilfrid Batcho
  • Kamal Hashim Bennawi
  • Michael Dejene
  • Balgesa Elkheir Elshafie
  • Aba Ange Elvis
  • Missamou Francois
  • Andre Goepogui
  • Khumbo Kalua
  • Biruck Kebede
  • Genet Kiflu
  • Michael P. Masika
  • Marilia Massangaie
  • Caleb Mpyet
  • Jean Ndjemba
  • Jeremiah M. Ngondi
  • Nicholas Olobio
  • Patrick Turyaguma
  • Rebecca Willis
  • Souleymane Yeo
  • Anthony W. Solomon
  • Rachel L. Pullan
Article number364
<mark>Journal publication date</mark>30/04/2019
<mark>Journal</mark>BMC Infectious Diseases
Number of pages16
Publication StatusPublished
<mark>Original language</mark>English


Whilst previous work has identified clustering of the active trachoma sign “trachomatous inflammation—follicular” (TF), there is limited understanding of the spatial structure of trachomatous trichiasis (TT), the rarer, end-stage, blinding form of disease. Here we use community-level TF prevalence, information on access to water and sanitation, and large-scale environmental and socio-economic indicators to model the spatial variation in community-level TT prevalence in Benin, Cote d’Ivoire, DRC, Guinea, Ethiopia, Malawi, Mozambique, Nigeria, Sudan and Uganda.

We fit binomial mixed models, with community-level random effects, separately for each country. In countries where spatial correlation was detected through a semi-variogram diagnostic check we then fitted a geostatistical model to the TT prevalence data including TF prevalence as an explanatory variable.

The estimated regression relationship between community-level TF and TT was significant in eight countries. We estimate that a 10% increase in community-level TF prevalence leads to an increase in the odds for TT ranging from 20 to 86% when accounting for additional covariates.

We find evidence of an association between TF and TT in some parts of Africa. However, our results also suggest the presence of additional, country-specific, spatial risk factors which modulate the variation in TT risk.