Trachoma is a contagious infection of the eye by specific strains of the bacteria Chlamydia trachomatis (C.trachomatis). Active trachoma, which occurs most frequently in children, is clinically diagnosed by signs of follicles and papillae on the conjunctival epithelium of the upper lid14. These occur as a result of the inflammatory response following infection with C.trachomatis. Repeated rounds of infection may result in scarring leading to distortion of the eyelids and upper lid entropion (in-turning of the eyelids). As a result of this in-turning, eyelashes rub on the globe, a condition known as trichiasis. Trichiasis can lead to corneal opacity and eventually blindness15.

The main source of trachoma infection is human cases of active trachoma. The prevalence of active trachoma is highest among pre-school aged children, and infections in children persist longer than those in adults, suggesting that young children form a reservoir for infection16. Animal reservoirs of C.trachomatis have not been found17. Routes of transmission include18:

  • direct eye-to-eye spread (e.g. while playing or sharing a bed);
  • conveyance on fingers;
  • indirect spread on fomites (e.g. shared towels); and
  • eye-seeking flies.
The relative importance of these routes is likely to vary with time, place and cultural norms; it is difficult to establish the relative importance of each route19. Trachoma prevalence varies greatly between communities within a geographical area. Within a community, trachoma is strongly clustered by households; within households it is clustered by sleeping rooms. This suggests that sustainable transmission depends on close, prolonged contact. Trachoma occurs more commonly in dry, dusty conditions and is associated with sub-optimal living conditions such as overcrowding, reduced availability and use of water (for washing hands, faces and clothing), inadequate waste disposal and high numbers of flies20.

Thylefors B, Dawson CR, Jones BR, West SK, Taylor HR (1987). A simple system for the assessment of trachoma and its complications. Bull World Health Organ; 65:477-83.
Polack S, Brooker S, Kuper H, Mariotti S, Mabey D and Foster A (2005). Mapping the global distribution of trachoma, Bulletin of the World Health Organization; 80 (12)
West SK, Munoz B, Turner VM, Mmbaga BBO and Taylor HR (1991). The epidemiology of trachoma in central Tanzania. International Journal of Epidemiology 20:1088–1092.
Emerson PM, Cairncross S, Bailey RL and Mabey DCW (2000). Review of the evidence base for the ‘F’ and ‘E’ components of the SAFE strategy for trachoma control. Tropical Medicine and International Health 5:515–527.
Department of Health and Ageing (2006). Guidelines for the public health management of trachoma in Australia, Communicable Disease Network Australia
Emerson PM, Cairncross S, Bailey RL and Mabey DCW (2000). Review of the evidence base for the ‘F’ and ‘E’ components of the SAFE strategy for trachoma control. Tropical Medicine and International Health, 5:515–527.
Department of Health and Ageing (2006). Guidelines for the public health management of trachoma in Australia, Communicable Disease Network Australia

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