Trachoma: global magnitude of a preventable cause of blindness.
OBJECTIVE
Trachoma is the leading cause of infectious blindness worldwide. It is known to be highly correlated with poverty, limited access to healthcare services and water. In 2003, the WHO estimated that 84 million people were suffering from active trachoma, and 7.6 million were severely visually impaired or blind as a result of trachoma: this study provides an updated estimate of the global prevalence of trachoma based on the most recent information available.


METHODS
A literature search of recent published and unpublished surveys in the 57 endemic countries was carried out: the result of surveys that used the WHO trachoma grading system and additional information from regional and country experts served as a basis to determine the prevalence of trachoma in each country.


RESULTS
Population-based surveys provided recent information for 42 out of 57 endemic countries. 40.6 million people are estimated to be suffering from active trachoma, and 8.2 million are estimated to have trichiasis.


CONCLUSIONS
The current estimate of prevalence of trachoma is lower than the previous WHO estimates: this can be explained by the success in implementing control strategy, by more accurate data, as well as by socio-economic development in endemic countries.
Mariotti
S P
SP
Chronic Disease and Health Promotion Department, Prevention of Blindness and Deafness, World Health Organization, Geneva, Switzerland. mariottis@who.int
Pascolini
D
D
Rose-Nussbaumer
J
J
D001766:Blindness / Q000382:microbiology*; D019353:Endemic Diseases / Q000706:statistics & numerical data; D014943:Global Health; D006801:Humans; D015995:Prevalence; D014141:Trachoma / Q000150:complications / Q000453:epidemiology*