Australian Trachoma Surveillance Report 2013

Data analysis

Page last updated: 2015

For the purpose of this report, a community is defined as a specific location where people reside and where there is at least one school. Community coverage is defined as the number of at-risk communities screened for trachoma as a proportion of those that were identified to possibly have trachoma. Individual screening coverage is the proportion of children in the target age group in a region that was actually screened.

In 2013, population data for trachoma screening coverage were provided by each jurisdiction. The population for communities in years 2007 to 2011 was derived from projected data from the 2006 Australian census using Australian Bureau of Statistics (ABS) standard estimates of population increase (1.6%, 1.8% and 2.1% in the NT, WA and SA, respectively). Population estimates based on ABS census data do not account for population movements within communities, regions and jurisdictions. Prevalence of active trachoma was calculated using the number of children screened as the denominator.

Trachoma data were analysed in the age groups 0-4, 5-9 and 10-14 years. Comparisons over time were limited to the 5-9-year age group, which is the target age group for the trachoma screening programs in all regions. Data from 2006 were excluded from assessment of time trends as collection methods in this first year differed from those subsequently adopted.

Projected data for trachoma prevalence

In 2013 the NT delivered trachoma control activities according to the newly revised 2014 CDNA National guidelines for the public health management of trachoma in Australia (reference 2). Under these guidelines, a community would be excluded from screening activities for up to 3 years if high screening coverage had been achieved in the recent past and either prevalence of trachoma was less than 5%, or it was 5% or more without obvious clustering. Exclusion of these communities from screening activities leads to less reliable trachoma surveillance data during the interim period for the total level and trend in trachoma in which the community is located. For reporting purposes, the NTSRU has carried the most recent prevalence data forward in those communities that did not screen in the 2013 calendar year as a direct program decision, providing what is believed to be a conservative upper-bound on average levels of trachoma. This principle will apply to all tables and figures relating to trachoma prevalence data. This method of projecting data was approved by the Trachoma Surveillance and Control Reference Group on 26 November 2013.